ADR 0075: The daemonless build of ADR 0073 ships in 0.5.4, and pushed images are read back through the registry

Status: Accepted Date: 2026-10-13 Relates: ADR 0073 (daemonless image builds), ADR 0068 (patch content gated by safety), ADR 0041 (deploy and digest pinning), ADR 0015 (no Docker SDK) Issues: #1706

Context

ADR 0073 decided how a DAG image is built without a container daemon and scoped 0.5.4 to the builder seam, the builder line and --platform (its section 6). It left the registry client, the image split, the daemonless dependency layer and the remote builder to v0.6.

The maintainers then decided that the whole of #1706 ships in 0.5.4. A Pro deploy that needs Docker is the main friction the build and deploy review found, and waiting for a minor that has no date leaves it in place.

Section 5 of ADR 0073 also checks a multi-platform push with <tool> manifest inspect, and the digest comes from <tool> inspect. Both read state the local tool keeps, which a build that ran elsewhere does not have.

Decision

1. Scope. Section 6 of ADR 0073 is replaced: 0.5.4 ships, in this order, the registry client, the skip path, the image split with the code layer, the daemonless dependency layer, and the remote builder in the chart. Each lands behind the builder seam as its own pull request, with its own review, and changes no caller. Each must meet the safety bar of ADR 0068 on its own; one that does not moves to the next patch, and the paths before it still ship.

2. The registry is the source of the digest. Once the registry client exists, every builder, including the local daemon, reads the digest of the image it pushed from the registry, through the client and credentials of ADR 0073 section 3. deploy --skip-build does the same, so an image pushed by any tool (Cloud Build, kaniko, a CI job) can be deployed without a local copy. <tool> inspect is no longer called.

   Note (2026-10, #1885). The local daemon now takes the digest from the tool’s report of its own push (the buildx metadata file, podman’s --digestfile, the last line of docker push) and reads the registry at that digest only to check a multi-platform push; the tag read remains for a tool that reports none. See ADR 0087.

3. The platform check reads the registry too. The multi-platform check of ADR 0073 section 5 reads the pushed manifest through the registry client instead of <tool> manifest inspect. What it checks is unchanged: the digest must name an index that holds every requested platform, and anything it cannot confirm fails the build before anything is registered.

4. The pinned reference keeps the user’s spelling. The reference registered is the image as written in the project, with its tag replaced by the digest the registry returned (reg.io/team/etl@sha256:...), not a normalized form, so docker.io images read the same as they did through inspect.

Consequences

• A deploy needs read access to the registry it pushes to, with the credentials docker login or a credential helper wrote to ~/.docker/config.json. For docker that is the access the push used. podman keeps its own auth.json, which the client reads only when no docker config exists, so a podman user with both logs in with docker login too.
• Plain HTTP is allowed only to localhost, *.localhost and loopback addresses. go-containerregistry would also use it for private (RFC 1918) addresses, falling back from HTTPS to whichever scheme answers first, which would hand the credentials and the choice of digest to anyone answering HTTP on the network; the client refuses that.
• The digest is what the tag names when it is read, right after the push. Two pushes of the same tag at the same moment (two jobs building one version) can make one deploy register the other’s image. The default tag is the content version or the git commit, so the two images usually come from the same sources; a tag reused across different sources (uncommitted changes, a version label that was not bumped) is the case to avoid. Comparing with the digest the tool reports on push is left to the daemonless builders, which push in process and know it.
• The local tool only builds and pushes. podman and nerdctl no longer need an inspect that matches docker’s output format.
• The new dependency (go-containerregistry) arrives in a patch. It is linked by the CLI only, enforced by internal/build/deps_test.go and a depguard rule, and gated by make vuln like every module (ADR 0014).
• The rc of 0.5.4 waits for the paths that meet the bar.