Enable and configure the GitLab Dependency Proxy for a group to cache Docker Hub images and reduce pull rate-limit failures in CI pipelines

Steps

1. Enable the Dependency Proxy for the group in GitLab by navigating to Settings > Packages and registries > Dependency Proxy, or via the Groups API: PUT /api/v4/groups/<GROUP_ID> with dependency_proxy_enabled: true
2. In CI pipeline jobs, replace docker.io/<image>:<tag> references with <GITLAB_HOST>/<GROUP_PATH>/dependency_proxy/containers/<image>:<tag> to route pulls through the proxy
3. Authenticate CI runners against the proxy using the predefined CI_DEPENDENCY_PROXY_USER and CI_DEPENDENCY_PROXY_PASSWORD variables in the docker login step targeting CI_DEPENDENCY_PROXY_SERVER
4. Configure Docker Hub credentials on the group proxy settings to use an authenticated Docker Hub account and avoid anonymous rate limits: set the upstream credentials via Settings or the API
5. Purge stale cached images using the DELETE /api/v4/groups/<GROUP_ID>/dependency_proxy/cache endpoint to force re-pulls of updated base images