Make /run/postgresql a volume

[md5]

Forgot I created this branch last week. Opening this PR for discussion as much as anything. It seems reasonable to me for service containers to use VOLUME /run/MYSERVICE if they have a dedicated /run directory.

Fixes #50

[md5]

FWIW, I was just able to start the existing postgres container like so:

docker run -d --read-only -v /tmp -v /run/postgresql postgres:9.4

[md5]

I just checked and saw that /tmp doesn't end up with a sticky bit when you do -v /tmp...

[md5]

See appropriate/docker-jetty#5 for how I'm thinking about approaching this in the jetty image.

[tianon]

The rest of this file has indented whitespace, doesn't it?

[md5]

55e0d60f920689ae97e9c953111af5f7ba9a01f3

[md5]

Actually, let me squash that.

[md5]

51283401e11bb5e6cb91c987dfd64a8fffa24653

[tianon]

This seems sane to me.

[tianon]

So, one thing that might make this less sane is that this can't be undone in images FROM this one, but I think we're reasonably isolated from that being a problem with this specific path.

[tianon]

LGTM

[yosifkit]

I am wary of merging this without more community input.

[md5]

I am wary of merging this without more community input.

I'm not in a rush to see this merged, but I do think it would fix the issue that @bartmeuris reported in #50.

I know that the pgsql-pkg-docker list hasn't seen much activity, but perhaps it would be worth posting something there.

[tianon]

ping @jpetazzo who's had strong feelings about VOLUME in the past 😈

[yosifkit]

As an alternative, we could just add the chown lines (fixing #50), and leave the VOLUME to the user if it is desired. But some community feedback would be best, even if they are indifferent on the change.

[md5]

@yosifkit good idea. I'll split out the chown changes into a separate PR and update (or just close) this one.

[md5]

I've updated this PR to be based on the branch in #52. Commit e616341 should drop out of this PR if that gets merged.

[yosifkit]

We should leave this open to allow further discussion to see if users want the volume by default or maybe we just need to document a simple -v /run/postgresql on the run and then volume sharing with --volumes-from. The only problem with the volumes-from approach is that the data directory is also shared, since there is no way to limit docker volume sharing.

[md5]

Looks like all work to improve the situation with --volumes-from is waiting on moby/moby#8484, which doesn't currently have a milestone, unfortunately.

[md5]

I also just came across moby/moby#8478, which mounts /run on tmpfs (found via docker-library/official-images#497 (comment)). It's unclear from my reading of that PR whether it would be possible to somehow access something like /run/postgresql from another container if that approach is taken.

[md5]

Github isn't picking up changes to this branch. I'm going to try closing and reopening the PR.

[md5]

So much for that...

[yosifkit]

I wonder if it has something to do with the disconnect from upstream repos? It seems that some have gone through and that the ones that were forked from us have been reparented to the base. @tianon is talking to support about it.

[md5]

I was expecting that after #52 closed, this PR would only have one commit (4df941f) since the other commit has been merged (e616341).

Instead, both commits stayed there and the diff was still showing changes from e616341, so I rebased off the latest master and force-pushed. The PR didn't pick up the new ref as I expected, but still showed the other two. Once I closed it, the "Reopen and comment" button was grayed out.

Odd.