Selfhosted @lemmy.world shaked_coffee @feddit.it 4w ago

Postgres backup script not working when executed by a cronjob

I've made the following backup script for my immich stack to be automatically run every day

# Load variables from the .env file
SCRIPT_DIR="$(dirname "$(readlink -f "$0")")"
set -a
source "$SCRIPT_DIR/../.env"
set +a

# Create a dump of the database and back it up
docker exec -it immich_db pg_dumpall -c -U immich > immich/latest_db_dump.sql
rustic -r $BUCKET_NAME/immich backup immich/latest_db_dump.sql --password=$REPO_PWD

# Backup the library, uploads and profile folders from the upload volume
rustic -r $BUCKET_NAME/immich backup immich/uploads_v/library --password=$REPO_PWD
rustic -r $BUCKET_NAME/immich backup immich/uploads_v/upload --password=$REPO_PWD
rustic -r $BUCKET_NAME/immich backup immich/uploads_v/profile --password=$REPO_PWD

# Apply forget policy
rustic -r $BUCKET_NAME/immich forget $RUSTIC_FORGET_POLICY --password=$REPO_PWD

and when I test it everything works properly, and the created sql dump file is complete and properly backed up.

However, when the execution is triggered automatically by a cronjob (as specified in this crontab line)

"30 3 * * *    root    /home/admin/WinguRepo/scripts/docker_backupper.sh"

(the line is taken from the nixos configuration file, that's why it also contains the user executing the operation)

it seems something breaks in the dumping process, because the script completes successfully but the sql dump file is an empty file (as can be noticed in the following output of rustic -r myrepo snapshots

snapshots for (host [wingu-box], label [], paths [immich/latest_db_dump.sql])
| ID       | Time                | Host      | Label | Tags | Paths                     | Files | Dirs |      Size |
|----------|---------------------|-----------|-------|------|---------------------------|-------|------|-----------|
| 10a32a83 | 2025-01-06 20:56:48 | wingu-box |       |      | immich/latest_db_dump.sql |     1 |    2 | 264.6 MiB |
| 1174bc2e | 2025-01-07 12:50:36 | wingu-box |       |      | immich/latest_db_dump.sql |     1 |    2 | 264.6 MiB |
| 00977334 | 2025-01-08 03:31:24 | wingu-box |       |      | immich/latest_db_dump.sql |     1 |    2 |       0 B |
| 513fffa1 | 2025-01-10 03:31:25 | wingu-box |       |      | immich/latest_db_dump.sql |     1 |    2 |       0 B |
4 snapshot(s)

(the first two snapshots were manually triggered by me executing the script, the latter two instead are triggered automatically by the cronjob)

Any idea about what is causing this behavior?

EDIT: Solution found thank's to @farcaller@fstab.sh comment:

You don’t need -it because you don’t run an interactive session in docker. It might be failing because you ask for a pseudoterminal in an environment where it doesn’t make sense.

7 comments

You don’t need -it because you don’t run an interactive session in docker. It might be failing because you ask for a pseudoterminal in an environment where it doesn’t make sense.
- Oh you are right, thank you. I've tried removing it and see if it fixes the issue 🤞
  
  IT WORKED! Thank yoy again for the help :)
Add set -x and dump the output (both stdout, stderr) into a logfile

Usually issues with crontab are related to variables ( PATH) as well, so you might want to consider verifying that.
- I've tried first removing the -it flag as suggested by @farcaller@fstab.sh in another comment and see if that works out. Otherwise I'll try to debug with a logfile as you suggested, thanks!
The script appears to be missing the #! line. Without that, it is unclear which interpreter should be used for executing the script.
- Thank you for pointing it out. I'll fix it as soon as possible and see if it solves the issue.
  
  However, the script I pasted is fired by another script (called docker_backupper.sh, that is the one triggered by the cronjob and whose purpose is firing a specific script for each service to be backed up) and that script has the #!/bin/bash on top, so I fear adding it also to the "invoked scripts" won't change that much

7 comments