The purpose of this repository is to demonstrate the power of built-in Step Functions features that saves on building Lambda functions. The difference can be seen between the statemachine/before.asl.yaml and statemachine/after.asl.yaml workflow definitions.
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 - Code for the application's Lambda functions to check the value of, buy, or sell shares of a stock.
- statemachines - Definition for the state machine that orchestrates the stock trading workflow.
- samplefiles - Files that can be put in the bucket to test the application
- template.yaml - A template that defines the application's AWS resources.
This application creates an mock data processing workflow which reads two JSON objects from an S3 bucket, merges them and stores the result in a DynamoDB table.
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, S3 buckets and a DynamoDB table. 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.
If you prefer to use an integrated development environment (IDE) to build and test the Lambda functions within your application, you can use the AWS Toolkit. The AWS Toolkit is an open source plug-in for popular IDEs that uses the SAM CLI to build and deploy serverless applications on AWS. The AWS Toolkit also adds a simplified step-through debugging experience for Lambda function code. See the following links to get started:
The AWS Toolkit for VS Code includes full support for state machine visualization, enabling you to visualize your state machine in real time as you build. The AWS Toolkit for VS Code includes a language server for Amazon States Language, which lints your state machine definition to highlight common errors, provides auto-complete support, and code snippets for each state, enabling you to build state machines faster.
The Serverless Application Model Command Line Interface (SAM CLI) is an extension of the AWS CLI that adds functionality for building and testing Lambda applications. It uses Docker to run your functions in an Amazon Linux environment that matches Lambda.
To use the SAM CLI, you need the following tools:
- SAM CLI - Install the SAM CLI
- Python 3 installed
To build and deploy your application for the first time, run the following in your shell:
sam build
sam deploy --guidedThe 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_IAMvalue forcapabilitiesmust be provided. If permission isn't provided through this prompt, to deploy this example you must explicitly pass--capabilities CAPABILITY_IAMto thesam deploycommand. - 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 deploywithout parameters to deploy changes to your application.
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