# Container selection - Watchtower

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# Container selection

By default, watchtower will watch all containers. However, sometimes only some containers should be updated.

There are two options:

- Fully exclude: You can choose to exclude containers entirely from being watched by watchtower.
- Monitor only: In this mode, watchtower checks for container updates, sends notifications and invokes the pre-check/post-check hooks on the containers but does not perform the update.

## Full Exclude

If you need to exclude some containers, set the com.centurylinklabs.watchtower.enable label to `false`. For clarity this should be set on the container(s) you wish to be ignored, this is not set on watchtower.

dockerfiledocker rundocker-compose

    LABEL com.centurylinklabs.watchtower.enable="false"

    docker run -d --label=com.centurylinklabs.watchtower.enable=false someimage

    version: "3"
    services:
      someimage:
        container_name: someimage
        labels:
          - "com.centurylinklabs.watchtower.enable=false"

If instead you want to only include containers with the enable label, pass the `--label-enable` flag or the `WATCHTOWER_LABEL_ENABLE` environment variable on startup for watchtower and set the com.centurylinklabs.watchtower.enable label with a value of `true` on the containers you want to watch.

dockerfiledocker rundocker-compose

    LABEL com.centurylinklabs.watchtower.enable="true"

    docker run -d --label=com.centurylinklabs.watchtower.enable=true someimage

    version: "3"
    services:
      someimage:
        container_name: someimage
        labels:
          - "com.centurylinklabs.watchtower.enable=true"

If you wish to create a monitoring scope, you will need to run multiple instances and set a scope for each of them.

Watchtower filters running containers by testing them against each configured criteria. A container is monitored if all criteria are met. For example:

- If a container's name is on the monitoring name list (not empty `--name` argument) but it is not enabled (centurylinklabs.watchtower.enable=false), it won't be monitored;
- If a container's name is not on the monitoring name list (not empty `--name` argument), even if it is enabled (centurylinklabs.watchtower.enable=true and `--label-enable` flag is set), it won't be monitored;

## Monitor Only

Individual containers can be marked to only be monitored (without being updated).

To do so, set the com.centurylinklabs.watchtower.monitor-only label to `true` on that container.

    LABEL com.centurylinklabs.watchtower.monitor-only="true"

Or, it can be specified as part of the `docker run` command line:

    docker run -d --label=com.centurylinklabs.watchtower.monitor-only=true someimage

When the label is specified on a container, watchtower treats that container exactly as if `WATCHTOWER_MONITOR_ONLY` was set, but the effect is limited to the individual container.