====== Duplicate uploads issue ======

Scenario:
  - build ''project'' Docker image with tags ''project:latest'' and ''project:my_feature''
  - push all tags of ''project'' with commands ''docker push -s project''
  - 1st tag ''latest'' is pushed
    - preparation of layers (compression, etc)
    - pushing layers
  - 2dn tag ''my_feature'' is pushed
    - preparation of layers (compression, etc)
    - pushing layers
    - server responds ''layer already exists''

So duplicate layers are not stored server side, but still all of them are compressed and pushed which take long time.

  * [[https://gitlab.com/gitlab-org/gitlab/-/issues/15237]]
  * 
  * [[https://gitlab.com/gitlab-org/gitlab/-/issues/23132]]


Solution:
  * use Buildkit's external cache [[https://docs.docker.com/build/cache/backends/|Cache storage backends]]

====== Gilab's registry ======

/opt/gitlab/embedded/bin/registry

<code bash>
./registry --version
./registry github.com/docker/distribution v3.76.0-gitlab
</code>

Config file: ''/var/opt/gitlab/registry/config.yml''

During ''docker push'' registry store received layers in: ''/var/opt/gitlab/gitlab-rails/shared/registry/docker/registry/v2/repositories/GROUP/PROJECTs/_uploads/4786e5fa-4e9b-4342-9c6f-3c80d72d07db/data''