Introduce log_destination=jsonlog

"jsonlog" is a new value that can be added to log_destination to provide
logs in the JSON format, with its output written to a file, making it
the third type of destination of this kind, after "stderr" and
"csvlog".  The format is convenient to feed logs to other applications.
There is also a plugin external to core that provided this feature using
the hook in elog.c, but this had to overwrite the output of "stderr" to
work, so being able to do both at the same time was not possible.  The
files generated by this log format are suffixed with ".json", and use
the same rotation policies as the other two formats depending on the
backend configuration.

This takes advantage of the refactoring work done previously in ac7c807,
bed6ed3, 8b76f89 and 2d77d83 for the backend parts, and 72b76f7 for the
TAP tests, making the addition of any new file-based format rather
straight-forward.

The documentation is updated to list all the keys and the values that
can exist in this new format.  pg_current_logfile() also required a
refresh for the new option.

Author: Sehrope Sarkuni, Michael Paquier
Reviewed-by: Nathan Bossart, Justin Pryzby
Discussion: https://postgr.es/m/CAH7T-aqswBM6JWe4pDehi1uOiufqe06DJWaU5=X7dDLyqUExHg@mail.gmail.com

1 files changed, 12 insertions, 8 deletions

diff --git a/src/bin/pg_ctl/t/004_logrotate.pl b/src/bin/pg_ctl/t/004_logrotate.pl
index e04331bfef..de6028760d 100644
--- a/src/bin/pg_ctl/t/004_logrotate.pl
+++ b/src/bin/pg_ctl/t/004_logrotate.pl
@@ -6,7 +6,7 @@ use warnings;
 
 use PostgreSQL::Test::Cluster;
 use PostgreSQL::Test::Utils;
-use Test::More tests => 10;
+use Test::More tests => 14;
 use Time::HiRes qw(usleep);
 
 # Extract the file name of a $format from the contents of
@@ -65,7 +65,7 @@ $node->init();
 $node->append_conf(
 	'postgresql.conf', qq(
 logging_collector = on
-log_destination = 'stderr, csvlog'
+log_destination = 'stderr, csvlog, jsonlog'
 # these ensure stability of test results:
 log_rotation_age = 0
 lc_messages = 'C'
@@ -96,11 +96,13 @@ note "current_logfiles = $current_logfiles";
 like(
 	$current_logfiles,
 	qr|^stderr log/postgresql-.*log
-csvlog log/postgresql-.*csv$|,
+csvlog log/postgresql-.*csv
+jsonlog log/postgresql-.*json$|,
 	'current_logfiles is sane');
 
-check_log_pattern('stderr', $current_logfiles, 'division by zero', $node);
-check_log_pattern('csvlog', $current_logfiles, 'division by zero', $node);
+check_log_pattern('stderr',  $current_logfiles, 'division by zero', $node);
+check_log_pattern('csvlog',  $current_logfiles, 'division by zero', $node);
+check_log_pattern('jsonlog', $current_logfiles, 'division by zero', $node);
 
 # Sleep 2 seconds and ask for log rotation; this should result in
 # output into a different log file name.
@@ -122,13 +124,15 @@ note "now current_logfiles = $new_current_logfiles";
 like(
 	$new_current_logfiles,
 	qr|^stderr log/postgresql-.*log
-csvlog log/postgresql-.*csv$|,
+csvlog log/postgresql-.*csv
+jsonlog log/postgresql-.*json$|,
 	'new current_logfiles is sane');
 
 # Verify that log output gets to this file, too
 $node->psql('postgres', 'fee fi fo fum');
 
-check_log_pattern('stderr', $new_current_logfiles, 'syntax error', $node);
-check_log_pattern('csvlog', $new_current_logfiles, 'syntax error', $node);
+check_log_pattern('stderr',  $new_current_logfiles, 'syntax error', $node);
+check_log_pattern('csvlog',  $new_current_logfiles, 'syntax error', $node);
+check_log_pattern('jsonlog', $new_current_logfiles, 'syntax error', $node);
 
 $node->stop();