hw-lambda-api

Example of creating and deploying an API with Lambda and Terraform on AWS

Prerequisites

• Install Terraform
• Install the AWS CLI
• Log into your dev account (with aws sso login)
• Ensure your account has a Terraform State S3 Backend deployed
• If you're outside the byu-oit GitHub organization:
  • Obtain a DivvyCloud username and password from the Cloud Office at cloudoffice@byu.edu
  • Install the GitHub App used for auto-merging Dependabot pull requests to your organization

Setup

• Create a new repo using this template.

  You need your own repo so that you can push changes and have GitHub Actions deploy them.

  Keep your repo name relatively short. Since we're creating AWS resources based off the name, we've seen issues with repo names longer than about 24 characters.

• Clone your new repo

git clone https://github.com/byu-oit/my-new-repo

• Check out the dev branch

cd my-new-repo
git checkout -b dev

• Find and replace across the repo:
  • replace 977306314792 with your dev AWS account number
  • replace 539738229445 with your prd AWS account number
  • replace hw-lambda-api with the name of your repo
  • replace byu-oit-terraform-dev with the name of your dev AWS account
  • replace byu-oit-terraform-prd with the name of your prd AWS account
  • replace Codepipeline-Standard-Change with your Standard Change Template ID - If you need to create a new template, ask in #servicenow for help getting it into the sandbox ServiceNow environment
• Rename .postman/hw-lambda-api.postman_collection.json with the name of your repo replacing hw-lambda-api in the filename
• Add yourself (or your team) as a Dependabot reviewer in dependabot.yml
• Enable Dependabot Security updates if you're outside the byu-oit GitHub organization
• Commit your changes

git commit -am "Update template with repo specific details" 

Deployment

Deploy the "one time setup" resources

cd terraform-iac/dev/setup/
terraform init
terraform apply

In the AWS Console, see if you can find the resources from setup.tf (SSM Param).

Push your changes

git push -u origin dev

If you look at .github/workflows/deploy.yml, you'll see that it is set up to run on pushes to the dev branch. Because you have already pushed to the dev branch, this workflow should be running now.

• In GitHub, click on the workflow run (it has the same name as the last commit message you pushed)
• Click on the Build and Deploy job
• Expand any of the steps to see what they are doing

View the deployed application

Anytime after the Terraform Apply step succeeds:

cd ../app/
terraform init
terraform output

This will output a DNS Name. Enter this in a browser. You should get a JSON response. Between index.js and main.tf, can you find what pieces are necessary to make this data available to the app?

In the AWS Console, see if you can find the other resources from main.tf.

Push a change to your application

Make a small change to index.js (try adding a console.log, a simple key/value pair to the JSON response, or a new path). Commit and push this change to the dev branch.

git commit -am "try deploying a change"
git push

In GitHub Actions, watch the deploy steps run (you have a new push, so you'll have to go back and select the new workflow run instance and the job again). Once it gets to the CodeDeploy step, you can watch the deploy happen in the CodeDeploy console in AWS. Once CodeDeploy says that production traffic has been switched over, hit your application in the browser and see if your change worked. If the service is broken, look at you Lambda logs in CloudWatch to see if you can figure out why.

Note:

It's always best to test your changes locally before pushing to GitHub and AWS. Testing locally will significantly increase your productivity as you won't be constantly waiting for GitHub Actions and CodeDeploy to deploy, just to discover bugs.

You can either test locally inside Docker, or with Node directly on your computer. Whichever method you choose, you'll have to setup any environment variables that your code is expecting when it runs in AWS. You can find these environment variables in index.js and main.tf. You'll also have to provide an alternate way of serving your API. Fronting the API code with an express app is a common pattern for local development. Then switching to using the Lambda Handler when deployed in AWS.

Learn what was built

By digging through the .tf files, you'll see what resources are being created. You should spend some time searching through the AWS Console for each of these resources. The goal is to start making connections between the Terraform syntax and the actual AWS resources that are created.

Several OIT created Terraform modules are used. You can look these modules up in our GitHub Organization. There you can see what resources each of these modules creates. You can look those up in the AWS Console too.