README.md

genspec

Point it at annotated Go source, get a Swagger 2.0 document.

go install github.com/go-openapi/codescan/cmd/genspec@latest

# scan the module in the current directory, write the document to standard output
genspec

# somewhere else, narrowed, to a file, and checked
genspec -workdir ../my-api -output swagger.yaml -validate ./internal/api/...

This is the ordinary native command. Everything the library can be told is a flag, the document goes to standard output or to -output, and what the scan observed goes to standard error as colored diagnostics.

NOTE genspec is a standalone CLI that works like go-swagger "swagger generate spec" command, but is released independently and will benefit fixes and enhancements at a faster pace than go-swagger releases. go-swagger has a larger scope and more dependencies.

Which one to reach for

Three commands run the same scan. The question is about the machine, not about the specification:

Command	Use it when
genspec	you are on a normal machine and want a specification
genspec-wasi	there is no Go toolchain, no subprocess, or you are running under WebAssembly — it takes no dependency beyond the library. It also speaks a machine-readable envelope (-format=json) carrying diagnostics and cross-references
genspec-tui	you are working on the annotations and want the source and the document side by side, live

They share their flag surface: internal/cliopts declares every knob the library takes, once, so -name-from-tags means the same thing whichever one you reach for. A guard there fails the build when an option lands with no flag.

Configuration file

Anything that can be a flag can be preset in a .codescan.yaml, found by searching upwards from wherever you are — so a project configures itself once and the command is run bare:

scan:
  workdir: ./api
  exclude-tags: [internal]

emit:
  scan-models: true
  name-from-tags: [form, json]

document:
  format: yaml
  output: swagger.yaml

diagnostics:
  validate: true
  fail-on: warning

Keys are grouped into sections, and inside a section a key is the flag it sets, spelled exactly as on the command line — so genspec -h doubles as the reference for the file. The sections are the families below, plus document and diagnostics for this command's own flags.

Anything typed wins. That holds for a flag typed with the value it already had: -scan-models=false means false even where the file says true.

-config <path> — or -c <path> — reads a particular file, which must exist. --no-config reads none, whatever is lying around, for a run that has to be reproducible. Asking for both at once is an error rather than a coin toss. .codescan.yml and .codescan.json are searched for too — JSON is a subset of YAML, so it needs no parser of its own.

One file serves the whole family: a section a command does not know is skipped rather than refused, so genspec-tui's settings can sit beside genspec's. A key inside a section it does know must name one of its flags — which is what makes a typo an error rather than a setting that quietly never applied. Run with -verbose to see which file was read and which keys it skipped.

Output

-output names the file, or - for standard output (the default). -format is json, yaml, or auto — which reads the extension of -output and writes JSON when that says nothing. So the common cases need no -format at all:

genspec -output swagger.yaml     # YAML, because of the name
genspec -output swagger.json     # JSON
genspec > swagger.json           # JSON
genspec -compact                 # JSON with no indentation

YAML is derived from the JSON rendering, which costs key order: the document comes out alphabetical rather than in the order the spec types declare. Same information, different diff against a hand-written file.

-input merges the scan's discoveries into an existing document — the place for everything a scanner cannot know, such as the host, the security definitions, or a hand-written path the annotations do not describe.

Diagnostics

Everything the scan observed is reported on standard error, colored when that is a terminal. Nothing is written there when there is nothing to say.

Flag	Meaning
-quiet	say nothing at all
-verbose	also report hints, which are muted by default
-color	auto (a terminal), always, never. auto honours NO_COLOR and TERM=dumb
-validate	check the document against the Swagger 2.0 schema and report what is wrong with it
-fail-on	exit non-zero when something reaches this severity: error, warning, or never

-fail-on covers what -validate found as well as what the scan observed: they reach the reader as one stream, so a threshold that saw only half of it would be a trap rather than a policy. It defaults to never, because a scan that emits warnings is the ordinary case, and a command that failed the build over one would mostly teach people to stop reading them.

Exit status

A specification is written whenever one could be produced, so a non-zero status describes what was wrong with it rather than meaning nothing came out.

Status	Meaning
0	the scan produced a document, and nothing asked for more
1	the scan failed
2	the command line does not make sense
3	what was reported reached the severity -fail-on names
4	-validate found the document invalid

-validate finding the document invalid outranks -fail-on: it is the more specific answer.

Scan options

genspec -h lists them all. They fall into families:

• what to scan — -workdir, the positional package patterns, -build-tags, -include / -exclude, -include-tags / -exclude-tags, -exclude-deps
• what to build it as — -goos, -goarch, -goflags, -gowork, -goexperiment. Each changes what gets compiled, and so what the document says; each is a flag rather than inherited state, so a scan is reproducible
• how to load it — -loader, -stub-stdlib, -skip-compiled-dependencies
• what to emit — -scan-models, -prune-unused-models, the alias and allOf knobs, -skip-extensions, the naming knobs, the doc-comment knobs

They are the library's own options under their own names: a flag is the kebab-case of the field it writes, without exception. See the package documentation for what each one means.