Scheduled EC2 Instance Type Modification using Lambda and CloudWatch Events

modify-ec2-instance-type.js

// Demonstration video can be found at: https://youtu.be/_gJyK1-NGq8

// ModifyEC2InstanceType

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

exports.handler = (event, context, callback) => {
    const { instanceId, instanceRegion, instanceType } = event;
    
    const ec2 = new AWS.EC2({ region: instanceRegion });
    
    Promise.resolve()
        .then(() => ec2.stopInstances({ InstanceIds: [instanceId] }).promise())
        .then(() => ec2.waitFor('instanceStopped', { InstanceIds: [instanceId] }).promise())
        .then(() => ec2.modifyInstanceAttribute({InstanceId: instanceId, InstanceType: { Value: instanceType } }).promise())
        .then(() => ec2.startInstances({ InstanceIds: [instanceId] }).promise())
        .then(() => callback(null, `Successfully modified ${event.instanceId} to ${event.instanceType}`))
        .catch(err => callback(err));
};

Even after 4 years, still works like a charm. Thnx!