Project Bellflower : Step Function Callback Pattern Example (Amazon SQS, Amazon SNS, Lambda).

A State Machine demonstrating Lambda orchestration with a third party application using S3 and SQS and Lambda Callback functionality and notifying the users using SNS notification.

Description

This is demonstration of a State Machine with Lambda, SNS, SQS and S3. The processing Lambda generates a payload and pushes to a SQS Queue. An integration Lambda processes the payload and send a file with task token to S3 outbound folder. An Business Application processes the information and sends a success trigger to the S3 inbound folder. The integration Lambda reads the success trigger and sends a success signal to the State Machine and resumes processing. Once processing completes, the State Machine sends a Success notification to SNS Topic. If the processing Lambda fails after 3 retries the State Machine fails and a Failure notification is sent to the SNS Topic. The entire stack is created using CloudFormation.

Getting Started

Dependencies

• Create a Customer Managed KMS Key in the region where you want to create the stack.
• Modify the KMS Key Policy to let the IAM user encrypt / decrypt using any resource using the created KMS Key. Following the kms-key-policy.json and use it after replacing the AWS Account Id.

Installing

• Clone the repository https://github.com/subhamay-cloudworks/0038-bellflower-cft
• Create a S3 bucket to store the CloudFormation nested stack templates and the Lambda code zip files.
• Create the folders - bellflower/cft/nested-stacks, bellflower/cft/cross-stacks, bellflower/code/python, bellflower/cft/state-machine
• Upload the following YAML templates to bellflower/cft/nested-stacks
  • iam-role-stack.yaml
  • lambda-function-stack.yaml
  • s3-stack.yaml
  • sns-stack.yaml
  • sqs-stack
  • cloudwatch-stack.yaml
• Upload the following YAML templates to bellflower/cft/cross-stacks
  • custom-resource-lambda-stack.yaml
• Zip and Upload the following Python files to bellflower/code/python
  • processing_lambda.py (processing_lambda.zip)
  • integration_lambda.py (integration_lambda.zip)
• Upload the ASL file state-machine.asl.json to bellflower/cft/state-machine
• Create the cross-stack using the template custom-resource-lambda-stack.yaml by using the S3 url and pass the appropriate parameters and note the cross stack name.
• Create the entire stack by using the root stack template bellflower/cft/bellflower-root-stack.yaml and providing the required parameters and the s3 cross stack name created in the previous step.

Executing program

• Execute the state machine with default payload. You can use the sample provided below:

{
    "Comment": "Bellflower - Callback Pattern Example (Amazon SQS, Amazon SNS, Lambda)"
}

• Get the UUID of the execution from the log or from the S3 bucket outbound folder.
• Create a success.json file in the bucket s3:///inbound//
• Copy the success.json to S3 inbound folder

aws s3 cp success.json s3://<s3 bucket uri>/inbound/<UUID>/

Help

Post message in my blog (https://blog.subhamay.com)

Authors

Contributors names and contact info

Subhamay Bhattacharyya - subhamay.aws@gmail.com

Version History

• 0.1
  • Initial Release

License

This project is licensed under Subhamay Bhattacharyya. All Rights Reserved.

Acknowledgments

AWS Documentation (https://docs.aws.amazon.com/step-functions/latest/dg/callback-task-sample-sqs.html)