Log4j Docker Support

Log4j supports Docker by providing a Lookup to retrieve container information.

Accessing Docker

The Log4j Docker support requires access to the Docker REST interface. In practical terms this means the application either needs access to unix:///var/run/docker.sock through a volume mount (not recommended), bind Docker to another host/port or unix socket. or use a proxy application to provide access. The Log4j Spring Cloud sample application uses a socat proxy to access Docker.

Lookup Attributes

Log4j Docker provides access to the following container attributes:

  • containerId - The full id assigned to the container.
  • containerName - The name assigned to the container.
  • imageId - The id assigned to the image.
  • imageName - The name assigned to the image.
  • shortContainerId - The first 12 characters of the container id.
  • shortImageId - The first 12 characters of the image id.

Attributes may be accessed by adding


to the configuration. Note that docker variables are only resolved once during logging initialization so they shouldn't be referenced with more than one ‘$’ character.


Log4j Docker requires Log4j Core, Log4j API and a minimum of Java 8. For more information, see Runtime Dependencies.