go-hello-world-lambda-gateway-cognito

go-hello-world-lambda-gateway-cognito

Simple Go Lambda API Gateway with Cognito Authorization SAM Template Example

Requirements

• AWS CLI already configured with Administrator permission
• Docker installed
• SAM CLI - Install the SAM CLI
• Golang - Currently using v.1.22 (can use Chocolatey or Homebrew)
• Bruno (Optional) - Open source API client. Similar to Postman, but is offline-only and will never require an account.

Local development

1. Build the go executable for the lambda linux environment

   GOARCH=arm64 GOOS=linux go build -o bootstrap main.go
   

2. Zip project (Windows)

   C:\Users\owner\go\bin\build-lambda-zip.exe -o lambda-handler.zip bootstrap using the provided build-lambda-zip package. If needed, you can install with go install github.com/aws/aws-lambda-go/cmd/build-lambda-zip@latest. See To create a .zip deployment package (Windows)

3. Invoke function locally through local API Gateway

   sam.cmd local start-api --template-file=template.yaml
   

   Note: Use sam.cmd when running AWS SAM on windows

   To rebuild and apply local changes, use sam.cmd build --use-container

4. (Optional) Run CRUD Requests Individually

   Can also run CRUD API requests by importing the /bruno collection

Deployment

Ensure you follow the same steps you did to build the executable and zipping the project

1. Build the go executable for the lambda linux environment

   GOARCH=arm64 GOOS=linux go build -o bootstrap main.go
   

2. Zip project (Windows)

   C:\Users\owner\go\bin\build-lambda-zip.exe -o lambda-handler.zip bootstrap using the provided build-lambda-zip package. If needed, you can install with go install github.com/aws/aws-lambda-go/cmd/build-lambda-zip@latest. See To create a .zip deployment package (Windows)

3. Deploy CloudFormation stack template

   sam.cmd deploy --guided --template-file=template.yaml
   

Login

The provided SAM template does not allow any user to sign up. Only designated users in the AWS Cognito Pool can login.

Create Cognito User

1. Login to AWS Console

2. Navigate to CloudFormation

3. Click on this CloudFormation Stack

4. Navigate to Resources

5. Click on UserPool Physical ID Link

6. Click Create User

7. Add User Details and Create User

Login to AWS Cognito

1. Navigate to CloudFormation Stack

2. Navigate to Outputs

3. Click on LoginURL Value

4. Login with Created User Credentials

5. Obtain Access Token

Perform Authorized Request

1. Navigate to CloudFormation Outputs

2. Obtain GatewayAPIEndpoint Value

3. Perform POST Request with Endpoint Value on /Dev/api/any Route with Bearer Token in Authorization Header

4. Verify username and email Values are Present in Response

5. (Optional) Check CloudWatch Logs