Rather than parse the configuration file into a new structure and
copy changed values from that into the main structure, we'll copy
the existing structure before parsing the changed configuration
file directly into the nmain structure, and revert using the copy
if any issues are encountered.
This is necessary as preparation for further reworking of the
configuration file structure handling. It also makes the reload
idempotent.
While we're at it, make some general improvements to the reload
handling, particularly:
- improve logging to show "before" and "after" values
- collate change notifications and only display if no errors
were found
- remove unnecessary double-logging of errors
- various bugfixes
The string in question will be generated internally by repmgr as a simple
one-line string with no control characters etc., so all that needs to be
escaped at the moment are any double quotes.
pg_rewind will only be executed on a demoted primary if explictly
requested, to prevent transactions on the primary, which
were never replicated, from being automatically overwritten.
If --force-rewind is provided, we'll need to check pg_rewind
is actually useable before we need to use it.
