Conditions on cron jobs?

Is there a way to determine if the currently running build was invoked by a cron job? The reason I am asking is that daily I perform the release pipeline, but in the release pipeline I don’t only build and pack the binary, but also publish it to the dockerhub, but I don’t want to publish a nightly image there. Or, I want to distinguish between them and so in nightly jobs I’d push to dockerhub/user/image:nightly and dockerhub/user/image:<branch_name> for the usual push-to-branch builds.

Maybe we could use some pipeline environment variable, or a pipeline condition, anything?