Scheduled Start/Stop of EC2 Instances using Lambda and Serverless

handler.js

'use strict';

const AWS = require('aws-sdk');

module.exports.start = (event, context, callback) => {
  const ec2 = new AWS.EC2({ region: event.region });

  ec2.startInstances({ InstanceIds: [event.id] }).promise()
    .then(() => callback(null, `Successfully started ${event.id}`))
    .catch(err => callback(err));
};

module.exports.stop = (event, context, callback) => {
  const ec2 = new AWS.EC2({ region: event.region });

  ec2.stopInstances({ InstanceIds: [event.id] }).promise()
    .then(() => callback(null, `Successfully stopped ${event.id}`))
    .catch(err => callback(err));
};

serverless.yml

service: start-stop-ec2-instances

provider:
  name: aws
  runtime: nodejs6.10
  stage: prod
  region: eu-west-1
  iamRoleStatements:
    - Effect: "Allow"
      Action:
        - "ec2:StartInstances"
        - "ec2:StopInstances"
      Resource: "*"

custom:
  instanceId: %EC2_INSTANCE_ID%
  start: cron(30 6 * * ? *)
  stop: cron(30 18 * * ? *)

functions:
  start:
    handler: handler.start
    events:
      - schedule:
          rate: ${self:custom.start}
          input:
            id: ${self:custom.instanceId}
            region: ${self:provider.region}
  stop:
    handler: handler.stop
    events:
      - schedule:
          rate: ${self:custom.stop}
          input:
            id: ${self:custom.instanceId}
            region: ${self:provider.region}