[CM] Make the monitoring reloadable and configurable by CM.

[ph]

The beats can be configured to send the collected monitoring information to Elasticsearch, this option is globally set in the YAML config with the following:

xpack.monitoring:
  enabled: true
  elasticsearch:
    hosts: ["https://example.com:9200", "https://example2.com:9200"]
    username: beats_system
    password: somepassword

We have to do the following changes:

• Allow a beat to enable monitoring from CM.
• Allow to reconfigures monitoring in a running process. (Previously monitoring is set once at boot time.)
• Add a new type of config block to allow to reconfigure the monitoring from the manager.

Notes: The monitoring uses an internal pipeline so we may be able to reuse existing logic.

[ycombinator]

Note that now (with #9260 merged) Beats can ship their monitoring data directly to the monitoring Elasticsearch cluster. To do this, users must set the monitoring.* options instead of the xpack.monitoring.* options.

[michalpristas]

the question is, do we want to configure both options from CM?

[ph]

@ycombinator Thanks for the ping, looking at this, I believe the objective is to force the user to go with monitoring.* and not use xpack.monitoring.*. If this is the case I would just support the new way of defining it.

[ycombinator]

@ph you are correct, we will deprecate xpack.monitoring.* in favor of monitoring.* in the near future. I'm working on docs and config file updates now.

[ycombinator]

I'm working on docs and config file updates now.

Doc updates PR: #11678
Config file updates PR: #11677

[michalpristas]

closiong this one as well

cc @ph