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Ginを用いたサーバーレスアプリケーションをAWS CDKでデプロイする方法

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はじめに

Glolang WebアプリケーションGinを用いたサーバーレスアプリケーションをAWS CDKを使ってAWS Lambdaにデプロイします

今回用いたコードはGitHubで公開しています。

環境

Golang: 1.20.4
AWS CDK: 2.96.0

ディレクトリ構成

├── gin
│   ├── bin
│   │   ├── bootstrap
│   │   └── myFunction.zip
│   ├── main.go
└── infra

Gin

Gin Tutorial

今回はGin Tutorialで作れるRESTful APIをデプロイしようと思います。

このTutorialを終えた後のmain.goは以下の通りです。 
package main

import (
    "net/http"

    "github.com/gin-gonic/gin"
)

// album represents data about a record album.
type album struct {
    ID     string  `json:"id"`
    Title  string  `json:"title"`
    Artist string  `json:"artist"`
    Price  float64 `json:"price"`
}

// albums slice to seed record album data.
var albums = []album{
    {ID: "1", Title: "Blue Train", Artist: "John Coltrane", Price: 56.99},
    {ID: "2", Title: "Jeru", Artist: "Gerry Mulligan", Price: 17.99},
    {ID: "3", Title: "Sarah Vaughan and Clifford Brown", Artist: "Sarah Vaughan", Price: 39.99},
}

func main() {
    router := gin.Default()
    router.GET("/albums", getAlbums)
    router.GET("/albums/:id", getAlbumByID)
    router.POST("/albums", postAlbums)

    router.Run("localhost:8080")
}

// getAlbums responds with the list of all albums as JSON.
func getAlbums(c *gin.Context) {
    c.IndentedJSON(http.StatusOK, albums)
}

// postAlbums adds an album from JSON received in the request body.
func postAlbums(c *gin.Context) {
    var newAlbum album

    if err := c.BindJSON(&newAlbum); err != nil {
        return
    }

    albums = append(albums, newAlbum)
    c.IndentedJSON(http.StatusCreated, newAlbum)
}

// getAlbumByID locates the album whose ID value matches the id
func getAlbumByID(c *gin.Context) {
    id := c.Param("id")

    for _, a := range albums {
        if a.ID == id {
            c.IndentedJSON(http.StatusOK, a)
            return
        }
    }
    c.IndentedJSON(http.StatusNotFound, gin.H{"message": "album not found"})
}

AWS Lambdaにデプロイするために書き換える

  1. 以下のパッケージをimportします 
    import (
	"context"
	"net/http"

	"github.com/aws/aws-lambda-go/events"
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/awslabs/aws-lambda-go-api-proxy/gin"
	"github.com/gin-gonic/gin"
)
    その後、以下のコマンドを実行します 
    go get .
  2. GinLambdaを宣言 
    var ginLambda *ginadapter.GinLambda
  3. func mainをfunc initに書き換え、以下のように変更する 
    func init() {
	router := gin.Default()
	router.GET("/albums", getAlbums)
	router.POST("/albums", postAlbums)
	router.GET("/albums/:id", getAlbumByID)

	ginLambda = ginadapter.New(router)
}
  4. Handler, main関数を用意する 
    func Handler(ctx context.Context, req events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
	return ginLambda.ProxyWithContext(ctx, req)
}

func main() {
	lambda.Start(Handler)
}
最終的にmain.goはこのようになります。 
package main

import (
	"context"
	"net/http"

	"github.com/aws/aws-lambda-go/events"
	"github.com/aws/aws-lambda-go/lambda"
	"github.com/awslabs/aws-lambda-go-api-proxy/gin"
	"github.com/gin-gonic/gin"
)

// album represents data about a record album.
type album struct {
	ID     string  `json:"id"`
	Title  string  `json:"title"`
	Artist string  `json:"artist"`
	Price  float64 `json:"price"`
}

// albums slice to seed record album data.
var albums = []album{
	{ID: "1", Title: "Blue Train", Artist: "John Coltrane", Price: 56.99},
	{ID: "2", Title: "Jeru", Artist: "Gerry Mulligan", Price: 17.99},
	{ID: "3", Title: "Sarah Vaughan and Clifford Brown", Artist: "Sarah Vaughan", Price: 39.99},
}

var ginLambda *ginadapter.GinLambda

func init() {
	router := gin.Default()
	router.GET("/albums", getAlbums)
	router.POST("/albums", postAlbums)
	router.GET("/albums/:id", getAlbumByID)

	ginLambda = ginadapter.New(router)
}

// getAlbums responds with the list of all albums as JSON.
func getAlbums(c *gin.Context) {
	c.IndentedJSON(http.StatusOK, albums)
}

// postAlbums adds an album from JSON received in the request body.
func postAlbums(c *gin.Context) {
	var newAlbum album

	if err := c.BindJSON(&newAlbum); err != nil {
		return
	}

	albums = append(albums, newAlbum)
	c.IndentedJSON(http.StatusCreated, newAlbum)
}

// getAlbumByID locates the album whose ID value matches the id
func getAlbumByID(c *gin.Context) {
	id := c.Param("id")

	for _, a := range albums {
		if a.ID == id {
			c.IndentedJSON(http.StatusOK, a)
			return
		}
	}
	c.IndentedJSON(http.StatusNotFound, gin.H{"message": "album not found"})
}

func Handler(ctx context.Context, req events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
	return ginLambda.ProxyWithContext(ctx, req)
}

func main() {
	lambda.Start(Handler)
}

AWS CDK

AWS CDKが初めての方

こちらのAWS Cloud Development Kit(AWS CDK)v2の、Getting startedを実際に行ってみるとわかりやすいです。

今回の実装ではTypeScriptを用います。

AWS Lambda, API Gateway

今回の以下のようなサーバーレスアーキテクチャーをAWS CDKで構築します。

AWS_Architecture.jpg

Gin側での準備

今回は、.zipファイルアーカイブを使用してGo Lambda関数をデプロイします。
AWS公式を参考に、以下を実行します。(maxOS/Linuxを想定しています。Windowsの方は左のAWS公式を参照してください。)

  1. main.goをコンパイルする
    x86_64 architectureの場合

    /gin
    $ GOOS=linux GOARCH=amd64 go build -tags lambda.norpc -o bin/bootstrap main.go

  2. zipファイルを作成する

    /gin
    $ zip bin/myFunction.zip bin/bootstrap

AWS CDK

  1. init

    /infra
    $ cdk init app --language typescript

  2. infra/lib/gin-lambda-stack.tsを以下のように変更し、それに合わせて、infra/bin/infra.ts内のstack名も変更します。

    gin-lambda-stack.ts
    /infra/lib/gin-lambda-stack.ts
    import {
  aws_s3_assets as assets,
  aws_lambda as lambda,
  aws_apigateway as gateway,
  Stack,
  StackProps,
  Duration,
} from "aws-cdk-lib";
import * as path from "path";
import { Construct } from "constructs";

export class GinLambdaStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
    super(scope, id, props);

    const lambdaAsset = new assets.Asset(this, "GinServerAsset", {
      path: path.join(__dirname, "../../gin/bin"),
    });

    const lambdaFn = new lambda.Function(this, "GinServer", {
      code: lambda.Code.fromBucket(lambdaAsset.bucket, lambdaAsset.s3ObjectKey),
      timeout: Duration.minutes(5),
      runtime: lambda.Runtime.PROVIDED_AL2,
      handler: "main",
    });

    new gateway.LambdaRestApi(
      this,
      "GinServerLambdaEndpoint",
      {
        handler: lambdaFn,
      }
    )
  }
}

  3. デプロイ

    /infra
    $ cdk bootstrap

    デプロイ後にAPI endpointが表示されます

    /infra
    $ cdk deploy

     ✅  InfraStack

✨  Deployment time: 32.11s

Outputs:
InfraStack.GinServerLambdaEndpoint******** = https://**********.execute-api.<region>.amazonaws.com/prod/

    実際にAPIを叩くと、Gin Tutorialと同じレスポンスが返ってきます

    任意の場所
    $ curl https://**********.execute-api.<region>.amazonaws.com/prod/albums

    [
    {
        "id": "1",
        "title": "Blue Train",
        "artist": "John Coltrane",
        "price": 56.99
    },
    {
        "id": "2",
        "title": "Jeru",
        "artist": "Gerry Mulligan",
        "price": 17.99
    },
    {
        "id": "3",
        "title": "Sarah Vaughan and Clifford Brown",
        "artist": "Sarah Vaughan",
        "price": 39.99
    }
]

参考文献

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