This allows to set whether a particular permanent replication slot should always be created ('cluster_type=any', the default), or just on a primary ('cluster_type=primary') or standby ('cluster_type=standby') cluster, respectively.
When a replication slot is not registered with Patroni but is active, Patroni would log an error during each HA cycle in certain conditions (after a restart or role change). To avoid this, first check if the replication slot we are about to drop is still active and if so, only log a warning. Otherwise, log the slot we are dropping for informational purposes.
Close: #2499
Otherwise, the etcd (not etcd3) behave tests fail to connect:
```
Jan 02 09:56:18 HOOK-ERROR in before_all: AssertionError: etcd instance is not available for queries after 5 seconds
```
This adds a paragraph to the Standby Cluster section clarifying that the standby cluster is independent of the primary cluster and not visible from the primary cluster's Patroni interface.
Close#2090
This allows to have multiple hosts in a standby_cluster and ensures that the standby leader follows the main cluster's new leader after a switchover.
Partially addresses #2189
Sphinx' add_stylesheet() has been deprecated for a long time and got removed in recent versions of sphinx. If available, use add_css_file() instead.
Close#2079.
This field notes the last time (as unix epoch) a cluster member has successfully communicated with the DCS. This is useful to identify and/or analyze network partitions.
Also, expose dcs_last_seen in the MemberStatus class and its from_api_response() method.
This adds the `selector` to the Patroni Kubernetes StatefulSet spec
Without it, one gets errors like
```
error: error validating "patroni_k8s.yaml": error validating data: ValidationError(StatefulSet.spec): missing required field "selector" in io.k8s.api.apps.v1.StatefulSetSpec; if you choose to ignore these errors, turn validation off with --validate=false
```
(as mentioned in #1867)
