Postgres to run with logs on stdout

[verydemo]

postgresql.conf ; The configuration file can only be set to stderr. Is stdout ok? stderr is (err) red log in journald. priority

[wglambert]

stdout should be fine, docker logs will read from stderr/stdout

This is just the upstream default https://www.postgresql.org/docs/current/runtime-config-logging.html

The default is to log to stderr only.

[verydemo]

Thanks.
Starting log output goes to stderr? I want to all output to stdout. What should I do?

Starting log:

[wglambert]

It looks like Postgres only supports logging to stderr
But there's a workaround that seems to work by setting the log file to /proc/1/fd/1 (stdout of pid1)

log_destination = 'stderr'              # Valid values are combinations of
                                        # stderr, csvlog, syslog, and eventlog,
                                        # depending on platform.  csvlog
                                        # requires logging_collector to be on.

# This is used when logging to stderr:
logging_collector = on          # Enable capturing of stderr and csvlog
                                        # into log files. Required to be on for
                                        # csvlogs.
                                        # (change requires restart)

# These are only used if logging_collector is on:
log_directory = '/proc/1/fd/'                   # directory where log files are written,
                                                # can be absolute or relative to PGDATA
log_filename = '1'                              # log file name pattern,

Then running it with a line that adjusts the permissions of /proc/ (gleaned from our mongodb entrypoint )

$ docker run -d --name postgres -e POSTGRES_PASSWORD=pass -v "$PWD"/postgresql.conf:/etc/postgresql/postgresql.conf postgres bash -c 'chown --dereference postgres "/proc/$$/fd/1" "/proc/$$/fd/2"; exec docker-entrypoint.sh "$@"' -- -c 'config_file=/etc/postgresql/postgresql.conf'
472878e452f9431268b29b26b8b4268e28ce065da8e4ac665afa8a1fc24df6a4

This is the log output when filtering out stdout

$ docker logs postgres 1>/dev/null
initdb: warning: enabling "trust" authentication for local connections
You can change this by editing pg_hba.conf or using the option -A, or
--auth-local and --auth-host, the next time you run initdb.
2022-04-22 17:24:49.644 UTC [1] LOG:  redirecting log output to logging collector process
2022-04-22 17:24:49.644 UTC [1] HINT:  Future log output will appear in directory "/proc/1/fd".

And this is what it looks like when filtering out stderr

$ docker logs postgres 2>/dev/null
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

The database cluster will be initialized with locale "en_US.utf8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".

Data page checksums are disabled.

fixing permissions on existing directory /var/lib/postgresql/data ... ok
creating subdirectories ... ok
selecting dynamic shared memory implementation ... posix
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting default time zone ... Etc/UTC
creating configuration files ... ok
running bootstrap script ... ok
performing post-bootstrap initialization ... ok
syncing data to disk ... ok


Success. You can now start the database server using:

    pg_ctl -D /var/lib/postgresql/data -l logfile start

waiting for server to start....2022-04-22 17:24:49.358 UTC [49] LOG:  redirecting log output to logging collector process
2022-04-22 17:24:49.358 UTC [49] HINT:  Future log output will appear in directory "/proc/1/fd".
2022-04-22 17:24:49.358 UTC [49] LOG:  starting PostgreSQL 14.2 (Debian 14.2-1.pgdg110+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit
2022-04-22 17:24:49.359 UTC [49] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
2022-04-22 17:24:49.364 UTC [51] LOG:  database system was shut down at 2022-04-22 17:24:49 UTC
2022-04-22 17:24:49.368 UTC [49] LOG:  database system is ready to accept connections
 done
server started

/usr/local/bin/docker-entrypoint.sh: ignoring /docker-entrypoint-initdb.d/*

waiting for server to shut down....2022-04-22 17:24:49.518 UTC [49] LOG:  received fast shutdown request
2022-04-22 17:24:49.519 UTC [49] LOG:  aborting any active transactions
2022-04-22 17:24:49.521 UTC [49] LOG:  background worker "logical replication launcher" (PID 57) exited with exit code 1
2022-04-22 17:24:49.522 UTC [52] LOG:  shutting down
2022-04-22 17:24:49.530 UTC [49] LOG:  database system is shut down
 done
server stopped

PostgreSQL init process complete; ready for start up.

2022-04-22 17:24:49.644 UTC [1] LOG:  starting PostgreSQL 14.2 (Debian 14.2-1.pgdg110+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit
2022-04-22 17:24:49.644 UTC [1] LOG:  listening on IPv4 address "0.0.0.0", port 5432
2022-04-22 17:24:49.644 UTC [1] LOG:  listening on IPv6 address "::", port 5432
2022-04-22 17:24:49.646 UTC [1] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
2022-04-22 17:24:49.649 UTC [63] LOG:  database system was shut down at 2022-04-22 17:24:49 UTC
2022-04-22 17:24:49.654 UTC [1] LOG:  database system is ready to accept connections

[verydemo]

Thanks.
This solution is effective, The output still has the red log. priority =3

[wglambert]

Yeah, you might try asking over at the Docker Community Forums, Docker Community Slack, or Stack Overflow

But gonna close since this isn't an issue with the image