Which Docker images does Nomad's image garbage collection remove?


I’ve got a small homelab Nomad cluster with three worker nodes. I recently ran out of disk space on one of my nodes and saw that there were a lot of old images laying around on the node. At first I thought that the Docker image GC was not working at all, but what I see mostly are previous versions of the Docker images for my jobs.

So is it possible that the GC only cleans up the most recently used image for a task which is no longer running, but leaves older image versions untouched?

So for example, I’ve got a Grafana job using the official Docker image, and I see that the three previous versions of the image are still there.

I’d check the logs (set to DEBUG or whatever) to see whether GC ran and what was the outcome.

GC settings can be customized, there’s half a dozen of them