Backups the Docker volume, updates the Postgres version and finally restores the data in the new Postgres version

update_docker_postgres_version.sh

# Backup the data. Taken from https://stackoverflow.com/a/67568671/7058363
docker volume create --name backup_volume

docker container run --rm -it -v [old volume]:/from -v backup_volume:/to alpine ash -c "cd /from ; cp -av . /to"

# Export Postgres data
docker exec -t [name of DB container] pg_dump [db name] | gzip > exported_postgres_data.sql.gz

# MANUAL: stop the Docker container to which the volume is attached...

# Remove the old volume to prevent issues starting Postgres service (with the new version) on the same volume
docker volume rm [old volume]

# If needed, create the empty volume again
docker volume create --name="[old volume]"

# MANUAL: now you can update Posgres version in docker-compose.yml file or K8S service...

# Import data
zcat exported_postgres_data.sql.gz | docker exec -i [name of DB container] psql [db name]

# If everything went well, remove the backup volume and the exported file
docker volume rm backup_volume

rm ./exported_postgres_data.sql.gz