Upgrading Existing Postgres in Docker/Compose

docker pg upgrade.md

Example done from an upgrade from 12.5 to 15.4

App is a Rails app, the default container user has limited access and no direct sql/psql access

• build the image with current pg version & docker compose up
• docker exec -it <NAME_OF_CONTAINER> pg_dump <NAME_OF_PRIMARY_DB> > db.out -U postgres
  • had issues doing pg_dumpall; wondering if the default postgres database interferred?
• backup the data from the volume. I store in a tmp folder in the repo.
• clear the folder your data is saved in or delete the volume
• update the postgres version in docker compose, run docker compose build & up
• service should start and create default database if configured to do so
• copy the db.out into the database container:
  • docker ps and copy the ID of the container
  • docker cp db.out <ID>:/db.out
• Load the db from the dump file
  • docker exec -it <NAME_OF_DATABASE_CONTAINER> /bin/bash
  • ls to ensure the db.out file is present
  • psql <DATABSE_NAME> < db.out -U postgres
    • substititute postgres for the name of the db connection user as-needed