If you want Metricbeat to connect to a cluster that has X-Pack Security enabled, there are extra configuration steps.

To send data to a secured cluster through the elasticsearch output, Metricbeat needs to authenticate as a user who can manage index templates, monitor the cluster, create indices, and read, and write to the indices it creates. See Configuring Authentication Credentials for Metricbeat.

If encryption is enabled on the cluster, you also need to enable HTTPS in the Metricbeat configuration. See Configuring Metricbeat to use Encrypted Connections.

In addition to configuring authentication credentials for the Metricbeat itself, you need to grant authorized users permission to access the indices it creates. See Granting Users Access to Metricbeat Indices.

For more information about X-Pack Security, see Securing Elasticsearch and Kibana.