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- Better clarify images are only updated to newer image updates to the same tag of the running container(s). - Slight revisions to existing content.
2.8 KiB
2.8 KiB
| title |
|---|
| Maintenance | Update and Cleanup |
containrrr/watchtower is a service that monitors Docker images for updates, automatically applying them to running containers.
!!! example "Automatic image updates + cleanup"
Run a `watchtower` container with access to `docker.sock`, enabling the service to manage Docker:
```yaml title="compose.yaml"
services:
watchtower:
image: containrrr/watchtower:latest
# Automatic cleanup (removes older image pulls from wasting disk space):
environment:
- WATCHTOWER_CLEANUP=true
volumes:
- /var/run/docker.sock:/var/run/docker.sock
```
!!! tip "The image tag used for a container is monitored for updates (eg: :latest, :edge, :13)"
The automatic update support is **only for updates to that specific image tag**.
- Your container will not update to a new major version tag (_unless using `:latest`_).
- Omit the minor or patch portion of the semver tag to receive updates for the omitted portion (_eg: `13` will represent the latest minor + patch release of `v13`_).
!!! tip "Updating only specific containers"
By default the `watchtower` service will check every 24 hours for new image updates to pull, based on currently running containers (_**not restricted** to only those running within your `compose.yaml`_).
Images eligible for updates can configured with a [custom `command`][docker-docs-compose-command] that provides a list of container names, or via other supported options (eg: labels). This configuration is detailed in the [`watchtower` docs][watchtower-docs].
!!! info "Manual cleanup"
`watchtower` also supports running on-demand with `docker run` or `compose.yaml` via the `--run-once` option.
You can alternatively invoke cleanup of Docker storage directly with:
- [`docker image prune --all`][docker-docs-prune-image]
- [`docker system prune --all`][docker-docs-prune-system] (_also removes unused containers, networks, build cache_).
If you omit the `--all` option, this will instead only remove ["dangling" content][docker-prune-dangling] (_eg: Orphaned images_).