interactor.go

package main

type Todo struct {
	Title string `json:"title"`
	Done  bool   `json:"done"`
}

type Interactor struct {
	Store []Todo
}

func (ir *Interactor) List() ([]Todo, error) {
	return ir.Store, nil
}

func (ir *Interactor) Add(todo Todo) (Todo, error) {
	ir.Store = append(ir.Store, todo)
	return todo, nil
}

var (
	store = []Todo{
		{Title: "hello"},
		{Title: "bye bye"},
	}
)

func GetInteractor() *Interactor{
	return &Interactor{Store: store}
}

main.go

// +build !lambda

package main

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

	"github.com/go-chi/chi"
	"github.com/go-chi/render"
)

type Controller struct {
	Interactor *Interactor
}

func (c *Controller) List(w http.ResponseWriter, r *http.Request) {
	items, err := c.Interactor.List()
	if err != nil {
		render.Status(r, 500)
		render.JSON(w, r, map[string]interface{}{"message": err.Error()})
		return
	}
	render.JSON(w, r, map[string]interface{}{"items": items})
}

func (c *Controller) Add(w http.ResponseWriter, r *http.Request) {
	var item Todo
	decoder := json.NewDecoder(r.Body)
	if err := decoder.Decode(&item); err != nil {
		render.Status(r, 400)
		render.JSON(w, r, map[string]interface{}{"message": err.Error()})
	}

	added, err := c.Interactor.Add(item)
	if err != nil {
		render.Status(r, 500)
		render.JSON(w, r, map[string]interface{}{"message": err.Error()})
		return
	}
	render.JSON(w, r, added)
}

func main() {
	r := chi.NewRouter()

	// このままが良いのか、interactorの粒度を細かくしたほうが良いのかはわからない
	// github.com/awslabs/aws-lambda-go-api-proxy を使うよりは意義があるのではないか？
	// Controllerが肥大化するならたぶん分けたほうが良い。Interactorも同様ならhandler関数を生成する関数を定義する形のほうが綺麗かもしれない

	c := &Controller{Interactor: GetInteractor()}
	r.Get("/", c.List)
	r.Post("/", c.Add)

	addr := os.Getenv("ADDR")
	if addr == "" {
		addr = ":44444"
	}

	if err := http.ListenAndServe(addr, r); err != nil {
		log.Fatalf("!!%+v", err)
	}
}

main_lambda_add.go

// +build lambda
// +build add

package main

import (
	"github.com/aws/aws-lambda-go/lambda"
)

func main() {
	ir := GetInteractor()
	lambda.Start(ir.Add) // buggy
}

main_lambda_list.go

// +build lambda
// +build list

package main

import (
	"github.com/aws/aws-lambda-go/lambda"
)

func main() {
	ir := GetInteractor()
	lambda.Start(ir.List)
}

Makefile

TARGETS := $(shell cat Makefile | grep '^a\.out' | cut -d : -f 1)
default: $(TARGETS)

a.out:
	go build -o $@
a.out.lambda.list:
	go build -o $@ --tags lambda,list
a.out.lambda.add:
	go build -o $@ --tags lambda,add

clean:
	rm -f a.out*
.PHONY: clean