# Running multiple instances - Watchtower

# Running multiple instances

By default, Watchtower will clean up other instances and won't allow multiple instances running on the same Docker host or swarm. It is possible to override this behavior by defining a scope to each running instance.

Note

- Multiple instances can't run with the same scope;
- An instance without a scope will clean up other running instances, even if they have a defined scope;
- Supplying `none` as the scope will treat `com.centurylinklabs.watchtower.scope=none`, `com.centurylinklabs.watchtower.scope=` and the lack of a `com.centurylinklabs.watchtower.scope` label as the scope `none`. This effectly enables you to run both scoped and unscoped watchtower instances on the same machine.

To define an instance monitoring scope, use the `--scope` argument or the `WATCHTOWER_SCOPE` environment variable on startup and set the `com.centurylinklabs.watchtower.scope` label with the same value for the containers you want to include in this instance's scope (including the instance itself).

For example, in a Docker Compose config file:

    version: '3'

    services:
      app-with-scope:
        image: myapps/monitored-by-watchtower
        labels: [ "com.centurylinklabs.watchtower.scope=myscope" ]

      scoped-watchtower:
        image: containrrr/watchtower
        volumes: [ "/var/run/docker.sock:/var/run/docker.sock" ]
        command: --interval 30 --scope myscope
        labels: [ "com.centurylinklabs.watchtower.scope=myscope" ]

      unscoped-app-a:
        image: myapps/app-a

      unscoped-app-b:
        image: myapps/app-b
        labels: [ "com.centurylinklabs.watchtower.scope=none" ]

      unscoped-app-c:
        image: myapps/app-b
        labels: [ "com.centurylinklabs.watchtower.scope=" ]

      unscoped-watchtower:
        image: containrrr/watchtower
        volumes: [ "/var/run/docker.sock:/var/run/docker.sock" ]
        command: --interval 30 --scope none