Editing OpenSearch Cluster Monitoring (section)

==== Web GUI ====
Most of the information needed to monitor the status of the cluster is available through the _cat API, but it is rather difficult to get out and is not always very easy to interpret.  Elastic developed a tool called '''Marvel''' for this purpose and later integrated it into the '''kibana''' dashboard/visualization tool.  Other tools exist, but one open source tool implements at least some of the functionality of '''Marvel''':  '''[https://github.com/lmenezes/cerebro Cerebro].'''  '''Cerebro''' runs as a web application and queries the cluster's public API (port 9200).  It displays the status of the nodes and the indices and provides an improved interface for accessing the rest of the API commands and interpreting the results in a more readable manner.

'''Cerebro''' can be configured to automatically connect to the target cluster, or allow connections to multiple clusters.  Authentication is primitive; HTTP Basic Authentication is available for the Cerebro user interface, and authentication to the cluster can use either basic or certificate authentication methods.

Installation methods include RPM/DEB for package management or tarball.  Configuration (including setting authentication methods for both users and clusters) is done by editing the configuration file at <code>/etc/cerebro/application.conf</code>.

To enable cerebro to use self-signed certs (or non-publsihed CAs)

I did the following :

in the application.conf ( with rpm at /etc/cerebro ), add the following to the end :
 play.ws.ssl {
   trustManager = {
     stores = [
       { type = "PEM", path = "/etc/cerebro/elastic-stack-ca.pem" }
     ]
   }
 }     
 play.ws.ssl.loose.acceptAnyCertificate=true

The .pem file is the CA cert in PEM format. You can probably also use the CA p12 file used to setup ES security, but then change the 'type = "PEM"' part to 'type = "pkcs12"' 

And (re)start Cerebro.