podman-quadlet-cookbook/postgresql

Podman Quadlet: PostgreSQL

Overview

PostgreSQL is started as a Podman Quadlet and before that, the database is initialized:

• either from a previous backup,
• or from scratch using SQL statements or scripts.

The upgrade process between major versions is handled by a one-off job before the database server startup.

Finally, a Podman Quadlet is provided to perform a backup of the database, including a simple retention policy.

Usage

In a separate terminal, follow the logs.

sudo make tail-logs

Install the Podman Quadlets and start PostgreSQL.

sudo make clean install

You should see the postgresql-set-major.service starting up to set the symlink pointing to the PGDATA directory of the desired major version. Then, the postgresql-init.service should start up and initialize the database from scratch. Finally, the postgresql-server.service is started.

Restart the postgresql.target unit.

sudo systemctl restart postgresql.target

You should see in the logs that the postgresql-init.service is skipped (because the database is already initialized) and the postgresql-server.service unit is started.

Increment the PostgreSQL major version number.

awk -i inplace -F= '/PG_MAJOR=/ { $2=$2+1; print $1"="$2; next } 1' /etc/quadlets/postgresql/config.env

Restart the postgresql.target unit.

sudo systemctl restart postgresql.target

In the logs, you should see that the postgresql-upgrade.service converts the database files to the new major version.

Make backups of the database.

for i in $(seq 1 10); do
    sudo systemctl start postgresql-backup.service
    sleep 1
done

In the logs, you should see ten runs of the postgresql-backup.service unit. And in the three last runs, the retention policy should be kicked in to clean up old backup files.

Now, stop the database server.

sudo systemctl stop postgresql.target

Remove all the PostgreSQL files (except the backups).

sudo find /var/lib/quadlets/postgresql/ -maxdepth 1 -mindepth 1 \! -name backup -exec rm -rf '{}' \;

Confirm there is no more data in /var/lib/quadlets/postgresql.

$ sudo ls -l /var/lib/quadlets/postgresql
total 0
drwx------. 1 avahi avahi 38  1 déc.  21:04 backup

Start the PostgreSQL database server.

sudo systemctl start postgresql.target

In the logs, you should see the postgresql-init.service unit restoring the database from the last backup.

Finally, remove the quadlets, their configuration and their data.

sudo make uninstall clean