I'm new to Postgres.

I updated the Dockerfile I use and successfully installed Postgresql on it. (My image runs Ubuntu 16.04 and I'm using Postgres 9.6.)

Everything worked fine until I tried to move the database to a Volume with docker-compose (that was after making a copy of the container's folder with cp -R /var/lib/postgresql /somevolume/.)

The issue is that Postgres just keeps crashing, as witnessed by supervisord:

2017-07-26 18:55:38,346 INFO exited: postgresql (exit status 1; not expected)
2017-07-26 18:55:39,355 INFO spawned: 'postgresql' with pid 195
2017-07-26 18:55:40,430 INFO success: postgresql entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2017-07-26 18:55:40,763 INFO exited: postgresql (exit status 1; not expected)
2017-07-26 18:55:41,767 INFO spawned: 'postgresql' with pid 197
2017-07-26 18:55:42,841 INFO success: postgresql entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
2017-07-26 18:55:43,179 INFO exited: postgresql (exit status 1; not expected)
(and so on…)

Logs

It's not clear to me what's happening as /var/log/postgresql remains empty.

chown?

I suspect it has to do with the user. If I compare the data folder inside the container and the copy I made of it to the volume, the only difference is that the original is owned by postgres while the copy is owned by root.

I tried running chown -R postgres:postgres on the copy. The operation was performed successfully, however postmaster.pid remains owned by root and I think that would be the issue.

Questions

• How can I get more information about the cause of the crash?
• How can I make it so that postmaster.id be owned by postgres ?
• Should I consider running postgres with root instead?

Any hint welcome.

EDIT: links to the Dockerfile and the docker-compose.xml.