Data Ingestion using Database Migration Service(DMS) and Lambda

Overview

The AWS Database Migration Service(DMS) is a managed service to migrate data into AWS. It can replicate data from operational databases and data warehouses (on premises or AWS) to a variety of targets, including S3 datalakes. In this architecture, DMS is used to capture changed records from relational databases on RDS or EC2 and write them into S3. AWS Lambda, a serverless compute service, is used to transform and partition datasets based on their arrival time in S3 for better query performance.

Data Ingestion using DMS and Lambda

Architecture Component Walkthrough

1. Create a Relational databases on EC2 or RDS within a VPC.

2. Create a Staging S3 location to store changes captured by DMS.

3. Create a Replication Instance using the DMS API's or console
4. Specify the Source & Target Endpoints for the Replication Instance.
5. Create an IAM role for AWS Lambda which has read access on the staging S3 bucket and write access on target datalake location.
6. Create a Lambda function to trigger custom code execution with s3:ObjectCreated:* requests to the staging S3 bucket. The function writes the same objects to the target datalake location on S3 with partitions based on the LastModified metadata attribute of S3 objects.
7. Create a DMS Task to migrate data from your source system to target location.
8. The DMS Replication Instance will then connect to the source via elastic network interface(ENI), and write to the S3 staging location. AWS Lambda will receive the PutObject events, and use the S3 Copy API to reorganise the data into your datalake.

Sample Lambda Function Using Python

from datetime import datetime
import boto3
import os

s3 = boto3.client('s3')
target_bucket = os.environ['TARGET_S3_BUCKET']
target_s3_prefix = os.environ['TARGET_S3_PREFIX']# Please don't use '/' at the end of TARGET_S3_PREFIX variable

def lambda_handler(event, context):

    print("Initializing S3 copy utility for DMS...")
    for object in event['Records']:
        try:
            input_bucket_name=object['s3']['bucket']['name']
            input_key = object['s3']['object']['key']
            print("Initializing copy of input file: s3://{}/{}".format(input_bucket_name, input_key))
            input_file_basename = os.path.basename(object['s3']['object']['key'])
            if target_s3_prefix is None or target_s3_prefix == '':
                partitioned_prefix = s3.head_object(Bucket=input_bucket_name,Key=input_key)['LastModified'].strftime("/year=%Y/month=%m/day=%d/hour=%H/")
            else:
                partitioned_prefix =  target_s3_prefix + s3.head_object(Bucket=input_bucket_name,Key=input_key)['LastModified'].strftime("/year=%Y/month=%m/day=%d/hour=%H/")
                #S3 headObject API is used to fetch LastModified metadata from the S3 object.
            print("Starting copy of input S3 object to s3://{}/{}/{}".format(target_bucket, partitioned_prefix, input_file_basename))
            s3.copy_object(CopySource = {'Bucket': object['s3']['bucket']['name'], 'Key': object['s3']['object']['key']}, Bucket=target_bucket, Key=partitioned_prefix + input_file_basename )
            print("S3 key was successfully copied to {}".format(target_bucket))

        except Exception as e:
            print(e)
            print('Error copying object to {}'.format(target_bucket))
            raise e

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