migrate-podman-containerfile

Migrate Podman Containerfile

Convert one Podman-oriented build file into the canonical Dockerfile expected by Discovery catalog tools. Ordinary Containerfiles use Dockerfile syntax, so a plain file is normally a rename. Podman's .in preprocessing and multi-file build behavior are not safe filename-only conversions.

Input

Accept exactly one repository-relative source path under agents/ or starter-kits/. Prefer a path supplied after the slash command:

/migrate-podman-containerfile agents/example/tools/example/Containerfile

If no path is supplied, enumerate changed files in those roots and compare basenames case-insensitively. Include Containerfile, names beginning with Containerfile., ending with .Containerfile, or containing .Containerfile.; also include the corresponding Dockerfile variants when they end in .in. Continue only when exactly one candidate exists; otherwise list the candidates and stop without changing files.

Safety gates

Before writing anything:

1. Resolve the repository root with git rev-parse --show-toplevel and ensure the source remains inside agents/ or starter-kits/.
2. Set the destination to Dockerfile in the source directory.
3. Stop if the destination already exists. Never overwrite or merge it automatically.
4. Stop if the source name ends in .in, contains C-preprocessor directives such as #include, #define, or #if, or depends on included fragments.
5. Search the containing catalog item for references to the source name, repeated podman build -f/--file options, generated Containerfiles, or Podman-specific build/runtime flags. A single literal -f Containerfile reference is mechanical; variables, generated paths, multiple build files, or unclear semantics are not.
6. Inspect Dockerfile instructions. Standard instructions are ADD, ARG, CMD, COPY, ENTRYPOINT, ENV, EXPOSE, FROM, HEALTHCHECK, LABEL, MAINTAINER, ONBUILD, RUN, SHELL, STOPSIGNAL, USER, VOLUME, and WORKDIR. Stop on unknown instructions or a non-Docker syntax frontend.
7. Identify the effective build-context directory; stop if it cannot be determined or contains .containerignore. Docker does not read that file. Require manual migration of its exclusions to Docker's effective ignore file, resolving any existing .dockerignore or Dockerfile-specific ignore file, before retrying.

When a safety gate fails, make no changes. Explain the exact blocker and point to docs/authoring-guides/podman-to-docker-migration.md, including the manual steps relevant to that blocker. Do not produce a best-effort Dockerfile.

Safe migration

When every safety gate passes:

1. Rename the source to the adjacent canonical destination with git mv <source> <directory>/Dockerfile.

2. Update only exact, literal references to the old filename within the same catalog item. Replace them with Dockerfile. If a reference requires shell evaluation or changes build semantics, undo no user work; stop and report that manual migration is required.

3. Preserve file bytes, line endings, instruction order, comments, and parser directives. Do not opportunistically rewrite package commands or base images.

4. Confirm no Podman build filename remains in the migrated tool directory and inspect git diff -- <catalog-item>.

5. If Docker with Buildx is available, run a syntax-only check:

   docker buildx build --check --file Dockerfile .
   

   Run it from the tool directory. Do not run a full image build unless the user explicitly asks. If Docker/Buildx is unavailable, report the check as not run rather than treating that as success.

6. Run the repository's focused POL-022 test or PR validator when available.

Result

Report:

• source and destination paths;
• whether the conversion was a byte-preserving rename;
• any exact references updated;
• Docker syntax-check command and result, or why it was not run;
• remaining manual validation, if any.

Success requires a tracked Dockerfile and no obsolete Containerfile in the migrated tool directory.