added opensearch document page

docs/self-managed/platform-deployment/helm-kubernetes/guides/using-existing-elasticsearch.md

@@ -55,8 +55,6 @@ global:
     auth:
       username: <username>
       password: <password>
-      existingSecret:
-      existingSecretKey:
     url:
       protocol: https
       host: <elasticsearch host>

docs/self-managed/platform-deployment/helm-kubernetes/guides/using-existing-opensearch.md

@@ -0,0 +1,61 @@
+---
+id: using-aws-managed-opensearch
+title: "Using AWS Managed Opensearch"
+description: "Learn how to use an AWS managed opensearch instance in Camunda 8 Self-Managed deployment."
+---
+
+Camunda 8 Self-Managed has two different types of components: Camunda components (Operate, Optimize, Tasklist, etc.) and non-Camunda, dependency components (such as Keycloak and Elasticsearch). For more details, review the [architecture](../../../platform-architecture/overview.md) documentation for more information on the different types of applications.
+
+This guide steps through using an existing AWS managed opensearch instance. By default, [Helm chart deployment](../deploy.md) creates a new elassticsearch instance, but it's possible to use AWS managed opensearch instead.
+
+## Preparation
+
+### Authentication
+
+There are two layers of permissions with opensearch. IAM and Opensearch internal. If you would like to connect to Opensearch using IAM roles for service accounts (IRSA) then please also refer to this [page](../platforms/amazon-eks/irsa.md)
+
+Otherwise, if you wish to connect to AWS managed opensearch with basic auth the you can follow the example given below.
+
+## Values file
+
+The only change required to use AWS managed Opensearch is configuring the following values in the Camunda 8 Self-Managed Helm chart:
+
+### Connecting to AWS managed opensearch with basic auth.
+
+```yaml
+global:
+  elasticsearch:
+    enabled: false
+  opensearch:
+    enabled: true
+    auth:
+      username: <username>
+      password: <password>
+    url:
+      protocol: https
+      host: <elasticsearch host>
+      port: 443
+
+elasticsearch:
+  enabled: false
+```
+
+You must disable the internal elasticsearch component and the elasticsearch configuration for all components.
+
+If you do not wish to specify the username and password in plaintext within the values.yaml, you can use the following values instead:
+
+```yaml
+global:
+  elasticsearch:
+    auth:
+      existingSecret: <name of the already existing secret that includes the password>
+      existingSecretKey: <key of the password value within the already existing secret>
+```
+
+## Next Steps
+
+Then, use the custom values file to [deploy Camunda 8](../deploy.md) as usual.
+
+```sh
+helm install camunda camunda/camunda-platform -f existing-elasticsearch-values.yaml
+```