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Version: 1.0

manifest: the shared vocabulary

github.com/yohimik/dispat/pkg/manifest is the vocabulary shared by the manifest reader and the manifest writer. It exists so the two halves can never drift apart: both range over the same format list, spell dependency kinds the same way, and agree byte for byte on what a Docker reference is.

There is no I/O here and no dependencies. The package is models, pure functions and a few parsers, and nothing in it touches a filesystem.

go get github.com/yohimik/dispat/pkg/manifest

The surface, by concern​

Formats. Format names each of the twenty-three recognised manifest formats, Formats is the canonical list both halves prove they cover, and FormatOf maps a file name onto its format. IsRequirementsFile and IsDockerfile are the two naming rules too wordy for a lookup table: requirements files match by whole words, and Dockerfiles match Dockerfile, Dockerfile.dev, api.Dockerfile and Containerfile while excluding prose extensions.

Kinds. Kind is the dependency field a declaration came from, with four constants spelled like the fields themselves and the zero value standing for plain dependencies. ParseKind reads a spelling from a configuration file or a command line, accepting "dependencies" as the long form of the zero value.

Names. NameWords splits a file's base name into words, and NormalizePyName applies PEP 503 identically on both sides, which is what keeps Acme_Core and acme-core one package.

Docker. ParseImageRef reads an image reference into repository, tag and digest, including the tag's byte span. ValidTag is the registry tag grammar. DockerfileRefs walks a Dockerfile's FROM, COPY --from and RUN --mount instructions with stage-alias scoping. ComposeService and ComposeIdentity decide which service's image names a compose file. These parsers live here rather than in the reader or the writer precisely so both get byte-identical offsets.

In use​

manifest.FormatOf("Dockerfile.dev")                 // FormatDockerfile, true
manifest.KindDevDependencies                        // the four dependency kinds, spelled like the fields
manifest.ParseKind("dependencies")                  // KindDependencies, true
manifest.IsRequirementsFile("requirements-dev.txt") // true
manifest.NormalizePyName("Acme_Core")               // "acme-core" (PEP 503)
manifest.ParseImageRef("ghcr.io/acme/api:1.2.0")    // repository, tag and the tag's span

The byte span is the detail that makes the pair work. The reader records where a version sits, and the writer splices exactly that range, so a rewrite changes the version text and leaves everything around it untouched.

Further reading​