CloudWatch Events (EventBridge) in AWS - Mini Project: Build & Apply

Create a CloudWatch EventBridge Rule to Trigger a Lambda Function

📖 Scenario: You are working as a cloud engineer for a company. They want to automatically run a Lambda function every day at 6 AM UTC to perform daily cleanup tasks.You will create an EventBridge rule that triggers the Lambda function on schedule.

🎯 Goal: Build an EventBridge rule with a cron schedule expression that triggers a Lambda function named DailyCleanupFunction every day at 6 AM UTC.

📋 What You'll Learn

Create an EventBridge rule named DailyCleanupRule with a cron schedule expression for 6 AM UTC daily

Set the rule's state to ENABLED

Add the Lambda function DailyCleanupFunction as the target of the rule

💡 Why This Matters

🌍 Real World

Automating tasks on a schedule is common in cloud environments. EventBridge rules help trigger Lambda functions or other services without manual intervention.

💼 Career

Cloud engineers and DevOps professionals often create scheduled events and connect them to serverless functions for automation and maintenance.

1

Create the EventBridge rule resource

Create an AWS CloudFormation resource of type AWS::Events::Rule named DailyCleanupRule with a ScheduleExpression set to cron(0 6 * * ? *) and State set to ENABLED.

AWS

# Your CloudFormation template starts here
# Define the EventBridge rule resource named DailyCleanupRule

Need a hint?

The cron expression cron(0 6 * * ? *) means 6 AM UTC every day.

2

Add the Lambda function target to the rule

Add a Targets property to the DailyCleanupRule resource. Set it to a list with one target object that has Arn set to !GetAtt DailyCleanupFunction.Arn and Id set to DailyCleanupTarget.

AWS

Resources:
  DailyCleanupRule:
    Type: AWS::Events::Rule
    Properties:
      ScheduleExpression: 'cron(0 6 * * ? *)'
      State: ENABLED
      # Add Targets property here

Need a hint?

The Targets property is a list of objects. Each target needs an Arn and an Id.

3

Define the Lambda function resource

Create an AWS CloudFormation resource named DailyCleanupFunction of type AWS::Lambda::Function. Set Handler to index.handler, Runtime to python3.12, and Role to arn:aws:iam::123456789012:role/lambda-execution-role. Set Code to an inline zip with a single file index.py containing a simple handler function.

AWS

Resources:
  DailyCleanupRule:
    Type: AWS::Events::Rule
    Properties:
      ScheduleExpression: 'cron(0 6 * * ? *)'
      State: ENABLED
      Targets:
        - Arn: !GetAtt DailyCleanupFunction.Arn
          Id: DailyCleanupTarget

# Define the DailyCleanupFunction Lambda resource below

Need a hint?

The Lambda function needs a role ARN for execution permissions.

4

Add permission for EventBridge to invoke the Lambda function

Add an AWS CloudFormation resource named AllowEventBridgeInvoke of type AWS::Lambda::Permission. Set FunctionName to !Ref DailyCleanupFunction, Action to lambda:InvokeFunction, Principal to events.amazonaws.com, and SourceArn to !GetAtt DailyCleanupRule.Arn.

AWS

Resources:
  DailyCleanupRule:
    Type: AWS::Events::Rule
    Properties:
      ScheduleExpression: 'cron(0 6 * * ? *)'
      State: ENABLED
      Targets:
        - Arn: !GetAtt DailyCleanupFunction.Arn
          Id: DailyCleanupTarget
  DailyCleanupFunction:
    Type: AWS::Lambda::Function
    Properties:
      Handler: index.handler
      Runtime: python3.12
      Role: arn:aws:iam::123456789012:role/lambda-execution-role
      Code:
        ZipFile: |
          def handler(event, context):
              return 'Cleanup done'

# Add Lambda permission resource here

Need a hint?

This permission allows EventBridge to call your Lambda function.