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Configuration
Logging and Output

Logging and Output

Debug

Enables debug mode with verbose logging.

            Argument: --debug, -d
Environment Variable: WATCHTOWER_DEBUG
                Type: Boolean
             Default: false

Equivalent to --log-level debug. As an argument, it does not accept a value (e.g., --debug true is invalid).

See Maximum Log Level.

Trace

Enables trace mode with highly verbose logging, including sensitive information like credentials.

            Argument: --trace
Environment Variable: WATCHTOWER_TRACE
                Type: Boolean
             Default: false

Equivalent to --log-level trace. As an argument, does not accept a value (e.g., --trace true is invalid).

See Maximum Log Level.

Use with caution due to credential exposure.

Maximum Log Level

Sets the maximum log level output to STDERR, visible in docker logs when running Watchtower in a container.

            Argument: --log-level
Environment Variable: WATCHTOWER_LOG_LEVEL
     Possible Values: panic, fatal, error, warn, info, debug, trace
             Default: info

Logging Format

Specifies the format for console log output.

            Argument: --log-format, -l
Environment Variable: WATCHTOWER_LOG_FORMAT
     Possible Values: Auto, LogFmt, Pretty, JSON
             Default: Auto

Disable ANSI Colors

Disables ANSI color escape codes in log output for plain text logs.

            Argument: --no-color
Environment Variable: NO_COLOR
                Type: Boolean
             Default: false

Programmatic Output (Porcelain)

Outputs session results in a machine-readable format.

            Argument: --porcelain, -P
Environment Variable: WATCHTOWER_PORCELAIN
     Possible Values: v1, json
             Default: None

Equivalent to:

--notification-url logger://
--notification-log-stdout
--notification-report

For v1, the template is porcelain.v1.summary-no-log, producing one container per line.

For json, the template is porcelain.json, producing a JSON document:

{
  "containers": [
    {
      "name": "nginx",
      "image": "nginx:latest",
      "image_id": "abc123",
      "latest_image_id": "def456",
      "state": "Updated",
      "update_available": true
    }
  ]
}

Fields:

  • name — container name
  • image — image name with tag
  • image_id — current short image ID
  • latest_image_id — latest short image ID
  • state — container state (Updated, Fresh, Failed, Skipped, Restarted, Stale)
  • update_available — whether an update is available
  • error — error message if any (omitted when empty)
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