Watchtower is a Docker container update automator that monitors registries for new image pushes and automatically restarts containers with the latest versions. It functions as a container lifecycle manager, handling the process of bringing running containers up to date without manual intervention.
The service includes specialized controls to manage deployment risk and precision, such as image age deferral and deployment cooldowns to protect against buggy releases. It supports image tag pinning to restrict updates to specific version series and can operate as a self-updating service to maintain its own currency.
Beyond basic updates, the project provides infrastructure monitoring through Prometheus-compatible metrics and a webhook notification system with template-driven reporting. It manages the update lifecycle through sequential dependency-aware restarts, custom termination signals, and post-update image resource cleanup. For extended environments, it supports private registry authentication, remote daemon communication, and a token-secured management API for remote update triggers.