Launching an RDS instance in AWS - Mini Project: Build & Apply

Launching an RDS instance

📖 Scenario: You are setting up a simple database for a small web application. You want to launch an Amazon RDS instance to store your app's data securely and reliably.

🎯 Goal: Create an AWS CloudFormation template that launches a basic Amazon RDS instance with the specified settings.

📋 What You'll Learn

Use AWS CloudFormation YAML syntax

Create an RDS DB instance resource

Specify DB instance class, engine, and allocated storage

Set master username and password parameters

Add a DB subnet group referencing two subnets

Ensure the DB instance is publicly accessible

💡 Why This Matters

🌍 Real World

Launching an RDS instance is a common task when setting up backend databases for web applications or services in AWS.

💼 Career

Cloud architects and DevOps engineers often write CloudFormation templates to automate infrastructure deployment, including databases like RDS.

1

Create the CloudFormation template skeleton

Start by creating a CloudFormation template with the AWSTemplateFormatVersion set to '2010-09-09' and an empty Resources section.

AWS

AWSTemplateFormatVersion: '2010-09-09'
Resources:
  # Your code here

Hint

CloudFormation templates start with AWSTemplateFormatVersion and have a Resources section.

2

Add parameters for DB credentials

Add two parameters named DBUsername and DBPassword under Parameters. Set DBUsername as a string with default admin. Set DBPassword as a string with NoEcho true to hide the password.

AWS

AWSTemplateFormatVersion: '2010-09-09'
Parameters:
  # Your code here
Resources: {}

Hint

Parameters let you input values when launching the stack. Use NoEcho: true to keep passwords hidden.

3

Add a DB subnet group resource

Add a resource named DBSubnetGroup of type AWS::RDS::DBSubnetGroup. Set its DBSubnetGroupDescription to 'Subnet group for RDS' and SubnetIds to a list containing subnet-12345678 and subnet-87654321.

AWS

AWSTemplateFormatVersion: '2010-09-09'
Parameters:
  DBUsername:
    Type: String
    Default: admin
  DBPassword:
    Type: String
    NoEcho: true
Resources:
  # Your code here

Hint

DB subnet groups tell RDS which subnets to use for the database.

4

Add the RDS DB instance resource

Add a resource named MyDBInstance of type AWS::RDS::DBInstance. Set its DBInstanceClass to db.t3.micro, Engine to mysql, AllocatedStorage to 20, MasterUsername to !Ref DBUsername, MasterUserPassword to !Ref DBPassword, DBSubnetGroupName to !Ref DBSubnetGroup, and PubliclyAccessible to true.

AWS

AWSTemplateFormatVersion: '2010-09-09'
Parameters:
  DBUsername:
    Type: String
    Default: admin
  DBPassword:
    Type: String
    NoEcho: true
Resources:
  DBSubnetGroup:
    Type: AWS::RDS::DBSubnetGroup
    Properties:
      DBSubnetGroupDescription: 'Subnet group for RDS'
      SubnetIds:
        - subnet-12345678
        - subnet-87654321
  # Your code here

Hint

This resource launches the actual RDS database instance with your settings.

Practice

1. What is the main purpose of launching an Amazon RDS instance?

easy

A. To set up a virtual private network

B. To manually configure hardware for a database

C. To create a managed cloud database quickly

D. To write application code for database access

Solution

1. Step 1: Understand RDS service purpose

   Amazon RDS is a managed service that simplifies database setup and management.

2. Step 2: Identify the main benefit

   It allows quick creation of cloud databases without manual hardware setup.

3. Final Answer:

   To create a managed cloud database quickly -> Option C

4. Quick Check:

   RDS = managed cloud database creation [OK]

Hint: RDS means managed database, not manual hardware setup [OK]

Common Mistakes:

• Confusing RDS with manual server setup
• Thinking RDS is for network configuration
• Assuming RDS is for writing application code

2. Which of the following is a required parameter when launching an RDS instance using AWS Console?

easy

A. Database engine type (e.g., MySQL, PostgreSQL)

B. Operating system version of the server

C. IP address of the client machine

D. Number of application users

Solution

1. Step 1: Identify launch parameters for RDS

   When launching RDS, you must choose the database engine type like MySQL or PostgreSQL.

2. Step 2: Exclude unrelated parameters

   Operating system, client IP, or app users are not required inputs for RDS launch.

3. Final Answer:

   Database engine type (e.g., MySQL, PostgreSQL) -> Option A

4. Quick Check:

   Engine type is mandatory for RDS launch [OK]

Hint: Pick the database engine type, not unrelated details [OK]

Common Mistakes:

• Confusing OS version with database engine
• Providing client IP instead of DB settings
• Thinking user count is a launch parameter

3. Consider this AWS CLI command snippet to launch an RDS instance:

aws rds create-db-instance --db-instance-identifier mydb --db-instance-class db.t3.micro --engine mysql --master-username admin --master-user-password Pass1234 --allocated-storage 20

What will be the allocated storage size of the created RDS instance?

medium

A. Not specified, default used

B. 10 GB

C. 100 GB

D. 20 GB

Solution

1. Step 1: Locate storage parameter in command

   The parameter --allocated-storage 20 sets storage size to 20 GB.

2. Step 2: Confirm no other storage size overrides

   No other storage size is specified, so 20 GB is used.

3. Final Answer:

   20 GB -> Option D

4. Quick Check:

   Allocated storage = 20 GB [OK]

Hint: Look for --allocated-storage value in command [OK]

Common Mistakes:

• Assuming default storage without checking parameter
• Confusing instance class with storage size
• Ignoring the explicit storage size given

4. You tried launching an RDS instance but got an error: "InvalidParameterCombination: Storage size must be at least 20 GB for db.t3.micro". Your command was:

aws rds create-db-instance --db-instance-identifier testdb --db-instance-class db.t3.micro --engine postgres --master-username admin --master-user-password Pass1234 --allocated-storage 10

What is the cause of the error?

medium

A. Allocated storage size is below the minimum for the instance class

B. Master username is invalid

C. Engine type postgres is not supported

D. DB instance identifier is missing

Solution

1. Step 1: Analyze error message details

   The error says storage must be at least 20 GB for db.t3.micro, but 10 GB was given.

2. Step 2: Check command parameters

   The command uses --allocated-storage 10, which is too small for this instance class.

3. Final Answer:

   Allocated storage size is below the minimum for the instance class -> Option A

4. Quick Check:

   Storage size too small causes error [OK]

Hint: Check minimum storage size for instance class [OK]

Common Mistakes:

• Ignoring minimum storage requirements
• Blaming username or engine type incorrectly
• Missing required parameters in command

5. You want to launch an RDS instance with automatic backups enabled and a backup retention period of 7 days. Which configuration option should you set during launch to achieve this?

hard

A. Set MultiAZ to true

B. Set BackupRetentionPeriod to 7 and enable automatic backups

C. Set StorageEncrypted to true

D. Set PubliclyAccessible to true

Solution

1. Step 1: Identify backup settings for RDS

   Automatic backups require enabling backups and setting the retention period.

2. Step 2: Match configuration options

   BackupRetentionPeriod controls how many days backups are kept; enabling backups is necessary.

3. Step 3: Exclude unrelated options

   MultiAZ is for high availability, StorageEncrypted for encryption, and PubliclyAccessible for network access.

4. Final Answer:

   Set BackupRetentionPeriod to 7 and enable automatic backups -> Option B

5. Quick Check:

   BackupRetentionPeriod = 7 enables 7-day backups [OK]

Hint: BackupRetentionPeriod sets days for automatic backups [OK]

Common Mistakes:

• Confusing backup with MultiAZ or encryption settings
• Not enabling backups explicitly
• Setting unrelated network options