go.mod

module m

go 1.15

require (
	github.com/go-chi/chi v4.1.2+incompatible // indirect
	github.com/podhmo/reflect-openapi v0.0.3 // indirect
)

go.sum

github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/getkin/kin-openapi v0.22.1 h1:ODA1olTp175o//NfHko/uCAAhwUSfm5P4+K52XvTg4w=
github.com/getkin/kin-openapi v0.22.1/go.mod h1:WGRs2ZMM1Q8LR1QBEwUxC6RJEfaBcD0s+pcEVXFuAjw=
github.com/ghodss/yaml v1.0.0 h1:wQHKEahhL6wmXdzwWG11gIVCkOv05bNOh+Rxn0yngAk=
github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
github.com/go-chi/chi v1.0.0 h1:s/kv1cTXfivYjdKJdyUzNGyAWZ/2t7duW1gKn5ivu+c=
github.com/go-chi/chi v4.1.2+incompatible h1:fGFk2Gmi/YKXk0OmGfBh0WgmN3XB8lVnEyNz34tQRec=
github.com/go-chi/chi v4.1.2+incompatible/go.mod h1:eB3wogJHnLi3x/kFX2A+IbTBlXxmMeXJVKy9tTv1XzQ=
github.com/nsf/jsondiff v0.0.0-20200515183724-f29ed568f4ce/go.mod h1:uFMI8w+ref4v2r9jz+c9i1IfIttS/OkmLfrk1jne5hs=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/podhmo/reflect-openapi v0.0.3 h1:s9vZGRivsHTO10L1J7GV/ezleLlSixVETJDl2vx9W34=
github.com/podhmo/reflect-openapi v0.0.3/go.mod h1:oTr6vMRd2eZVbdPxkr85wu90k6nBegq10WRy2IQzG+Y=
github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

main.go

package main

import (
	"context"
	"encoding/json"
	"log"
	"net/http"
	"os"
	"strconv"

	"github.com/go-chi/chi"
	"github.com/go-chi/chi/middleware"
	reflectopenapi "github.com/podhmo/reflect-openapi"
)

type Setup struct {
	Router  chi.Router
	Manager *reflectopenapi.Manager
}

func (s *Setup) AddEndpoint(method, path string, interactor interface{}, handle http.HandlerFunc) {
	s.Router.Method(method, path, handle)
	op := s.Manager.Visitor.VisitFunc(interactor)
	s.Manager.Doc.AddOperation(path, method, op)
}

func (s *Setup) SetupRoutes() {
	s.AddEndpoint(
		"GET", "/",
		func() string { return "" }, // この関数からpathを導出
		func(w http.ResponseWriter, r *http.Request) {
			w.Write([]byte("welcome"))
		},
	)
}

func main() {
	r := chi.NewRouter()
	r.Use(middleware.Logger)
	c := reflectopenapi.Config{}

	doc, err := c.BuildDoc(context.Background(), func(m *reflectopenapi.Manager) {
		s := &Setup{Manager: m, Router: r}
		s.SetupRoutes()
	})
	if err != nil {
		log.Fatal(err)
	}
	if ok, _ := strconv.ParseBool(os.Getenv("DOCGEN")); ok {
		enc := json.NewEncoder(os.Stdout)
		enc.SetIndent("", "  ")
		enc.Encode(doc)
		return
	}

	http.ListenAndServe(":3000", r)
}

openapi.json

{
  "components": {},
  "info": {
    "description": "-",
    "title": "Sample API",
    "version": "0.0.0"
  },
  "openapi": "3.0.0",
  "paths": {
    "/": {
      "get": {
        "operationId": "main.(*Setup).SetupRoutes.func1",
        "responses": {
          "200": {
            "content": {
              "application/json": {
                "schema": {
                  "type": "string"
                }
              }
            },
            "description": ""
          },
          "default": {
            "description": ""
          }
        }
      }
    }
  },
  "servers": [
    {
      "url": "http://localhost:8888",
      "description": "local development server"
    }
  ]
}