Create Multi-workflow Applications using AWS SAM

By tigonguyen |
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Throughout this blog post, we will explore the code and functionality of these files in detail. By following the steps provided, you can deploy and experience the power of the multi-workflow application built using the AWS Serverless Application Model.

For a comprehensive view of the code discussed throughout this blog post, please refer to the complete set of code available here.

Introduction to AWS Serverless Application Model (SAM)

The AWS Serverless Application Model (AWS SAM) is a toolkit that improves the developer experience of building and running serverless applications on AWS. AWS SAM consists of two primary parts:

  1. AWS SAM template specification – An open-source framework that you can use to define your serverless application infrastructure on AWS.

  2. AWS SAM command line interface (AWS SAM CLI) – A command line tool that you can use with AWS SAM templates and supported third-party integrations to build and run your serverless applications.

Application Overview

Architecture Diagram

Application Description

This project contains source code and supporting files for a serverless application that you can deploy with the SAM CLI. It includes the following files and folders:

  • functions: This directory contains the code for the Lambda functions responsible for tasks such as checking stock values, purchasing shares, and selling shares.
  • statemachines: Here, you’ll find the state machine definition that orchestrates the stock trading workflow.
  • template.yaml: This YAML file serves as the application’s template, defining its AWS resources.
  • samconfig.toml: The samconfig.toml file is a configuration file used by the SAM CLI. It allows you to specify deployment parameters such as the AWS Region, the deployment bucket name, and other settings.

This application creates a mock stock trading workflow which runs on a pre-defined schedule (note that the schedule is disabled by default to avoid incurring charges). It demonstrates the power of Step Functions to orchestrate Lambda functions and other AWS resources to form complex and robust workflows, coupled with event-driven development using Amazon EventBridge.

AWS Step Functions lets you coordinate multiple AWS services into serverless workflows so you can build and update apps quickly. Using Step Functions, you can design and run workflows that stitch together services, such as AWS Lambda, AWS Fargate, and Amazon SageMaker, into feature-rich applications.

The application uses several AWS resources, including Step Functions state machines, Lambda functions and an EventBridge rule trigger. These resources are defined in the template.yaml file in this project. You can update the template to add AWS resources through the same deployment process that updates your application code.

Quick Usage and Clean Up

To build and deploy your application for the first time, run the following in your shell:

sam build
sam deploy --guided

The first command will build the source of your application. The second command will package and deploy your application to AWS, with a series of prompts:

  • Stack Name: The name of the stack to deploy to CloudFormation. This should be unique to your account and region, and a good starting point would be something matching your project name.
  • AWS Region: The AWS region you want to deploy your app to.
  • Confirm changes before deploy: If set to yes, any change sets will be shown to you before execution for manual review. If set to no, the AWS SAM CLI will automatically deploy application changes.
  • Allow SAM CLI IAM role creation: Many AWS SAM templates, including this example, create AWS IAM roles required for the AWS Lambda function(s) included to access AWS services. By default, these are scoped down to minimum required permissions. To deploy an AWS CloudFormation stack which creates or modifies IAM roles, the CAPABILITY_IAM value for capabilities must be provided. If permission isn’t provided through this prompt, to deploy this example you must explicitly pass --capabilities CAPABILITY_IAM to the sam deploy command.
  • Save arguments to samconfig.toml: If set to yes, your choices will be saved to a configuration file inside the project, so that in the future you can just re-run sam deploy without parameters to deploy changes to your application.

To delete the sample application that you created, use the AWS CLI. Assuming you used your project name for the stack name, you can run the following:

sam delete --stack-name "sam-app"

References

See the AWS SAM developer guide for an introduction to SAM specification, the SAM CLI, and serverless application concepts.

Next, you can use AWS Serverless Application Repository to deploy ready to use Apps that go beyond hello world samples and learn how authors developed their applications: AWS Serverless Application Repository main page