When running dokku in Docker backup fails unless host /tmp directory is mounted #374
Description
I'm running dokku in a Docker container as described in the docs and was trying to get Postgres backup working, but found that the tgz files being uploaded to S3 contained only an empty backup directory and no data.
I eventually figured out that that this was because during the backup process the data was being written to a directory under /tmp in the main dokku container, and then the s3backup container gets started with a path under the host's /tmp directory mounted, which is empty.
Adding an entry under volumes in my docker-compose.yml for the dokku container with - /tmp:/tmp solved the problem, but it took a while to get there. I'm not sure if there's a fix, or whether a note in the documentation might be more appropriate, but leaving this here in case anyone encounters the same issue.