When you run a Docker container based on a public image (say, the official postgres image), the running container doesn’t update itself when the upstream image changes. To get the update, you have to:

  1. Pull the new image from Docker Hub
  2. Stop and remove the running container
  3. Start a new container from the updated image

For a handful of personal containers, this is manageable. For a homelab with a dozen services, it gets tedious.

Watchtower Link to heading

Watchtower is a Docker container that watches your other containers and automatically handles this process for you. It periodically checks Docker Hub for newer versions of the base images your containers are using, pulls any updates it finds, and restarts the affected containers with the new image.

Setup is straightforward: follow the instructions in the Watchtower README to start the container, and it runs in the background from there.

Trade-offs Link to heading

Watchtower is convenient, but it comes with real trade-offs:

  • Uncontrolled updates: A new image version could introduce breaking changes. Your container restarts with the update before you’ve had a chance to review it.
  • Restarts during live operations: If a container is in the middle of a transaction or serving active connections, a Watchtower-triggered restart could interrupt it.
  • Security surface: Watchtower pulls images from Docker Hub automatically, which means it acts on whatever appears there, including images that may have been compromised.

For personal projects and homelab use, especially containers running stateless or low-stakes services: Watchtower’s convenience outweighs these risks. For production or business-critical workloads, it doesn’t belong in your stack; use a proper deployment pipeline with image pinning, review, and controlled rollouts.

Updated 2026: The original Watchtower repository (v2tec/watchtower) was abandoned. The actively maintained fork is at containrrr/watchtower. If you’re running the old version, switch to the fork.