lambda-gifbot

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.

• app.js - Code for the Lambda function.
• event.json - Sample event that you can use to invoke the function.
• template.yaml - A template that defines the application's AWS resources.

The application uses several AWS resources, including Lambda functions and an IAM Role. 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.

AWS SSO Configuration

AWS Management Account - mgmt Profile

If AWS SSO has not yet been configured, follow instructions in https://github.com/caseconsulting/expense-app-api/blob/master/README.md#aws-sso-configuration to complete initial SSO configuration. lambda-gifbot is deployed to the CASE Management AWS account, so you need to make sure you've configured a mgmt profile for the Case Consulting Management AWS account.

AWS SSO Login

To explicitly obtain AWS credentials from AWS SSO, run aws sso login --profile mgmt. Your web browser should open a new tab, where you should be required to login to Google with your @consultwithcase.com email address (unless you recently did so) and then press the Allow button to explicitly permit the authorize request.

To remove AWS credentials, run aws sso logout --profile mgmt. This will also clear any authorization. Therefore, a subsequent login will launch the web browser again for a new authorization request.

Deploy the sample application

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. It can also emulate your application's build environment and API.

To use the SAM CLI, you need the following tools.

• SAM CLI - Install the SAM CLI
• Node.js - Install Node.js, including the NPM package management tool.
• Docker - Install Docker community edition

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 modified 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.

You can find your API Gateway Endpoint URL in the output values displayed after deployment.

Use the SAM CLI to build and test locally

Build your application with the sam build command.

lambda-gifbot$ sam build

The SAM CLI installs dependencies defined in package.json, creates a deployment package, and saves it in the .aws-sam/build folder.

Test a single function by invoking it directly with a test event. An event is a JSON document that represents the input that the function receives from the event source.

Run functions locally and invoke them with the sam local invoke command.

lambda-gifbot$ sam local invoke GifBotFunction --event event.json

The SAM CLI can also emulate your application's API. Use the sam local start-api to run the API locally on port 3000.

sam-app$ sam local start-api
sam-app$ curl http://localhost:3000/

The SAM CLI reads the application template to determine the API's routes and the functions that they invoke. The Events property on each function's definition includes the route and method for each path.

Events:
  GifBot:
    Type: Api
    Properties:
      Path: /
      Method: post

Add a resource to your application

The application template uses AWS Serverless Application Model (AWS SAM) to define application resources. AWS SAM is an extension of AWS CloudFormation with a simpler syntax for configuring common serverless application resources such as functions, triggers, and APIs. For resources not included in the SAM specification, you can use standard AWS CloudFormation resource types.

Fetch, tail, and filter Lambda function logs

To simplify troubleshooting, SAM CLI has a command called sam logs. sam logs lets you fetch logs generated by your deployed Lambda function from the command line. In addition to printing the logs on the terminal, this command has several nifty features to help you quickly find the bug.

NOTE: This command works for all AWS Lambda functions; not just the ones you deploy using SAM.

lambda-gifbot$ sam logs -n GifBotFunction --stack-name lambda-gifbot --tail

You can find more information and examples about filtering Lambda function logs in the SAM CLI Documentation.

Cleanup

To delete the application, use the AWS CLI and run the following:

aws cloudformation delete-stack --stack-name lambda-gifbot

Resources

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 samples and learn how authors developed their applications: AWS Serverless Application Repository main page