The gitlab docker registry has no cleanup job per default. If an image tag gets overwritten (updated) then the original image layer blobs will be kept as orphans. To clean those up run:
gitlab-ctl registry-garbage-collect --delete-untagged --delete-manifest
Automation
- run the command via Cron (the gitlab image contains
go-crond) - set command in env var
GITLAB_POST_RECONFIGURE_SCRIPT(executed at least on each container start)
Conclusion
170GiB server disk storage freed
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