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Need help understanding a back-up script (self.selfhosted)

submitted 9 months ago by Natal to c/selfhosted

13 comments fedilink hide all child comments

Hello everyone!

I had a container with a DB crap itself yesterday so I'm trying to speed up my learning to back up stuff.

I came across a script that taught me how to back-up a containerized postgres db at given intervals and it works. I managed to create db dumps and restore them. I've documented everything and now my whole docker-compose/env etc are on git control.

There's one part of the script I don't decypher but I'd like to maybe change it. It is about the number of back-up copies.

Here's the line from the tutorial: ls -1 /backup/*.dump | head -n -2 | xargs rm -f

Can someone explain to me what this line does? I'd like to keep maybe 3 copies just in case the auto-backup backs up a rotten one.

Thanks!

Full code below:

backup:
    image: postgres:13
    depends_on:
      - db_recipes
    volumes:
      - ./backup:/backup
    command: >
      bash -c "while true; do
        PGPASSWORD=$$POSTGRES_PASSWORD pg_dump -h db-postgresql -U $$POSTGRES_USER -Fc $$POSTGRES_DB > /backup/$$(date +%Y-%m-%d-%H-%M-%S).dump
        echo ""Backup done at $$(date +%Y-%m-%d_%H:%M:%S)""
        ls -1 /backup/*.dump | head -n -2 | xargs rm -f
        sleep 86400
      done"

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[–] [email protected] 0 points 9 months ago

If you want to get more in depth, I've been using this container:

https://github.com/jareware/docker-volume-backup

It can be setup in the same compose or in it's own, and it supports pre/post commands if you want to dump a db or stop a container before backup.

Additionally, Setting a post backup command like in their docs:

POST_BACKUP_COMMAND: "docker run --rm -e DRY_RUN=false -e DAILY=3 -e WEEKLY=1 -e MONTHLY=1 -v /backup:/archive ghcr.io/jan-brinkmann/docker-rotate-backups"

Lets you specify the number of backups retained per period, E.G. 3 daily, 1 weekly, 1 monthly.

You could also mix and match.