If a PostgreSQL instance was shut down while repmgrd was running, and
repmgrd was subsequently restarted (this chain of events could occur
during e.g. a server reboot), the node record will have been set to
"inactive". Previously, in this case repmgrd would refuse to start up.
However, as we can determine the node is running, it should normally
be no problem to automatically set the node record to "active".
The old behaviour can be restored by setting the new parameter
"repmgrd_exit_on_inactive_node" to "true".
RM19604.
Per proposal in GitHub #662, this patch attempts to synchronise each
repmgrd's primary reconnection attempts to prevent potential race
conditions. This relies on each node's clock being correcly
synchronised.
Currently this change is experimental and is not enabled by default.
It can be enabled by setting the repmgr.conf parameter
"reconnect_loop_sync".
As of PostgreSQL 13, changes to the fundamental replication
configuration can be applied with a simple SIGHUP, no restart
required.
In case the old behaviour is desired, i.e. a full restart to apply
the configuration changes, the new configuration parameter
"standby_follow_restart" can be set. This parameter has no effect
in PostgreSQL 12 and earlier.
In certain corner cases, it's possible repmgrd may end up monitoring
a standby which was a former primary, but the node record has not
yet been updated.
Previously repmgrd would abort the promotion with a cryptic message
about being unable to find a node record for node_id -1 (the
default value for an unknown node id).
This commit addes a new configuration option "always_promote", which
determines whether repmgrd should promote the node in this case.
The default is "false", to effectively maintain the existing behaviour.
Logging output has also been improved to make it clearer what has
happened when this situation occurs.
This expunges two large and cumbersome sets of if/else statements and
the T_CONFIGURATION_OPTIONS_INITIALIZER macro, all of which needed to
be kept in sync when adding/modifying configuration file parameters.
