This commit reworks the Sniffer component to simplify it and make it possible to test it.
In particular, it no longer takes out the host that failed when sniffing on failure, but rather relies on whatever the cluster returns. This is the result of some valid comments from #27985. Taking out one single host is too naive, hard to test and debug.
A new Scheduler abstraction is introduced to abstract the tasks scheduling away and make it possible to plug in any test implementation and take out timing aspects when testing.
Concurrency aspects have also been improved, synchronized methods are no longer required. At the same time, we were able to take #27697 and #25701 into account and fix them, especially now that we can more easily add tests.
Last but not least, unit tests are added for the Sniffer component, long overdue.
Closes#27697Closes#25701
This commit removes the http.enabled setting. While all real nodes (started with bin/elasticsearch) will always have an http binding, there are many tests that rely on the quickness of not actually needing to bind to 2 ports. For this case, the MockHttpTransport.TestPlugin provides a dummy http transport implementation which is used by default in ESIntegTestCase.
closes#12792
Currently, the only way to get the REST response for the `/_cluster/state`
call to return the `cluster_uuid` is to request the `metadata` metrics,
which is one of the most expensive response structures. However, external
monitoring agents will likely want the `cluster_uuid` to correlate the
response with other API responses whether or not they want cluster
metadata.
We had a number of awaitsFix links that weren't updated after the xpack
merge.
Where possible I changed the links to the new locations, but in some
circumstances the original ticket was closed (suggesting the awaitsfix
should be removed) or was otherwise unclear the status.
Luca Cavanna
Ryan Ernst
Chris Earle
Zachary Tong