Replace _xpack/monitoring/* with _monitoring/* ES API calls

[ycombinator]

Starting 7.0, the _xpack/monitoring/* API endpoints in Elasticsearch will be deprecated in favor of monitoring/* API endpoints. We should update any references to the deprecated endpoints in the Logstash codebase and replace them with the new ones.

[jsvd]

Thanks for raising this, looking at the code we only seem to have two references to _xpack in the code (a few more in the tests):

% grep "['\"/]_xpack" x-pack/lib logstash-core/lib lib/ -r
x-pack/lib/license_checker/license_reader.rb:          response = client.get('_xpack')
x-pack/lib/template.cfg.erb:    bulk_path => "/_xpack/monitoring/_bulk?system_id=logstash&system_api_version=<%= system_api_version %>&interval=1s"

@ycombinator do you know if the license checks currently being done against /_xpack will be renamed too?

[ycombinator]

GET _xpack is going to stay as-is. However, we might want to separately consider switching the license check to use GET _license instead of GET _xpack if possible.

[jsvd]

fixed in #10528

[jsvd]

created #11382 to track the license checking path update