v11-0002-Add-a-new-argument-l-logdir-to-pg_createsubscrib.patch

From ca05dfade11209fdcfa4223a9fbb9d43814eda78 Mon Sep 17 00:00:00 2001
From: Gyan Sreejith <gyan.sreejith@gmail.com>
Date: Tue, 17 Mar 2026 19:10:28 -0400
Subject: [PATCH v11 2/3] Add a new argument -l <logdir> to
 pg_createsubscriber.

Enabling the option to write messages to log files in the specified directory.
A new directory is created if required. A subdirectory is created with timestamp as its name, and it will contain two new logfiles:
1. pg_createsubscriber_server.log  - captures messages related to starting and stopping the standby server.
2. pg_createsubscriber_internal.log - captures internal diagnostic output from pg_createsubscriber.

For example, if we specify -l abc as an argument, and if the timestamp on running it is 20260119T204317.204, a directory abc is created if it doesn't exist already, with 20260119T204317.204 as its subdirectory and it will contain the two log files pg_createsubscriber_server.log and pg_createsubscriber_internal.log
---
 doc/src/sgml/ref/pg_createsubscriber.sgml     |  28 +++
 src/bin/pg_basebackup/pg_createsubscriber.c   | 166 +++++++++++++++++-
 .../t/040_pg_createsubscriber.pl              |  41 ++++-
 3 files changed, 225 insertions(+), 10 deletions(-)

diff --git a/doc/src/sgml/ref/pg_createsubscriber.sgml b/doc/src/sgml/ref/pg_createsubscriber.sgml
index cf45ff3573d..2898a5ea111 100644
--- a/doc/src/sgml/ref/pg_createsubscriber.sgml
+++ b/doc/src/sgml/ref/pg_createsubscriber.sgml
@@ -136,6 +136,34 @@ PostgreSQL documentation
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><option>-l <replaceable class="parameter">directory</replaceable></option></term>
+     <term><option>--logdir=<replaceable class="parameter">directory</replaceable></option></term>
+     <listitem>
+      <para>
+       Specify the name of the log directory. A new directory is created with
+       this name if it does not exist. A subdirectory with a timestamp
+       indicating the time at which pg_createsubscriber was run will be created.
+       The following two log files will be created in the subdirectory with a
+       umask of 077 so that access is disallowed to other users by default.
+       <itemizedlist>
+        <listitem>
+         <para>
+          pg_createsubscriber_server.log which captures logs related to stopping
+          and starting the standby server,
+         </para>
+        </listitem>
+        <listitem>
+         <para>
+          pg_createsubscriber_internal.log which captures internal diagnostic
+          output (validations, checks, etc.)
+         </para>
+        </listitem>
+       </itemizedlist>
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><option>-n</option></term>
      <term><option>--dry-run</option></term>
diff --git a/src/bin/pg_basebackup/pg_createsubscriber.c b/src/bin/pg_basebackup/pg_createsubscriber.c
index b02af9a4cc0..87e4f95b22e 100644
--- a/src/bin/pg_basebackup/pg_createsubscriber.c
+++ b/src/bin/pg_basebackup/pg_createsubscriber.c
@@ -55,10 +55,14 @@
 #define INCLUDED_CONF_FILE			"pg_createsubscriber.conf"
 #define INCLUDED_CONF_FILE_DISABLED	INCLUDED_CONF_FILE ".disabled"
 
+#define SERVER_LOG_FILE_NAME "pg_createsubscriber_server"
+#define INTERNAL_LOG_FILE_NAME "pg_createsubscriber_internal"
+
 /* Command-line options */
 struct CreateSubscriberOptions
 {
 	char	   *config_file;	/* configuration file */
+	char	   *log_dir;		/* log directory name */
 	char	   *pub_conninfo_str;	/* publisher connection string */
 	char	   *socket_dir;		/* directory for Unix-domain socket, if any */
 	char	   *sub_port;		/* subscriber port number */
@@ -157,6 +161,9 @@ static void pg_createsub_log(enum pg_log_level, enum pg_log_part,
 			pg_attribute_printf(3, 4);
 pg_noreturn static void pg_fatal(const char *pg_restrict fmt,...)
 			pg_attribute_printf(1, 2);
+static void internal_log_file_write(enum pg_log_level level,
+									const char *pg_restrict fmt, va_list args)
+			pg_attribute_printf(2, 0);
 
 #define	WAIT_INTERVAL	1		/* 1 second */
 
@@ -178,6 +185,10 @@ static pg_prng_state prng_state;
 static char *pg_ctl_path = NULL;
 static char *pg_resetwal_path = NULL;
 
+static FILE *internal_log_file_fp = NULL;	/* File ptr to log all messages to */
+static char *log_timestamp = NULL;	/* Timestamp to be used in all log file
+									 * names */
+
 /* standby / subscriber data directory */
 static char *subscriber_dir = NULL;
 
@@ -192,7 +203,13 @@ pg_createsub_log(enum pg_log_level level, enum pg_log_part part,
 	va_list		args;
 
 	va_start(args, fmt);
-	pg_log_generic_v(level, part, fmt, args);
+
+	if (internal_log_file_fp != NULL)
+		internal_log_file_write(level, fmt, args);
+
+	if (internal_log_file_fp == NULL || level > PG_LOG_INFO)
+		pg_log_generic_v(level, part, fmt, args);
+
 	va_end(args);
 }
 
@@ -308,6 +325,12 @@ cleanup_objects_atexit(void)
 
 	if (standby_running)
 		stop_standby_server(subscriber_dir);
+
+	if (internal_log_file_fp != NULL)
+	{
+		fclose(internal_log_file_fp);
+		internal_log_file_fp = NULL;
+	}
 }
 
 static void
@@ -322,6 +345,7 @@ usage(void)
 			 "                                  databases and databases that don't allow connections\n"));
 	printf(_("  -d, --database=DBNAME           database in which to create a subscription\n"));
 	printf(_("  -D, --pgdata=DATADIR            location for the subscriber data directory\n"));
+	printf(_("  -l, --logdir=LOGDIR             location for the new log directory\n"));
 	printf(_("  -n, --dry-run                   dry run, just show what would be done\n"));
 	printf(_("  -p, --subscriber-port=PORT      subscriber port number (default %s)\n"), DEFAULT_SUB_PORT);
 	printf(_("  -P, --publisher-server=CONNSTR  publisher connection string\n"));
@@ -756,6 +780,7 @@ modify_subscriber_sysid(const struct CreateSubscriberOptions *opt)
 	bool		crc_ok;
 	struct timeval tv;
 
+	char	   *out_file;
 	char	   *cmd_str;
 
 	pg_createsub_log(PG_LOG_INFO, PG_LOG_PRIMARY,
@@ -794,8 +819,13 @@ modify_subscriber_sysid(const struct CreateSubscriberOptions *opt)
 		pg_createsub_log(PG_LOG_INFO, PG_LOG_PRIMARY,
 						 "running pg_resetwal on the subscriber");
 
-	cmd_str = psprintf("\"%s\" -D \"%s\" > \"%s\"", pg_resetwal_path,
-					   subscriber_dir, DEVNULL);
+	if (opt->log_dir != NULL)
+		out_file = psprintf("%s/%s/%s.log", opt->log_dir, log_timestamp, SERVER_LOG_FILE_NAME);
+	else
+		out_file = DEVNULL;
+
+	cmd_str = psprintf("\"%s\" -D \"%s\" >> \"%s\"", pg_resetwal_path,
+					   subscriber_dir, out_file);
 
 	pg_createsub_log(PG_LOG_DEBUG, PG_LOG_PRIMARY,
 					 "pg_resetwal command is: %s", cmd_str);
@@ -1018,6 +1048,110 @@ server_is_in_recovery(PGconn *conn)
 	return ret == 0;
 }
 
+static void
+internal_log_file_write(enum pg_log_level level, const char *pg_restrict fmt,
+						va_list args)
+{
+	if (level < __pg_log_level)
+		return;
+
+	if (internal_log_file_fp == NULL)
+		return;
+
+	vfprintf(internal_log_file_fp, fmt, args);
+
+	fprintf(internal_log_file_fp, "\n");
+	fflush(internal_log_file_fp);
+}
+
+/*
+ * Open a new logfile with proper permissions.
+ * From src/backend/postmaster/syslogger.c
+ */
+static FILE *
+logfile_open(const char *filename, const char *mode)
+{
+	FILE	   *fh;
+	mode_t		oumask;
+
+	oumask = umask((mode_t) ((~(S_IRUSR | S_IWUSR)) & (S_IRWXU | S_IRWXG | S_IRWXO)));
+	fh = fopen(filename, mode);
+	umask(oumask);
+
+	if (fh)
+	{
+		setvbuf(fh, NULL, PG_IOLBF, 0);
+
+#ifdef WIN32
+		/* use CRLF line endings on Windows */
+		_setmode(_fileno(fh), _O_TEXT);
+#endif
+	}
+	else
+		pg_fatal("could not open log file \"%s\": %m",
+				 filename);
+
+	return fh;
+}
+
+static void
+make_dir(const char *dir)
+{
+	struct stat statbuf;
+
+	if (stat(dir, &statbuf) == 0)
+		return;
+
+	if (errno != ENOENT)
+		pg_fatal("could not stat directory \"%s\": %m", dir);
+
+	if (mkdir(dir, S_IRWXU) == 0)
+	{
+		pg_log_info("directory %s created", dir);
+		return;
+	}
+
+	pg_fatal("could not create log directory \"%s\": %m", dir);
+}
+
+static void
+make_output_dirs(const char *log_dir)
+{
+	char		timestamp[128];
+	struct timeval tval;
+	time_t		now;
+	struct tm	tmbuf;
+	char		timestamp_dir[MAXPGPATH];
+	int			len;
+
+	/* Generate timestamp */
+	gettimeofday(&tval, NULL);
+	now = tval.tv_sec;
+
+	strftime(timestamp, sizeof(timestamp), "%Y%m%dT%H%M%S",
+			 localtime_r(&now, &tmbuf));
+
+	/* append milliseconds */
+	snprintf(timestamp + strlen(timestamp),
+			 sizeof(timestamp) - strlen(timestamp), ".%03u",
+			 (unsigned int) (tval.tv_usec / 1000));
+
+	log_timestamp = pg_strdup(timestamp);
+
+	/* Create base directory (ignore if exists) */
+	make_dir(log_dir);
+
+	/* Build timestamp directory path */
+	len = snprintf(timestamp_dir, MAXPGPATH, "%s/%s", log_dir, timestamp);
+
+	if (len >= MAXPGPATH)
+		pg_fatal("directory path for log files, %s/%s, is too long",
+				 log_dir, timestamp);
+
+	/* Create timestamp directory */
+	make_dir(timestamp_dir);
+}
+
 /*
  * Is the primary server ready for logical replication?
  *
@@ -1776,6 +1910,9 @@ start_standby_server(const struct CreateSubscriberOptions *opt, bool restricted_
 	if (restrict_logical_worker)
 		appendPQExpBufferStr(pg_ctl_cmd, " -o \"-c max_logical_replication_workers=0\"");
 
+	if (opt->log_dir != NULL)
+		appendPQExpBuffer(pg_ctl_cmd, " -l %s/%s/%s.log", opt->log_dir, log_timestamp, SERVER_LOG_FILE_NAME);
+
 	pg_createsub_log(PG_LOG_DEBUG, PG_LOG_PRIMARY,
 					 "pg_ctl command is: %s", pg_ctl_cmd->data);
 	rc = system(pg_ctl_cmd->data);
@@ -2346,6 +2483,7 @@ main(int argc, char **argv)
 		{"all", no_argument, NULL, 'a'},
 		{"database", required_argument, NULL, 'd'},
 		{"pgdata", required_argument, NULL, 'D'},
+		{"logdir", required_argument, NULL, 'l'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"subscriber-port", required_argument, NULL, 'p'},
 		{"publisher-server", required_argument, NULL, 'P'},
@@ -2404,6 +2542,7 @@ main(int argc, char **argv)
 	/* Default settings */
 	subscriber_dir = NULL;
 	opt.config_file = NULL;
+	opt.log_dir = NULL;
 	opt.pub_conninfo_str = NULL;
 	opt.socket_dir = NULL;
 	opt.sub_port = DEFAULT_SUB_PORT;
@@ -2434,7 +2573,7 @@ main(int argc, char **argv)
 
 	get_restricted_token();
 
-	while ((c = getopt_long(argc, argv, "ad:D:np:P:s:t:TU:v",
+	while ((c = getopt_long(argc, argv, "ad:D:l:np:P:s:t:TU:v",
 							long_options, &option_index)) != -1)
 	{
 		switch (c)
@@ -2455,6 +2594,10 @@ main(int argc, char **argv)
 				subscriber_dir = pg_strdup(optarg);
 				canonicalize_path(subscriber_dir);
 				break;
+			case 'l':
+				opt.log_dir = pg_strdup(optarg);
+				canonicalize_path(opt.log_dir);
+				break;
 			case 'n':
 				dry_run = true;
 				break;
@@ -2525,6 +2668,18 @@ main(int argc, char **argv)
 		}
 	}
 
+	if (opt.log_dir != NULL)
+	{
+		char	   *internal_log_file;
+
+		make_output_dirs(opt.log_dir);
+		internal_log_file = psprintf("%s/%s/%s.log", opt.log_dir, log_timestamp,
+									 INTERNAL_LOG_FILE_NAME);
+
+		if ((internal_log_file_fp = logfile_open(internal_log_file, "a")) == NULL)
+			pg_fatal("could not open log file \"%s\": %m", internal_log_file);
+	}
+
 	/* Validate that --all is not used with incompatible options */
 	if (opt.all_dbs)
 	{
@@ -2821,5 +2976,8 @@ main(int argc, char **argv)
 	pg_createsub_log(PG_LOG_INFO, PG_LOG_PRIMARY,
 					 "Done!");
 
+	if (internal_log_file_fp != NULL)
+		fclose(internal_log_file_fp);
+
 	return 0;
 }
diff --git a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
index 0c27fca7bb7..4ddfb621a5d 100644
--- a/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
+++ b/src/bin/pg_basebackup/t/040_pg_createsubscriber.pl
@@ -14,6 +14,7 @@ program_version_ok('pg_createsubscriber');
 program_options_handling_ok('pg_createsubscriber');
 
 my $datadir = PostgreSQL::Test::Utils::tempdir;
+my $logdir = PostgreSQL::Test::Utils::tempdir + "/logdir";
 
 # Generate a database with a name made of a range of ASCII characters.
 # Extracted from 002_pg_upgrade.pl.
@@ -362,9 +363,35 @@ command_ok(
 		'--subscription' => 'sub2',
 		'--database' => $db1,
 		'--database' => $db2,
+		'--logdir' => $logdir,
 	],
 	'run pg_createsubscriber --dry-run on node S');
 
+# Check that the log files were created
+my @server_log_files = glob "$logdir/*/pg_createsubscriber_server.log";
+is( scalar(@server_log_files), 1, "
+    pg_createsubscriber_server.log file was created");
+my $server_log_file_size = -s $server_log_files[0];
+isnt($server_log_file_size, 0,
+	"pg_createsubscriber_server.log file not empty");
+my $server_log = slurp_file($server_log_files[0]);
+like(
+	$server_log,
+	qr/consistent recovery state reached/,
+	"server reached consistent recovery state");
+
+my @internal_log_files = glob "$logdir/*/pg_createsubscriber_internal.log";
+is( scalar(@internal_log_files), 1, "
+    pg_createsubscriber_internal.log file was created");
+my $internal_log_file_size = -s $internal_log_files[0];
+isnt($internal_log_file_size, 0,
+	"pg_createsubscriber_internal.log file not empty");
+my $internal_log = slurp_file($internal_log_files[0]);
+like(
+	$internal_log,
+	qr/target server reached the consistent state/,
+	"log shows consistent state reached");
+
 # Check if node S is still a standby
 $node_s->start;
 is($node_s->safe_psql('postgres', 'SELECT pg_catalog.pg_is_in_recovery()'),
@@ -444,7 +471,8 @@ is(scalar(() = $stderr =~ /would create subscription/g),
 
 # Create a user-defined publication, and a table that is not a member of that
 # publication.
-$node_p->safe_psql($db1, qq(
+$node_p->safe_psql(
+	$db1, qq(
 	CREATE PUBLICATION test_pub3 FOR TABLE tbl1;
 	CREATE TABLE not_replicated (a int);
 ));
@@ -540,8 +568,7 @@ second row
 third row),
 	"logical replication works in database $db1");
 $result = $node_s->safe_psql($db1, 'SELECT * FROM not_replicated');
-is($result, qq(),
-	"table is not replicated in database $db1");
+is($result, qq(), "table is not replicated in database $db1");
 
 # Check result in database $db2
 $result = $node_s->safe_psql($db2, 'SELECT * FROM tbl2');
@@ -555,8 +582,10 @@ my $sysid_s = $node_s->safe_psql('postgres',
 isnt($sysid_p, $sysid_s, 'system identifier was changed');
 
 # Verify that pub2 was created in $db2
-is($node_p->safe_psql($db2, "SELECT COUNT(*) FROM pg_publication WHERE pubname = 'pub2'"),
-	'1', "publication pub2 was created in $db2");
+is( $node_p->safe_psql(
+		$db2, "SELECT COUNT(*) FROM pg_publication WHERE pubname = 'pub2'"),
+	'1',
+	"publication pub2 was created in $db2");
 
 # Get subscription and publication names
 $result = $node_s->safe_psql(
@@ -581,7 +610,7 @@ $result = $node_s->safe_psql(
     )
 );
 
-is($result, qq($db1|{test_pub3}
+is( $result, qq($db1|{test_pub3}
 $db2|{pub2}),
 	"subscriptions use the correct publications");
 
-- 
2.47.3