I'm mostly documenting this so I can stop looking in the source....
Logback logging can be set at run-time via environment variables. This is primary useful in docker-compose files to enable logging in a given instance. The env variables override any other logging set by the logback.properties file included on the classpath.
At startup, the
logback.groovy file will look for any environment variables that start with
LOGBACK_ . The value of the variables must be:
level is omitted it defaults to DEBUG.
For example, in a docker-compose.override.yml file: