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Configuring OpenSearch

Most OpenSearch configuration can take place in the cluster settings API. Certain operations require you to modify opensearch.yml and restart the cluster.

Whenever possible, use the cluster settings API instead; opensearch.yml is local to each node, whereas the API applies the setting to all nodes in the cluster. Certain settings, however, require opensearch.yml. In general, these settings relate to networking, cluster formation, and the local file system. To learn more, see Cluster formation.

Specify settings as environment variables

You can specify environment variables as arguments using -E when launching OpenSearch:

./opensearch -Ecluster.name=opensearch-cluster -Enode.name=opensearch-node1 -Ehttp.host=0.0.0.0 -Ediscovery.type=single-node

Update cluster settings using the API

The first step in changing a setting is to view the current settings:

GET _cluster/settings?include_defaults=true

For a more concise summary of non-default settings:

GET _cluster/settings

Three categories of setting exist in the cluster settings API: persistent, transient, and default. Persistent settings, well, persist after a cluster restart. After a restart, OpenSearch clears transient settings.

If you specify the same setting in multiple places, OpenSearch uses the following precedence:

1. Transient settings
2. Persistent settings
3. Settings from opensearch.yml
4. Default settings

To change a setting, just specify the new one as either persistent or transient. This example shows the flat settings form:

PUT _cluster/settings
{
  "persistent" : {
    "action.auto_create_index" : false
  }
}

You can also use the expanded form, which lets you copy and paste from the GET response and change existing values:

PUT _cluster/settings
{
  "persistent": {
    "action": {
      "auto_create_index": false
    }
  }
}

For more information about the Cluster Settings API, see Cluster settings.

Configuration file

You can find opensearch.yml in /usr/share/opensearch/config/opensearch.yml (Docker) or /etc/opensearch/opensearch.yml (most Linux distributions) on each node.

You can edit the OPENSEARCH_PATH_CONF=/etc/opensearch to change the config directory location. This variable is sourced from /etc/default/opensearch(Debian package) and /etc/sysconfig/opensearch(RPM package).

If you set your customized OPENSEARCH_PATH_CONF variable, be aware that other default environment variables will not be loaded.

You don’t mark settings in opensearch.yml as persistent or transient, and settings use the flat form:

cluster.name: my-application
action.auto_create_index: true
compatibility.override_main_response_version: true

The demo configuration includes a number of settings for the Security plugin that you should modify before using OpenSearch for a production workload. To learn more, see Security.

(Optional) CORS header configuration

If you are working on a client application running against an OpenSearch cluster on a different domain, you can configure headers in opensearch.yml to allow for developing a local application on the same machine. Use Cross Origin Resource Sharing so your application can make calls to the OpenSearch API running locally. Add the following lines in your custom-opensearch.yml file (note that the “-“ must be the first character in each line).

- http.host:0.0.0.0
- http.port:9200
- http.cors.allow-origin:"http://localhost"
- http.cors.enabled:true
- http.cors.allow-headers:X-Requested-With,X-Auth-Token,Content-Type,Content-Length,Authorization
- http.cors.allow-credentials:true