Perform a switchover by:
- stopping current primary node
- promoting this standby node to primary
- forcing previous primary node to follow this node
Caveats:
- repmgrd must not be running, otherwise it may
attempt a failover
(TODO: find some way of notifying repmgrd of planned
activity like this)
- currently only set up for two-node operation; any other
standbys will probably become downstream cascaded standbys
of the old primary once it's restarted
- as we're executing repmgr remotely (on the old primary),
we'll need the location of its configuration file; this
can be provided explicitly with -C/--remote-config-file,
otherwise repmgr will look in default locations on the
remote server
- this does not yet support "rewinding" stopped nodes
which will be unable to catch up with the primary
TODO:
- update help, docs
- make connection test timeouts/intervals configurable
Anyone needing them, particularly in a replication context, should
know what they're doing anyway.
See also: http://www.postgresql.org/docs/current/interactive/sql-createindex.html#AEN74175
"Also, changes to hash indexes are not replicated over streaming or file-based
replication after the initial base backup, so they give wrong answers to
queries that subsequently use them. For these reasons, hash index use is presently
discouraged."
Also refactor configuration file handling while we're at it.
Previously a configuration file would be ignored if it couldn't
be opened, however that is now treated as an error.
When parsing command line arguments in check_parameters_for_action(),
create warnings for paramters supplied but not required (e.g. -D/--data-dir
for MASTER REGISTER), rather than fail with error(s), as the
presence of the parameters won't cause any problems.
Errors will still be raised for required-but-missing parameters, of course.
* repmgr: add explicit --log-level flag, repurpose --verbose flag to
show extra detailed/repetitive output only (see item below too)
-> e0cbdd5b31
* debug output: show some repetitive output only if --verbose flag set to prevent
excessive log growth
-> 8ab1901a93
This should make it more likely that the actual primary is first
in the retrieved list, reducing the number of connections to
other nodes in the cluster which need to be made.
repmgr and particularly repmgrd currently produce substantial
amounts of log output. Much of this is only useful when troubleshooting
or debugging.
Previously the -v/--verbose option just forced the log level to
INFO. With repmgrd this is pretty pointless - just set the log
level in the configuration file. With repmgr the configuration
file can be overriden by the new -L/--log-level option.
-v/--verbose now provides an additional, chattier/pedantic level
of logging ("Opening *this* logfile", "Executing *this* query",
"running in *this* loop") which is helpful for understanding
repmgr/repmgrd's behaviour, particularly for troubleshooting.
What additional verbose logging is generated will of course a
also depends on the log level set, so e.g. someone trying to
work out which configuration file is actually being opened
can use '--log-level=INFO --verbose' without being bothered
by an avalanche of extra verbose debugging output.
-t/--terse option will silence certain non-essential output, at
the moment any HINTs.
Note that -v/--verbose and -t/--terse are not mutually exclusive
(suggestions for better names welcome).
When cloning a server without this option, and pg_start_backup() takes time
to complete, repmgr appears to hang and give no indication of what may
or may not be happening. The hint provides an explanation for any
delay and possible action which could be taken to mitigate it.
There are a few places where additional hints are written as log
output, usually LOG_NOTICE. Create an explicit function to provide
hints in a standardized manner; by storing the log level of the
previous logger call, we can ensure the hint is only displayed when
the log message itself would be.
Part of an ongoing effort to better control repmgr's logging output.
