試験日まで毎日励ますサーバーレスLINE Botを作ろう(AWS CDK編)

const cdk = require('aws-cdk-lib');
const lambda = require('aws-cdk-lib/aws-lambda');
const apigw = require('aws-cdk-lib/aws-apigateway');
const dynamodb = require('aws-cdk-lib/aws-dynamodb');
const iam = require('aws-cdk-lib/aws-iam');
const events = require('aws-cdk-lib/aws-events');
const targets = require('aws-cdk-lib/aws-events-targets');

class CdkWorkshopStack extends cdk.Stack {
  /**
   * @param {Construct} scope
   * @param {string} id
   * @param {StackProps=} props
   */

  constructor(scope, id, props) {
    super(scope, id, props);
   
    // DynamoDBの準備
    const examTable = new dynamodb.Table(this, 'Exam', {
      partitionKey: {
        name: 'test_name',
        type: dynamodb.AttributeType.STRING
      },
      tableName: 'Exam'
    });

    // Lambda実行ロールにSSMへのアクセスを許可する
    const executionLambdaRole = new iam.Role(this, 'MyLambdaExecutionRole',
      {
        roleName: 'my-lambda-execution-role',
        assumedBy: new iam.ServicePrincipal('lambda.amazonaws.com'),
        managedPolicies: [
          iam.ManagedPolicy.fromAwsManagedPolicyName(
            'service-role/AWSLambdaBasicExecutionRole'
          ),
          iam.ManagedPolicy.fromAwsManagedPolicyName(
            'AmazonSSMReadOnlyAccess'
          )
        ]
      }
    );

    // 依存関係をLambda Layerとして保存
    const layer = new lambda.LayerVersion(this, 'MyLayer', {
      code: lambda.Code.fromAsset('lambda-layer'),
      compatibleRuntimes: [lambda.Runtime.NODEJS_16_X]
    });

    // 試験データ登録側のLambda関数を作成する
    const register = new lambda.Function(this, 'RegisterHandler', {
      runtime: lambda.Runtime.NODEJS_16_X,
      code: lambda.Code.fromAsset('lambda-register'),
      handler: 'register.handler',
      role: executionLambdaRole,
      layers: [layer]
    });

    // LINEにメッセージを送るLambda関数の定義
    const pushMessage = new lambda.Function(this, 'PushMessageHandler', {
      runtime: lambda.Runtime.NODEJS_16_X,
      code: lambda.Code.fromAsset('lambda-push-msg'),
      handler: 'pushMessage.handler',
      role: executionLambdaRole,
      layers: [layer]
    });

    // DynamoDBへの読み書き許可
    examTable.grantReadWriteData(register);
    examTable.grantReadData(pushMessage);

    // API Gatewayの定義
    new apigw.LambdaRestApi(this, 'Endpoit', {
      handler: register
    });

    // EventBrigeでLambdaを定期実行
    new events.Rule(this, 'ScheduleRule', {
      schedule: events.Schedule.cron({ minute: '0', hour: '13' }),
      targets: [new targets.LambdaFunction(pushMessage, {})]
    });
  }
}

module.exports = { CdkWorkshopStack }

const AWS = require("aws-sdk");
const line = require('@line/bot-sdk');
const ssm = new AWS.SSM();
const dynamo = new AWS.DynamoDB.DocumentClient();

// SSM ParameterStoreから値を取得する
const getSSMParameter = async (name) => {
  let result = await ssm.getParameter({
    Name: name,
    WithDecryption: true
  }).promise();

  return result.Parameter.Value;
};

// DynamoDBに登録する
const insert = async exams => {
  await dynamo
    .put({
      TableName: "Exam",
      Item: {
        test_name: exams[0],
        test_day: exams[1],
        purpose: exams[2]
      }
    })
    .promise();
};

exports.handler = async (event, context, callback) => {
  const body = JSON.parse(event.body).events[0];
  const exams = body.message.text.split(":");

  // SSM ParameterStoreから値を取得する
  let LINE_ACCESS_KEY = await getSSMParameter('LINE_ACCESS_KEY');
  const client = new line.Client({
    channelAccessToken: LINE_ACCESS_KEY
  });

  let message;
  if (exams.length === 3) {
    insert(exams);  // DynamoDBに登録
    message = '登録したよ';
  } else {
    message = '登録したい試験を「試験名:日付(YYYY-MM-DD):目的」の形式で入力してね！';
  }

  await client.replyMessage(body.replyToken, {
    type: 'text',
    text: message
  });
};

const dayjs = require('dayjs');
const AWS = require("aws-sdk");
const line = require('@line/bot-sdk');
const dynamo = new AWS.DynamoDB.DocumentClient();

let params = {
  TableName: 'Exam',
};

const ssm = new AWS.SSM();
const generateText = (test_name, day, purpose) => {
  const messages = [
    '君の本気はそんなもんじゃないでしょ？',
    '今日は何をしたんだい？内省してごらん？',
    '間にあいそ？',
    '明日は今日の倍がんばろうな',
    `目的は ${purpose} って言ってたよね？達成できそう？`
  ];

  return `${test_name}まで残り${day}日だよ！\n`
    + messages[Math.floor(Math.random() * messages.length)];
};

// SSM ParameterStoreから値を取得する
const getSSMParameter = async (name) => {
  let result = await ssm.getParameter({
    Name: name,
    WithDecryption: true
  }).promise();

  return result.Parameter.Value;
};

// 試験までの残り日数を計算
const calcRemainingDays = test_day => dayjs(test_day).diff(dayjs(), 'd');

const generateMessages = items => {
  let messages = [];
  items.forEach(function (exam, index) {
    messages.push({
      type: 'text',
      text: generateText(exam.test_name,
        calcRemainingDays(exam.test_day),
        exam.purpose)
    });
  });

  return messages;
};

exports.handler = async (event, context, callback) => {
  const LINE_ACCESS_KEY = await getSSMParameter('LINE_ACCESS_KEY');
  const USER_ID = await getSSMParameter('LINE_USER_ID');

  const client = new line.Client({
    channelAccessToken: LINE_ACCESS_KEY
  });

  // dynamoDBから取得
  let examObj = await dynamo.scan(params).promise();

  // メッセージ生成
  let replyMessage = generateMessages(examObj.Items);
  await client.pushMessage(USER_ID, replyMessage);
};