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.
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.