# OpenSearch Helm Chart

This Helm chart installs [OpenSearch](https://github.com/opensearch-project/OpenSearch) with configurable TLS, RBAC and much more configurations. This chart caters a number of different use cases and setups.

- [OpenSearch Helm Chart](#opensearch-helm-chart)
- [Requirements](#requirements)
- [Installing](#installing)
- [Uninstalling](#uninstalling)
- [Configuration](#configuration)

## Requirements

- Kubernetes >= 1.14
- Helm >= 2.17.0
- We recommend you to have 8 GiB of memory available for this deployment, or at least 4 GiB for the minimum requirement. Else, the deployment is expected to fail.

## Installing

Once you've added this Helm repository as per the repository-level [README](../../README.md#installing) then you can install the chart as follows:

```shell
helm install my-release opensearch/opensearch
```

The command deploys OpenSearch with its associated components (data statefulsets, masters, clients) on the Kubernetes cluster in the default configuration.

**NOTE:** If using Helm 2 then you'll need to add the [`--name`](https://v2.helm.sh/docs/helm/#options-21) command line argument. If unspecified, Helm 2 will autogenerate a name for you.

## Uninstalling

To delete/uninstall the chart with the release name `my-release`:

```shell
helm uninstall my-release
```

## Configuration

| Parameter                                 | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | Default                                                                                                         |
| :---------------------------------------- | :  | :-------------------------------------------------------------------------------------------------------------- |
| `antiAffinityTopologyKey`                 | The [anti-affinity][] topology key. By default this will prevent multiple Opensearch nodes from running on the same Kubernetes node                                                                                                                                                                                                                                                                                                                                                                                                | `kubernetes.io/hostname`                                                                                        |
| `antiAffinity`                            | Setting this to `hard` enforces the [anti-affinity][] rules. If it is set to `soft` it will be done "best effort". Setting it to `custom` will use whatever is set in the `customAntiAffinity` parameter. Other values will be ignored.                                                                                                                                                                                                                                                                                            | `hard`                                                                                                          |
| `clusterName`                             | This will be used as the OpenSearch cluster name and should be unique per cluster in the namespace                                                                                                                                                                                                                                                                                                                                                                                                                                 | `opensearch-cluster`                                                                                            |
| `customAntiAffinity`                      | Allows passing in custom anti-affinity settings as defined in the [anti-affinity][] rules. Using this parameter requires setting the `antiAffinity` parameter to `custom`.                                                                                                                                                                                                                                                                                                                                                         | `{}`                                                                                                            |
| `enableServiceLinks`                      | Set to false to disabling service links, which can cause slow pod startup times when there are many services in the current namespace.                                                                                                                                                                                                                                                                                                                                                                                             | `true`                                                                                                          |
| `envFrom`                                 | Templatable string to be passed to the [environment from variables][] which will be appended to the `envFrom:` definition for the container                                                                                                                                                                                                                                                                                                                                                                                        | `[]`                                                                                                            |
| `config`                                  | Allows you to add any config files in `/usr/share/opensearch/config/` such as `opensearch.yml` and `log4j2.properties`. String or map format may be used for specifying content of each configuration file. In case of string format, the whole content of the config file will be replaced by new config file value when in case of using map format content of configuration file will be a result of merge. In both cases content passed through tpl. See [values.yaml][] for an example of the formatting (passed through tpl) | `{}`                                                                                                            |
| `opensearchJavaOpts`                      | Java options for OpenSearch. This is where you should configure the jvm heap size                                                                                                                                                                                                                                                                                                                                                                                                                                                  | `-Xmx512M -Xms512M`                                                                                             |
| `majorVersion`                            | Used to set major version specific configuration. If you are using a custom image and not running the default OpenSearch version you will need to set this to the version you are running (e.g. `majorVersion: 1`)                                                                                                                                                                                                                                                                                                                 | `""`                                                                                                            |
| `global.dockerRegistry`                   | Set if you want to change the default docker registry, e.g. a private one.                                                                                                                                                                                                                                                                                                                                                                                                                                                         | `""`                                                                                                            |
| `extraContainers`                         | Array of extra containers                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | `""`                                                                                                            |
| `extraEnvs`                               | Extra environments variables to be passed to OpenSearch services                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | `[]`                                                                                                            |
| `extraInitContainers`                     | Array of extra init containers                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | `[]`                                                                                                            |
| `extraVolumeMounts`                       | Array of extra volume mounts                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | `[]`                                                                                                            |
| `extraVolumes`                            | Array of extra volumes to be added                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | `[]`                                                                                                            |
| `fullnameOverride`                        | Overrides the `clusterName` and `nodeGroup` when used in the naming of resources. This should only be used when using a single `nodeGroup`, otherwise you will have name conflicts                                                                                                                                                                                                                                                                                                                                                 | `""`                                                                                                            |
| `hostAliases`                             | Configurable [hostAliases][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | `[]`                                                                                                            |
| `httpHostPort`                            | Expose another http-port as hostPort. Refer to documentation for more information and requirements about using hostPorts.                                                                                                                                                                                                                                                                                                                                                                                                          | `""`                                                                                                            |
| `httpPort`                                | The http port that Kubernetes will use for the healthchecks and the service. If you change this you will also need to set `http.port` in `extraEnvs`                                                                                                                                                                                                                                                                                                                                                                               | `9200`                                                                                                          |
| `image.pullPolicy`                        | The Kubernetes [imagePullPolicy][] value                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | `IfNotPresent`                                                                                                  |
| `imagePullSecrets`                        | Configuration for [imagePullSecrets][] so that you can use a private registry for your image                                                                                                                                                                                                                                                                                                                                                                                                                                       | `[]`                                                                                                            |
| `image.tag`                               | The OpenSearch Docker image tag                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | `1.0.0`                                                                                                         |
| `image.repository`                        | The OpenSearch Docker image                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | `opensearchproject/opensearch`                                                                                  |
| `ingress`                                 | Configurable [ingress][] to expose the OpenSearch service. See [values.yaml][] for an example                                                                                                                                                                                                                                                                                                                                                                                                                                      | see [values.yaml][]                                                                                             |
| `initResources`                           | Allows you to set the [resources][] for the `initContainer` in the StatefulSet                                                                                                                                                                                                                                                                                                                                                                                                                                                     | `{}`                                                                                                            |
| `keystore`                                | Allows you map Kubernetes secrets into the keystore.                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | `[]`                                                                                                            |
| `labels`                                  | Configurable [labels][] applied to all OpenSearch pods                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | `{}`                                                                                                            |
| `masterService`                           | The service name used to connect to the masters. You only need to set this if your master `nodeGroup` is set to something other than `master`                                                                                                                                                                                                                                                                                                                                                                                      | `""`                                                                                                            |
| `maxUnavailable`                          | The [maxUnavailable][] value for the pod disruption budget. By default this will prevent Kubernetes from having more than 1 unhealthy pod in the node group                                                                                                                                                                                                                                                                                                                                                                        | `1`                                                                                                             |
| `metricsPort`                             | The metrics port (for Performance Analyzer) that Kubernetes will use for the service.                                                                                                                                                                                                                                                                                                                                                                                                                                              | `9600`                                                                                                          |
| `nameOverride`                            | Overrides the `clusterName` when used in the naming of resources                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | `""`                                                                                                            |
| `networkHost`                             | Value for the `network.host OpenSearch setting`                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | `0.0.0.0`                                                                                                       |
| `networkPolicy.create`                    | Enable network policy creation for OpenSearch                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | `false`                                                                                                         |
| `nodeAffinity`                            | Value for the [node affinity settings][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | `{}`                                                                                                            |
| `nodeGroup`                               | This is the name that will be used for each group of nodes in the cluster. The name will be `clusterName-nodeGroup-X` , `nameOverride-nodeGroup-X` if a `nameOverride` is specified, and `fullnameOverride-X` if a `fullnameOverride` is specified                                                                                                                                                                                                                                                                                 | `master`                                                                                                        |
| `nodeSelector`                            | Configurable [nodeSelector][] so that you can target specific nodes for your OpenSearch cluster                                                                                                                                                                                                                                                                                                                                                                                                                                    | `{}`                                                                                                            |
| `persistence`                             | Enables a persistent volume for OpenSearch data.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | see [values.yaml][]                                                                                             |
| `persistence.enableInitChown`             | Disable the `fsgroup-volume` initContainer that will update permissions on the persistent disk.                                                                                                                                                                                                                                                                                                                                                                                                                                    | `true`                                                                                                          |
| `podAffinity`                             | Value for the [pod affinity settings][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | `{}`                                                                                                            |
| `podAnnotations`                          | Configurable [annotations][] applied to all OpenSearch pods                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | `{}`                                                                                                            |
| `podManagementPolicy`                     | By default Kubernetes [deploys StatefulSets serially][]. This deploys them in parallel so that they can discover each other                                                                                                                                                                                                                                                                                                                                                                                                        | `Parallel`                                                                                                      |
| `podSecurityContext`                      | Allows you to set the [securityContext][] for the pod                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | see [values.yaml][]                                                                                             |
| `podSecurityPolicy`                       | Configuration for create a pod security policy with minimal permissions to run this Helm chart with `create: true`. Also can be used to reference an external pod security policy with `name: "externalPodSecurityPolicy"`                                                                                                                                                                                                                                                                                                         | see [values.yaml][]                                                                                             |
| `priorityClassName`                       | The name of the [PriorityClass][]. No default is supplied as the PriorityClass must be created first                                                                                                                                                                                                                                                                                                                                                                                                                               | `""`                                                                                                            |
| `rbac`                                    | Configuration for creating a role, role binding and ServiceAccount as part of this Helm chart with `create: true`. Also can be used to reference an external ServiceAccount with `serviceAccountName: "externalServiceAccountName"`                                                                                                                                                                                                                                                                                                | see [values.yaml][]                                                                                             |
| `rbac.automountServiceAccountToken`       | Controls whether a service account token should be automatically mounted to the Pods.                                                                                                                                                                                                                                                                                                                                                                                                                                              | `true`                                                                                                          |
| `replicas`                                | Kubernetes replica count for the StatefulSet (i.e. how many pods)                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | `3`                                                                                                             |
| `resources`                               | Allows you to set the [resources][] for the StatefulSet                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | see [values.yaml][]                                                                                             |
| `roles`                                   | A list of the specific node [roles][] for the `nodeGroup`                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | see [values.yaml][]                                                                                             |
| `singleNode`                              | If `discovery.type` in the opensearch configuration is set to `"single-node"`, this should be set to `true`. If `true`, replicas will be forced to `1`.                                                                                                                                                                                                                                                                                                                                                                            | `false`                                                                                                         |
| `schedulerName`                           | Name of the [alternate scheduler][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | `""`                                                                                                            |
| `secretMounts`                            | Allows you easily mount a secret as a file inside the StatefulSet. Useful for mounting certificates and other secrets. See [values.yaml][] for an example                                                                                                                                                                                                                                                                                                                                                                          | `[]`                                                                                                            |
| `securityConfig`                          | Configure the opensearch security plugin. There are multiple ways to inject configuration into the chart, see [values.yaml][] details.                                                                                                                                                                                                                                                                                                                                                                                             | By default an insecure demonstration configuration is set. This **must** be changed before going to production. |
| `securityContext`                         | Allows you to set the [securityContext][] for the container                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | see [values.yaml][]                                                                                             |
| `service.annotations`                     | [LoadBalancer annotations][] that Kubernetes will use for the service. This will configure load balancer if `service.type` is `LoadBalancer`                                                                                                                                                                                                                                                                                                                                                                                       | `{}`                                                                                                            |
| `service.headless.annotations`            | Allow you to set annotations on the headless service                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | `{}`                                                                                                            |
| `service.externalTrafficPolicy`           | Some cloud providers allow you to specify the [LoadBalancer externalTrafficPolicy][]. Kubernetes will use this to preserve the client source IP. This will configure load balancer if `service.type` is `LoadBalancer`                                                                                                                                                                                                                                                                                                             | `""`                                                                                                            |
| `service.httpPortName`                    | The name of the http port within the service                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | `http`                                                                                                          |
| `service.labelsHeadless`                  | Labels to be added to headless service                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | `{}`                                                                                                            |
| `service.labels`                          | Labels to be added to non-headless service                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | `{}`                                                                                                            |
| `service.loadBalancerIP`                  | Some cloud providers allow you to specify the [loadBalancer][] IP. If the `loadBalancerIP` field is not specified, the IP is dynamically assigned. If you specify a `loadBalancerIP` but your cloud provider does not support the feature, it is ignored.                                                                                                                                                                                                                                                                          | `""`                                                                                                            |
| `service.loadBalancerSourceRanges`        | The IP ranges that are allowed to access                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | `[]`                                                                                                            |
| `service.metricsPortName`                 | The name of the metrics port (for Performance Analyzer) within the service                                                                                                                                                                                                                                                                                                                                                                                                                                                         | `metrics`                                                                                                       |
| `service.nodePort`                        | Custom [nodePort][] port that can be set if you are using `service.type: nodePort`                                                                                                                                                                                                                                                                                                                                                                                                                                                 | `""`                                                                                                            |
| `service.transportPortName`               | The name of the transport port within the service                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | `transport`                                                                                                     |
| `service.type`                            | OpenSearch [Service Types][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | `ClusterIP`                                                                                                     |
| `service.ipFamilyPolicy`                  | This sets the preferred ip addresses in case of a dual-stack server, there are three options [PreferDualStack, SingleStack, RequireDualStack], [more information on dual stack](https://kubernetes.io/docs/concepts/services-networking/dual-stack/)                                                                                                                                                                                                                                                                               | `""`                                                                                                            |
| `service.ipFamilies`                      | Sets the preferred IP variants and in which order they are preferred, the first family you list is used for the legacy .spec.ClusterIP field, [more information on dual stack](https://kubernetes.io/docs/concepts/services-networking/dual-stack/)                                                                                                                                                                                                                                                                                | `""`                                                                                                            |
| `sidecarResources`                        | Allows you to set the [resources][] for the sidecar containers in the StatefulSet                                                                                                                                                                                                                                                                                                                                                                                                                                                  | {}                                                                                                              |
| `sysctlInit`                              | Allows you to enable the `sysctlInit` to set sysctl vm.max_map_count through privileged `initContainer`.                                                                                                                                                                                                                                                                                                                                                                                                                           | `enabled: false`                                                                                                |
| `sysctlVmMaxMapCount`                     | Sets the [vm.max_map_count][] needed for OpenSearch                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | `262144`                                                                                                        |
| `terminationGracePeriod`                  | The [terminationGracePeriod][] in seconds used when trying to stop the pod                                                                                                                                                                                                                                                                                                                                                                                                                                                         | `120`                                                                                                           |
| `tolerations`                             | Configurable [tolerations][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | `[]`                                                                                                            |
| `topologySpreadConstraints`               | Configuration for pod [topologySpreadConstraints][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | `[]`                                                                                                            |
| `transportHostPort`                       | Expose another transport port as hostPort. Refer to documentation for more information and requirements about using hostPorts.                                                                                                                                                                                                                                                                                                                                                                                                     | `""`                                                                                                            |
| `transportPort`                           | The transport port that Kubernetes will use for the service. If you change this you will also need to set transport port configuration in `extraEnvs`                                                                                                                                                                                                                                                                                                                                                                              | `9300`                                                                                                          |
| `updateStrategy`                          | The [updateStrategy][] for the StatefulSet. By default Kubernetes will wait for the cluster to be green after upgrading each pod. Setting this to `OnDelete` will allow you to manually delete each pod during upgrades                                                                                                                                                                                                                                                                                                            | `RollingUpdate`                                                                                                 |
| `volumeClaimTemplate`                     | Configuration for the [volumeClaimTemplate for StatefulSets][]. You will want to adjust the storage (default `30Gi` ) and the `storageClassName` if you are using a different storage class                                                                                                                                                                                                                                                                                                                                        | see [values.yaml][]                                                                                             |
| `extraObjects`                            | Array of extra K8s manifests to deploy                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | list `[]`                                                                                                       |
| `livenessProbe`                           | Configuration fields for the liveness [probe][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | see [exampleLiveness][] in `values.yaml`                                                                        |
| `readinessProbe`                          | Configuration fields for the readiness [probe][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | see [exampleReadiness][] in `values.yaml`                                                                       |
| `startupProbe`                            | Configuration fields for the startup [probe][]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | see [exampleStartup][] in `values.yaml`                                                                         |
| `plugins.enabled`                         | Allow/disallow to add 3rd Party / Custom plugins not offered in the default OpenSearchDashboards image                                                                                                                                                                                                                                                                                                                                                                                                                             | false                                                                                                           |
| `plugins.installList`                     | Array containing the Opensearch Dashboards plugins to be installed in container                                                                                                                                                                                                                                                                                                                                                                                                                                                    | \[]                                                                                                             |
| `opensearchLifecycle`                     | Allows you to configure lifecycle hooks for the OpenSearch container in the StatefulSet                                                                                                                                                                                                                                                                                                                                                                                                                                            | {}                                                                                                              |
| `lifecycle`                               | Allows you to configure lifecycle hooks for the OpenSearch container in the StatefulSet                                                                                                                                                                                                                                                                                                                                                                                                                                            | {}                                                                                                              |
| `openSearchAnnotations`                   | Allows you to configure custom annotation in the StatefullSet of the OpenSearch container                                                                                                                                                                                                                                                                                                                                                                                                                                          | {}                                                                                                              |
| `serviceMonitor.enabled`                  | Enables the creation of a [ServiceMonitor] resource for Prometheus monitoring. Requires the Prometheus Operator to be installed in your Kubernetes cluster.                                                                                                                                                                                                                                                                                                                                                                        | `false`                                                                                                         |
| `serviceMonitor.path`                     | Path where metrics are exposed. Applicable only if `serviceMonitor.enabled` is set to `true`.                                                                                                                                                                                                                                                                                                                                                                                                                                      | `/_prometheus/metrics`                                                                                          |
| `serviceMonitor.interval`                 | Interval at which metrics should be scraped by Prometheus. Applicable only if `serviceMonitor.enabled` is set to `true`.                                                                                                                                                                                                                                                                                                                                                                                                           | `10s`                                                                                                           |
| `serviceMonitor.basicAuth.enabled`        | Wheter or not the serviceMonitor should use basic auth                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | `false`                                                                                                         |
| `serviceMonitor.basicAuth.existingSecret` | When using basicAuth for the serviceMonitor, use an existing secret                                                                                                                                                                                                                                                                                                                                                                                                                                                                | `""`                                                                                                            |
| `serviceMonitor.basicAuth.username`       | Username to be used for basic auth                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | `""`                                                                                                            |
| `serviceMonitor.basicAuth.password`       | Password to be used for basic auth                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | `""`                                                                                                            |
| `serviceMonitor.scheme`                   | scheme to be used for scraping the metrics                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | `"http"`                                                                                                        |
| `serviceMonitor.tlsConfig`                | optional tlsConfig to be used for scraping                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | `{}`                                                                                                            |

[anti-affinity]: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity
[environment from variables]: https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#configure-all-key-value-pairs-in-a-configmap-as-container-environment-variables
[values.yaml]: https://github.com/opensearch-project/helm-charts/blob/main/charts/opensearch/values.yaml
[hostAliases]: https://kubernetes.io/docs/concepts/services-networking/add-entries-to-pod-etc-hosts-with-host-aliases/
[imagepullPolicy]: https://kubernetes.io/docs/concepts/containers/images/#updating-images
[imagePullSecrets]: https://kubernetes.io/docs/tasks/configure-pod-container/pull-image-private-registry/
[ingress]: https://kubernetes.io/docs/concepts/services-networking/ingress/
[resources]: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/
[labels]: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/
[maxUnavailable]: https://kubernetes.io/docs/tasks/run-application/configure-pdb/#specifying-a-poddisruptionbudget
[node affinity settings]: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#node-affinity-beta-feature
[pod affinity settings]: https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#types-of-inter-pod-affinity-and-anti-affinity
[nodeSelector]: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#nodeselector
[annotations]: https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/
[deploys statefulsets serially]: https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#pod-management-policies
[securityContext]: https://kubernetes.io/docs/tasks/configure-pod-container/security-context/
[priorityClass]: https://kubernetes.io/docs/concepts/configuration/pod-priority-preemption/#priorityclass
[roles]: https://opensearch.org/docs/opensearch/cluster/
[alternate scheduler]: https://kubernetes.io/docs/tasks/administer-cluster/configure-multiple-schedulers/#specify-schedulers-for-pods
[loadBalancer annotations]: https://kubernetes.io/docs/concepts/services-networking/service/#ssl-support-on-aws
[loadBalancer externalTrafficPolicy]: https://kubernetes.io/docs/tasks/access-application-cluster/create-external-load-balancer/#preserving-the-client-source-ip
[loadBalancer]: https://kubernetes.io/docs/concepts/services-networking/service/#loadbalancer
[nodePort]: https://kubernetes.io/docs/concepts/services-networking/service/#nodeport
[vm.max_map_count]: https://opensearch.org/docs/opensearch/install/important-settings/
[terminationGracePeriod]: https://kubernetes.io/docs/concepts/workloads/pods/pod/#termination-of-pods
[tolerations]: https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/
[updateStrategy]: https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/
[volumeClaimTemplate for statefulsets]: https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#stable-storage
[service types]: https://kubernetes.io/docs/concepts/services-networking/service/#publishing-services-service-types
[topologySpreadConstraints]: https://kubernetes.io/docs/concepts/workloads/pods/pod-topology-spread-constraints
[probe]: https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#define-readiness-probes
[exampleStartup]: https://github.com/opensearch-project/helm-charts/blob/main/charts/opensearch/values.yaml#332
[exampleLiveness]: https://github.com/opensearch-project/helm-charts/blob/main/charts/opensearch/values.yaml#340
[exampleReadiness]: https://github.com/opensearch-project/helm-charts/blob/main/charts/opensearch/values.yaml#349
[ServiceMonitor]: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#servicemonitor
