🍴 Fork Notice: This is an actively maintained fork of containrrr/watchtower by @X4Applegate.

The upstream project is no longer maintained. This fork applies bug fixes and dependency updates. See CHANGELOG.md for details.

Watchtower

A process for automating Docker container base image updates.

Quick Start

With watchtower you can update the running version of your containerized app simply by pushing a new image to the Docker Hub or your own image registry. Watchtower will pull down your new image, gracefully shut down your existing container and restart it with the same options that were used when it was deployed initially.

Run the watchtower container with the following command:

$ docker run --detach \
  --name watchtower \
  --volume /var/run/docker.sock:/var/run/docker.sock \
  containrrr/watchtower

Watchtower is intended to be used in homelabs, media centers, local dev environments, and similar. We do not recommend using Watchtower in a commercial or production environment. If that is you, you should be looking into using Kubernetes. If that feels like too big a step for you, please look into solutions like MicroK8s and k3s that take away a lot of the toil of running a Kubernetes cluster.

Running with Docker Compose

This fork ships a ready-to-use docker-compose.yml that pulls the pre-built image from GHCR and loads configuration from a .env file.

# 1. Copy the example env file and edit it
cp example.env .env

# 2. Edit .env with your preferred settings
nano .env   # or vim, code, etc.

# 3. Start Watchtower
docker compose up -d

Environment Variables (.env)

Watchtower is configured entirely through environment variables. An example.env file is provided in this repository as a reference — copy it to .env and adjust the values to suit your setup.

Variable	Default	Description
WATCHTOWER_POLL_INTERVAL	86400	How often (in seconds) to check for image updates. Default is 24 h.
WATCHTOWER_SCHEDULE	(unset)	Cron expression for update checks (overrides POLL_INTERVAL when set). Example: 0 0 * * * * (every hour).
WATCHTOWER_HTTP_API_METRICS	false	Expose a Prometheus metrics endpoint on port 8080.
WATCHTOWER_HTTP_API_UPDATE	false	Enable the HTTP API trigger endpoint (allows triggering an update via HTTP).
WATCHTOWER_HTTP_API_TOKEN	(required if API enabled)	Bearer token to protect the HTTP API. Change this value.
WATCHTOWER_CLEANUP	false	Remove old images automatically after a container is updated.
WATCHTOWER_LOG_LEVEL	info	Logging verbosity. One of: panic, fatal, error, warn, info, debug, trace.
WATCHTOWER_NOTIFICATIONS	(unset)	Notification provider(s). Supported: email, slack, msteams, gotify, shoutrrr.
WATCHTOWER_LABEL_ENABLE	false	When true, only containers with the label com.centurylinklabs.watchtower.enable=true are monitored.
WATCHTOWER_RUN_ONCE	false	Check for updates once and exit immediately (useful when triggered by an external scheduler).

Tip: Notification-specific variables (e.g. email server, Slack webhook URL) are documented in the example.env file and in the full documentation.

Documentation

The full documentation is available at https://containrrr.dev/watchtower.

Changelog

See CHANGELOG.md for the full change history of this fork.

Recent changes in this fork:

• docker-compose.yml — simplified to use the published GHCR image (ghcr.io/x4applegate/watchtower:latest) and load config via env_file: .env.
• example.env — added as a reference configuration template covering polling, HTTP API, notifications, and behaviour flags.