AWS S3 + AWS Lambda = <3

Following along with new best friend, this dude

The setup

1. IAM > Roles > Create Role
   • Select lambda
   • Search AWSLambdaExecute in policies – This provides log access and s3 read/write access
   • Skip tags
   • Review: lambda-s3-role for name, all else same
2. S3 > Create Bucket
   • unique name
   • click create on left side
3. Lambda > Create Function
   • Author from scratch
   • Create descriptive name like putUserDataFromS3
   • Make sure node.js 8 + selected
   • Choose existing role > select role we just created lambda-s3-role
   • Create Function

The function

1. Create Trigger for S3
   • Designer > add trigger > s3
   • Configure Trigger – bucket we just created – event type: change to put (to only trigger when we upload) – suffix (limit to just .json)
   • Add
2. Function Code

const AWS = require('aws-sdk');
const s3 = new AWS.S3();

exports.handler = async (event) => {
    const { name } = event.Records[0].s3.bucket;
    const { key } = event.Records[0].s3.object;
    
    const params = {
        Bucket: name,
        Key: key
    }
    
    try {
        const data = await s3.getObject(params).promise();
        const usersStr = data.Body.toString();
        const userJSON = JSON.parse(usersStr);
        console.log(`Users ::: ${usersStr}`);
    } catch (err) {
        console.log(err)
    }
};

1. Test by uploading to bucket!
   • Go to bucket and upload json file
   • Go back to lambda page > Monitoring > Cloud watch
   • Click event, observe!

Adding to the DB

1. Create Users Table (we did this in link-to-pt1)
   • Get the ARN Amazon Resource Name (ARN) arn:aws:dynamodb:us-west-2:386305625872:table/Users
2. Update IAM Role to have DB write permissions
   • Roles > lambda-s3-role
   • Add inline ppliciy
   • add service > dynamo DB
   • add actions put item
   • expand resources
   • paste in the ARN.
   • Review policy, give name DynamoDBWritePolicy
   • Create Policy
3. Update Lambda
   • Put first entry into data file

const AWS = require('aws-sdk');
const s3 = new AWS.S3();
const documentClient = new AWS.DynamoDB.DocumentClient();

exports.handler = async (event) => {
    const { name } = event.Records[0].s3.bucket;
    const { key } = event.Records[0].s3.object;
    
    const getObjectParams = {
        Bucket: name,
        Key: key
    }
    
    try {
        const s3Data = await s3.getObject(getObjectParams).promise();
        const usersStr = s3Data.Body.toString();
        const usersJSON = JSON.parse(usersStr);
        console.log(`Users ::: ${usersStr}`);
        
        const { id, firstname, lastname } = usersJSON[0];
        
        const putParams = {
            TableName: "Users",
            Item: {
                id: id,
                firstname: firstname,
                lastname: lastname
            }
        }
        
        const putItemData = await documentClient.put(putParams).promise()
        console.log(putItemData);
        
    } catch (err) {
        console.log(err)
    }
};

1. Test!
   • Delete users.json and reupload