Push slim image by digest via regctl#32
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richturner merged 1 commit intomainfrom May 7, 2026
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Replace the buildx-passthrough push (which can't push docker-daemon images by digest) with `docker save` -> `regctl image import` -> `regctl image copy` to a digest URL, leaving no per-arch tag in the registry. regctl is installed via the upstream `regclient/actions/regctl-installer` action, with `sigstore/cosign-installer` first so the binary's sigstore signature is verified. The push step retries transiently failing copies, asserts the registry credential persisted post-login, and cleans up the staged tar/OCI layout via `trap`. `Dockerfile.passthrough` existed only as the buildx workaround and is removed.
richturner
approved these changes
May 7, 2026
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Summary
docker save→regctl image import→regctl image copy <repo>@<digest>flow, so the slim image still lands in the registry without ever creating a per-arch tag.regctlis installed via the upstreamregclient/actions/regctl-installeraction, pinned tov0.11.3.sigstore/cosign-installerruns first so the action's opportunisticcosign verify-blobagainst the regclient sigstore signature actually fires (the action silently skips verification if cosign isn't onPATH).regctl image copy3× with backoff on transient registry errors, assert thatregctl registry loginpersisted the credential before staging the tar, andtrapthe tar + OCI layout cleanup so a mid-step failure doesn't leave hundreds of MB on the runner for a re-run to ENOSPC on.Dockerfile.passthrough. Its only purpose was the buildx workaround; nothing else in the repo references it.PR CI doesn't exercise the slim push (gated on non-PR events); first real run is post-merge on
main. Rollback is a single-commit revert of the merge commit.