Watchtower can send notifications when containers are updated. Notifications are sent via hooks in the logging system, [logrus](http://github.com/sirupsen/logrus).
The types of notifications to send are passed via the comma-separated option `--notifications` (or corresponding environment variable `WATCHTOWER_NOTIFICATIONS`), which has the following valid values:
-`email` to send notifications via e-mail
-`slack` to send notifications through a Slack webhook
-`msteams` to send notifications via MSTeams webhook
-`--notifications-level` (env. `WATCHTOWER_NOTIFICATIONS_LEVEL`): Controls the log level which is used for the notifications. If omitted, the default log level is `info`. Possible values are: `panic`, `fatal`, `error`, `warn`, `info` or `debug`.
## Available services
### Email
To receive notifications by email, the following command-line options, or their corresponding environment variables, can be set:
-`--notification-email-from` (env. `WATCHTOWER_NOTIFICATION_EMAIL_FROM`): The e-mail address from which notifications will be sent.
-`--notification-email-to` (env. `WATCHTOWER_NOTIFICATION_EMAIL_TO`): The e-mail address to which notifications will be sent.
-`--notification-email-server` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER`): The SMTP server to send e-mails through.
-`--notification-email-server-tls-skip-verify` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER_TLS_SKIP_VERIFY`): Do not verify the TLS certificate of the mail server. This should be used only for testing.
-`--notification-email-server-port` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PORT`): The port used to connect to the SMTP server to send e-mails through. Defaults to `25`.
-`--notification-email-server-user` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER_USER`): The username to authenticate with the SMTP server with.
-`--notification-email-server-password` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD`): The password to authenticate with the SMTP server with.
-`--notification-email-subjecttag` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SUBJECTTAG`): Prefix to include in the subject tag. Useful when running multiple watchtowers.
If watchtower is monitoring the same Docker daemon under which the watchtower container itself is running (i.e. if you volume-mounted _/var/run/docker.sock_ into the watchtower container) then it has the ability to update itself. If a new version of the _containrrr/watchtower_ image is pushed to the Docker Hub, your watchtower will pull down the new image and restart itself automatically.
To receive notifications in Slack, add `slack` to the `--notifications` option or the `WATCHTOWER_NOTIFICATIONS` environment variable.
Additionally, you should set the Slack webhook URL using the `--notification-slack-hook-url` option or the `WATCHTOWER_NOTIFICATION_SLACK_HOOK_URL` environment variable.
By default, watchtower will send messages under the name `watchtower`, you can customize this string through the `--notification-slack-identifier` option or the `WATCHTOWER_NOTIFICATION_SLACK_IDENTIFIER` environment variable.
Other, optional, variables include:
-`--notification-slack-channel` (env. `WATCHTOWER_NOTIFICATION_SLACK_CHANNEL`): A string which overrides the webhook's default channel. Example: #my-custom-channel.
-`--notification-slack-icon-emoji` (env. `WATCHTOWER_NOTIFICATION_SLACK_ICON_EMOJI`): An [emoji code](https://www.webpagefx.com/tools/emoji-cheat-sheet/) string to use in place of the default icon.
-`--notification-slack-icon-url` (env. `WATCHTOWER_NOTIFICATION_SLACK_ICON_URL`): An icon image URL string to use in place of the default icon.
Additionally, you should set the MSTeams webhook URL using the `--notification-msteams-hook` option or the `WATCHTOWER_NOTIFICATION_MSTEAMS_HOOK_URL` environment variable.
MSTeams notifier could send keys/values filled by `log.WithField` or `log.WithFields` as MSTeams message facts. To enable this feature add `--notification-msteams-data` flag or set `WATCHTOWER_NOTIFICATION_MSTEAMS_USE_LOG_DATA=true` environment variable.