Adds a Step to the Shrink and Delete actions which prevents those
actions from running on a leader index - all follower indices must first
unfollow the leader index before these actions can run. This prevents
the loss of history before follower indices are ready, which might
otherwise result in the loss of data.
This commit modifies the put follow index action to use a
CcrRepository when creating a follower index. It routes
the logic through the snapshot/restore process. A
wait_for_active_shards parameter can be used to configure
how long to wait before returning the response.
We inject an Unfollow action before Shrink because the Shrink action
cannot be safely used on a following index, as it may not be fully
caught up with the leader index before the "original" following index is
deleted and replaced with a non-following Shrunken index. The Unfollow
action will verify that 1) the index is marked as "complete", and 2) all
operations up to this point have been replicated from the leader to the
follower before explicitly disconnecting the follower from the leader.
Injecting an Unfollow action before the Rollover action is done mainly
as a convenience: This allow users to use the same lifecycle policy on
both the leader and follower cluster without having to explictly modify
the policy to unfollow the index, while doing what we expect users to
want in most cases.
Some steps, such as steps that delete, close, or freeze an index, may fail due to a currently running snapshot of the index. In those cases, rather than move to the ERROR step, we should retry the step when the snapshot has completed.
This change adds an abstract step (`AsyncRetryDuringSnapshotActionStep`) that certain steps (like the ones I mentioned above) can extend that will automatically handle a situation where a snapshot is taking place. When a `SnapshotInProgressException` is received by the listener wrapper, a `ClusterStateObserver` listener is registered to wait until the snapshot has completed, re-running the ILM action when no snapshot is occurring.
This also adds integration tests for these scenarios (thanks to @talevy in #37552).
Resolves#37541
This change adds the unfollow action for CCR follower indices.
This is needed for the shrink action in case an index is a follower index.
This will give the follower index the opportunity to fully catch up with
the leader index, pause index following and unfollow the leader index.
After this the shrink action can safely perform the ilm shrink.
The unfollow action needs to be added to the hot phase and acts as
barrier for going to the next phase (warm or delete phases), so that
follower indices are being unfollowed properly before indices are expected
to go in read-only mode. This allows the force merge action to execute
its steps safely.
The unfollow action has three steps:
* `wait-for-indexing-complete` step: waits for the index in question
to get the `index.lifecycle.indexing_complete` setting be set to `true`
* `wait-for-follow-shard-tasks` step: waits for all the shard follow tasks
for the index being handled to report that the leader shard global checkpoint
is equal to the follower shard global checkpoint.
* `pause-follower-index` step: Pauses index following, necessary to unfollow
* `close-follower-index` step: Closes the index, necessary to unfollow
* `unfollow-follower-index` step: Actually unfollows the index using
the CCR Unfollow API
* `open-follower-index` step: Reopens the index now that it is a normal index
* `wait-for-yellow` step: Waits for primary shards to be allocated after
reopening the index to ensure the index is ready for the next step
In the case of the last two steps, if the index in being handled is
a regular index then the steps acts as a no-op.
Relates to #34648
Co-authored-by: Martijn van Groningen <martijn.v.groningen@gmail.com>
Co-authored-by: Gordon Brown <gordon.brown@elastic.co>
