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.
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).
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.
If freopen() fails, stderr is diverted to an undisclosed location
and it's not clear what is going on.
Also add an explicit notice announcing our intention to divert
logging output to a file.
Per #105.
Note that it might make sense to disable logfile output when
running the repmgr command line client as normally you'd expect
immediate feedback.
We had the problem that the log file appeared empty for a long time due
to file buffers. Thus we call fflush() after every log message so the
log file gets written out to disk quickly
