* Creates a prerequisites section in the cross-cluster replication (CCR)
overview.
* Adds concise definitions for local and remote cluster in a CCR context.
* Documents that the ES version of the local cluster must be the same
or a newer compatible version as the remote cluster.
We added docs for proxy mode in #40281 but on reflection we should not be
documenting this setting since it does not play well with all proxies and we
can't recommend its use. This commit removes those docs and expands its Javadoc
instead.
The example to delete a remote cluster is missing the `skip_unavailable` setting which results in an error:
```
"type": "illegal_argument_exception",
"reason": "missing required setting [cluster.remote.tiny-test.seeds] for setting [cluster.remote.tiny-test.skip_unavailable]"
```
In #33062 we introduced the `cluster.remote.*.proxy` setting for proxied
connections to remote clusters, but left it deliberately undocumented since it
needed followup work so that it could work with SNI. However, since #32517 is
now closed we can add this documentation and remove the comment about its lack
of documentation.
This commit clarifies how the gateway selection works when configuring
remote clusters for CCR or CCS. Specifically, it clarifies compatibility
between different versions which is a very common question.
Currently remote compression and ping schedule settings are dynamic.
However, we do not listen for changes. This commit adds listeners for
changes to those two settings. Additionally, when those settings change
we now close existing connections and open new ones with the settings
applied.
Fixes#37201.
This is related to #36652. In 7.0 we plan to deprecate a number of
settings that make reference to the concept of a tcp transport. We
mostly just have a single transport type now (based on tcp). Settings
should only reference tcp if they are referring to socket options. This
commit updates the settings in the docs. And removes string usages of
the old settings. Additionally it adds a missing remote compress setting
to the docs.
When we connect to remote clusters, there may be a few more routers/firewalls in-between compared to when we connect to nodes in the same cluster. We've experienced cases where firewalls drop connections completely and keep-alives seem not to be enough, or they are not properly configured. With this commit we allow to enable application-level pings specifically from CCS nodes to the selected remote nodes through the new setting `cluster.remote.${clusterAlias}.transport.ping_schedule`. The new setting is similar `transport.ping_schedule` but it does not affect intra-cluster communication, pings are only sent to specific remote cluster when specifically enabled, as they are disabled by default.
Relates to #34405
With remote clusters taking on a larger role, we have make the
infrastructure more generic than being tied to cross-cluster search
(CCS). We want to refer to the remote clusters configuration in the
cross-cluster replication (CCR) docs. Yet, these docs are still tied to
CCS. This commit extracts the remote clusters docs from CCS (with some
wording changes to make them more general) so that we can refer to them
in the CCR docs.
James Rodewig
Lisa Cawley
David Turner
Akshesh Doshi
Colin Goodheart-Smithe
Luca Cavanna
Melori Arellano
Tim Brooks
Jason Tedor