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Automatic container updates with Podman quadlets

·438 words·3 mins·
containers podman fedora linux quadlet systemd
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Running containers at home or in production often means juggling updates across multiple services. While orchestration platforms like Kubernetes handle this automatically, what about those simple deployments on a single host?

Podman’s quadlet system integrates containers directly with systemd, and when combined with automatic updates, you get a robust solution that keeps your containers fresh without manual intervention.

Let’s explore how to set up automatic container updates using Podman quadlets on Fedora, turning container management into a hands-off operation that just works.

Setting up a basic quadlet #

First, let’s create a simple quadlet for running a Valkey database service under a user account. Quadlet files for user services live in ~/.config/containers/systemd/.

Create the directory if it doesn’t exist:

mkdir -p ~/.config/containers/systemd/

Then create your quadlet file:

# ~/.config/containers/systemd/valkey.container
[Container]
ContainerName=valkey
Image=docker.io/valkey/valkey:latest
Label=io.containers.autoupdate=registry
PublishPort=16379:6379
Volume=valkey_data:/data

[Service]
Restart=always

[Install]
WantedBy=default.target

The magic happens with the Label=io.containers.autoupdate=registry line. This label tells Podman that this container should be automatically updated when a newer image is available in the registry.

After creating the file, reload systemd and start your container:

systemctl --user daemon-reload
systemctl --user start valkey.service

Your container is now running as a user systemd service! Check its status with:

systemctl --user status valkey.service
podman ps

Enabling automatic updates #

Podman ships with a systemd timer that checks for container updates. The podman-auto-update.timer runs daily by default, but you need to enable it for your user:

systemctl --user enable --now podman-auto-update.timer

You can check when the next update will run:

systemctl --user list-timers podman-auto-update.timer

When the timer triggers, it runs podman auto-update, which:

  1. Checks all containers with the io.containers.autoupdate label
  2. Pulls newer images if available
  3. Restarts containers with the new image
  4. Keeps the old image in case you need to roll back

Customizing update behavior #

The io.containers.autoupdate label supports different values for various update strategies:

# Always pull the latest image from the registry
Label=io.containers.autoupdate=registry

# Only update if the local image changes (useful for locally built images)
Label=io.containers.autoupdate=local

You can also customize when updates occur by creating a timer override:

systemctl --user edit podman-auto-update.timer

Add these lines to run updates every 6 hours instead of daily:

[Timer]
OnCalendar=
OnCalendar=*-*-* 00,06,12,18:00:00

Monitoring updates #

Track what’s happening with your automatic updates using journalctl:

# View recent auto-update logs
journalctl --user -u podman-auto-update.service -n 50

# Follow updates in real-time
journalctl --user -u podman-auto-update.service -f

# Check a specific container's restart history
journalctl --user -u valkey.service | grep Started

Further reading #