Sending RUN ["docker-entrypoint.sh", "postgres", "--version"] output to the console during the build

[doraemoncito]

Apologies if this question has been asked before. Up until version 10.10 you could see the output of the command in a Docker file that inherited from the postgres:10.10-alpine image. E.g. this Dockerfile (cut for brevity):

FROM postgres:10.10-alpine
RUN ["docker-entrypoint.sh", "postgres", "--version"]

would output something like this:

[INFO]  ---> fd92132d5c20
[INFO] Step 10/10 : RUN ["docker-entrypoint.sh", "postgres", "--version"]
[INFO] 
[INFO]  ---> Running in 2a64e24f8df8
[INFO] The files belonging to this database system will be owned by user "postgres".
[INFO] This user must also own the server process.
[INFO] 
[INFO] The database cluster will be initialized with locale "en_US.utf8".
[INFO] The default database encoding has accordingly been set to "UTF8".
[INFO] The default text search configuration will be set to "english".
...

Starting at 10.11 the output no longer appears in the console during the build. . E.g. this Dockerfile (again cut for brevity):

FROM postgres:12-alpine
RUN ["docker-entrypoint.sh", "postgres", "--version"]

Generates this output instead:

[INFO]  ---> 9e1c212f6bcc
[INFO] Step 10/10 : RUN ["docker-entrypoint.sh", "postgres", "--version"]
[INFO] 
[INFO]  ---> Running in aa64abc39508
[INFO] postgres (PostgreSQL) 12.2
[INFO] Removing intermediate container aa64abc39508
[INFO]  ---> e7eeb9d68edc
[INFO] Successfully built e7eeb9d68edc

Is there any way of getting the earlier 10.10 entry point output behaviour in later versions of the Docker image?

[tianon]

The output no longer appears because postgres --version no longer has the side effect of initializing a database (since the arguments passed to postgres are now passed to the temporary daemon as well, so it would've completely broken instead of doing what an interactive user would expect, so we changed it to explicitly detect several flags):

postgres/docker-entrypoint.sh

Lines 252 to 267 in a6d35fb

	# check arguments for an option that would cause postgres to stop
	# return true if there is one
	_pg_want_help() {
	local arg
	for arg; do
	case "$arg" in
	# postgres --help | grep 'then exit'
	# leaving out -C on purpose since it always fails and is unhelpful:
	# postgres: could not access the server configuration file "/var/lib/postgresql/data/postgresql.conf": No such file or directory
	-'?'|--help|--describe-config|-V|--version)
	return 0
	;;
	esac
	done
	return 1
	}

See #496 -- this is now possible to accomplish directly without hacks/workarounds like sed or --version. 👍

[doraemoncito]

https://github.com/docker-> See #496 -- this is now possible to accomplish directly without hacks/workarounds like sed or --version. 👍

Brilliant, that's exactly what I was looking for. Thank you.