Read replicas for performance in AWS - Mini Project: Build & Apply

Read replicas for performance

📖 Scenario: You manage a database for a popular online store. The main database handles all the writes like adding new orders. But many users also read product details and reviews. To keep the website fast, you want to add read replicas that copy data from the main database. This way, read requests can go to replicas, reducing load on the main database.

🎯 Goal: Create an AWS RDS instance with one read replica to improve read performance. You will first define the main database, then configure a read replica, and finally complete the setup to allow read traffic to the replica.

📋 What You'll Learn

Create a main RDS instance named main-db with MySQL engine version 8.0.28

Create a read replica named read-replica-1 of main-db

Enable public accessibility for both instances

Set the instance class to db.t3.micro for both

Configure the read replica to allow read traffic

💡 Why This Matters

🌍 Real World

Many web applications use read replicas to handle large volumes of read requests without slowing down the main database that handles writes.

💼 Career

Cloud architects and DevOps engineers often configure read replicas to optimize database performance and scalability.

1

Create the main RDS instance

Write AWS CloudFormation YAML code to create an RDS DB instance named MainDB with the identifier main-db. Use the MySQL engine version 8.0.28, instance class db.t3.micro, and set PubliclyAccessible to true.

AWS

# Define the main RDS instance resource here
# Your code here

Need a hint?

Use AWS::RDS::DBInstance resource type and set the properties exactly as specified.

2

Add the read replica configuration

Add a new resource named ReadReplica1 to create a read replica of MainDB. Set the SourceDBInstanceIdentifier to main-db, use the instance class db.t3.micro, and set PubliclyAccessible to true.

AWS

Resources:
  MainDB:
    Type: AWS::RDS::DBInstance
    Properties:
      DBInstanceIdentifier: main-db
      Engine: mysql
      EngineVersion: 8.0.28
      DBInstanceClass: db.t3.micro
      PubliclyAccessible: true

# Add the read replica resource below
# Your code here

Need a hint?

Use SourceDBInstanceIdentifier property to link the replica to the main DB.

3

Configure the read replica for read traffic

Add the property DBSubnetGroupName with value default to both MainDB and ReadReplica1 resources to allow network access for read traffic.

AWS

Resources:
  MainDB:
    Type: AWS::RDS::DBInstance
    Properties:
      DBInstanceIdentifier: main-db
      Engine: mysql
      EngineVersion: 8.0.28
      DBInstanceClass: db.t3.micro
      PubliclyAccessible: true
      # Add DBSubnetGroupName here
  ReadReplica1:
    Type: AWS::RDS::DBInstance
    Properties:
      DBInstanceIdentifier: read-replica-1
      SourceDBInstanceIdentifier: main-db
      DBInstanceClass: db.t3.micro
      PubliclyAccessible: true
      # Add DBSubnetGroupName here
# Your code here

Need a hint?

Adding DBSubnetGroupName helps the instances be reachable in the network.

4

Enable read traffic by setting the appropriate tags

Add a tag with Key set to Purpose and Value set to ReadReplica to the ReadReplica1 resource to indicate its role for read traffic.

AWS

Resources:
  MainDB:
    Type: AWS::RDS::DBInstance
    Properties:
      DBInstanceIdentifier: main-db
      Engine: mysql
      EngineVersion: 8.0.28
      DBInstanceClass: db.t3.micro
      PubliclyAccessible: true
      DBSubnetGroupName: default
  ReadReplica1:
    Type: AWS::RDS::DBInstance
    Properties:
      DBInstanceIdentifier: read-replica-1
      SourceDBInstanceIdentifier: main-db
      DBInstanceClass: db.t3.micro
      PubliclyAccessible: true
      DBSubnetGroupName: default
      # Add Tags here
# Your code here

Need a hint?

Tags help identify the role of the resource in AWS.