Calling one Lambda from another Lambda on AWS | Lambda Chaining

How to Trigger One Lambda from Another Lambda on AWS

Step 1: Create Two Lambdas

• Begin by creating two Lambda functions on AWS. These functions will be used to trigger one another.
• You can create basic Lambda functions by writing the required code in the AWS Lambda console.

Step 2: Set Up AWS SDK Client Object

• In your first Lambda function, create an AWS SDK client object. This object will be used to invoke the second Lambda function.
• Ensure you have the necessary permissions and access to AWS services.

Step 3: Invoke the Second Lambda Function

• Call the invoke method on the client object created in the first Lambda function.
• Provide the ARN (Amazon Resource Name) of the second Lambda function as the function name parameter.
• Include any payload or message that you want to send from the first Lambda to the second Lambda.

Step 4: Configure IAM Policies

• To allow the first Lambda function to invoke the second Lambda function, you need to configure IAM (Identity and Access Management) policies.
• Create an inline policy in the AWS IAM console for the role associated with the first Lambda function.
• Add permissions to invoke the second Lambda function by specifying the actions invokeFunction and invokeAsync.

Step 5: Attach the IAM Policy

• Attach the IAM policy created in the previous step to both Lambda functions.
• This ensures that the first Lambda function has the necessary permissions to trigger the second Lambda function.

Step 6: Test the Lambda Invocation

• Trigger the first Lambda function to invoke the second Lambda function.
• Check the CloudWatch logs to verify that the message or payload sent from the first Lambda function is received and processed by the second Lambda function.

Step 7: Monitor the Logs

• Monitor the CloudWatch logs to view the output and messages generated by both Lambda functions.
• Ensure that the invocation and communication between the two Lambdas are successful.

By following these steps, you can effectively trigger one Lambda function from another Lambda function on AWS, enabling you to create efficient serverless architectures and workflows.