Create mongodb home dir in useradd command

[ebolingerjc]

Updates Dockerfile with useradd -m command.

Fixes issue #323.

Users are annoyed when container commands try to save shell history and produce this message:

Error saving history file: FileOpenFailed: Unable to open() file /home/mongodb/.dbshell: No such file or directory

Users create brittle workarounds when the Dockerfile should just create the home directory when creating the mongodb user.

[yosifkit]

Rather than creating a home directory for a system account, we should probably just set it somewhere that mongodb can write, like /tmp.

Like this:

Suggested change

	RUN groupadd -r mongodb && useradd -m -r -g mongodb mongodb
	RUN groupadd -r mongodb && useradd --home-dir /tmp -r -g mongodb mongodb

Or this?
(fully expand the arguments for clarity; adjust now-edited RUN line to match semicolon formatting of other lines)

Suggested change

	RUN groupadd -r mongodb && useradd -m -r -g mongodb mongodb
	RUN set -eux; \
	groupadd --system mongodb; \
	useradd --system --gid mongodb --home-dir /tmp mongodb

Maybe even add --gid and --uid with explicit number 999 (the current value) like docker-library/postgres#93 to groupadd and useradd, respectively.

[yosifkit]

Or maybe we just add ENV HOME /tmp so that any UID that the user runs as will work.

[ebolingerjc]

How about a home-dir of /var/mongodb, similar to other system accounts?

> docker run mongo cut -d: -f 6,1 /etc/passwd | sort -t : -k 2
bin:/bin
proxy:/bin
sync:/bin
sys:/dev
mongodb:/home/mongodb
_apt:/nonexistent
nobody:/nonexistent
root:/root
games:/usr/games
daemon:/usr/sbin
backup:/var/backups
man:/var/cache/man
gnats:/var/lib/gnats
list:/var/list
mail:/var/mail
irc:/var/run/ircd
lp:/var/spool/lpd
news:/var/spool/news
uucp:/var/spool/uucp
www-data:/var/www

[ebolingerjc]

Still need to create the home directory to address the original issue.
The mongodb user ID should not share a global HOME env var with any other accounts.

[murphyj]

Hi - this still appears to be a problem in the latest version 4.4.6 I'm using.

We're using it in conjunction with MongoDB TestContainers. Will try a workaround to create the TestContainer using docker compose though this obviously isn't the cleanest workaround.

Any ideas when this will be merged?

[tianon]

As noted in #323, we're still looking for a reliable reproducer of an error:

From what I've seen, the error doesn't prevent anything from working, so it's really more of a warning -- is someone else seeing behavior different from that?

[tianon]

Fixed via #541 👍