AWS Solutions Architect Project (Performance Efficiency Pillar) – Serverless Application – Part 4

In this part, we are going to expose our Lambda functions via API gateway as REST endpoints to allow external applications interact via HTTP requests. In essence, API gateway is the main door for our serverless endpoints while it provides unified interface for all API requests and security with its built-in authentication, authorization, and rate limiting.

Step 1: Setup API Gateway

• Visit API Gateway console
• Click Create API
• Select HTTP API, click Build
  • Configure API Details
    • API Name: ProductInventory
    • IP Address Type: IPv4
  • Left the rest options (i.e. stage and CORS) as default
  • Click Create

Step 2: Setup Routes and Integrations

Routes define the URL paths and HTTP methods that our API accepts. In the meantime, integrations connect routes to our Lambda functions

GET Routes Setup (READ)

Route 1: GET all products

• Click Create Route
• Method: GET
• Resource Path: /product
• Purpose: Retrieve all product items from inventory
• Click Create

Route 2: GET specific product

• Click Create Route
• Method: GET
• Resource Path: /product/{id}
• Purpose: Retrieve specific product item by ID
• {id}: Path parameter that will be passed to Lambda function
• Click Create

Setup Integrations for Both of GET Routes Above

• Go to Integrations, select Manage Integrations, and click Create
• Attach to Route: GET /product
• Integration Target: Lambda function
• Lambda Function: Select getProduct
• Set Invoke Permissions
  • Invoke Permissions: Keep enabled
  • This grants API Gateway permission to invoke our Lambda function while creates the necessary IAM permissions automatically
• Click Create

Now let’s test the endpoint by going to the APIs menu from the sidebar, and choose generated API.

• Copy the invoked URL
• Go to new window/tab and paste the invoked URL before adding /product the the end of it

Then it shall return the data in JSON format

Finally, we need to attach the 2nd GET route to the integration

• Go back to Routes → Select /product/{id} → Attach Integration
• Choose existing integration: getProduct
• Click Attach Integration

PUT Route Setup (UPDATE)

• Go to API Gateway, select Routes, click Create Route
• Method: PUT
• Resource Path: /product/{id}
• Purpose: Update specific product item by ID
• Click Create

Setup Integrations for PUT Route

• Go to Integrations, select Manage Integrations, and click Create
• Attach to Route: PUT /product/{id}
• Integration Target: Lambda function
• Lambda Function: Select updateProduct
• Set Invoke Permissions
  • Invoke Permissions: Keep enabled
  • This grants API Gateway permission to invoke our Lambda function while creates the necessary IAM permissions automatically
• Click Create

DELETE Route Setup (DELETE)

• Go to API Gateway, select Routes, click Create Route
• Method: DELETE
• Resource Path: /product/{id}
• Purpose: Delete specific product item by ID
• Click Create

Setup Integrations for DELETE Route

• Go to Integrations, select Manage Integrations, and click Create
• Attach to Route: DELETE /product/{id}
• Integration Target: Lambda function
• Lambda Function: Select deleteProduct
• Set Invoke Permissions
  • Invoke Permissions: Keep enabled
  • This grants API Gateway permission to invoke our Lambda function while creates the necessary IAM permissions automatically
• Click Create

POST Route Setup (CREATE)

• Go to API Gateway, select Routes, click Create Route
• Method: POST
• Resource Path: /product
• Purpose: Delete specific product item by ID
• Click Create

Setup Integrations for POST Route

• Go to Integrations, select Manage Integrations, and click Create
• Attach to Route: POST /product
• Integration Target: Lambda function
• Lambda Function: Select addProduct
• Set Invoke Permissions
  • Invoke Permissions: Keep enabled
  • This grants API Gateway permission to invoke our Lambda function while creates the necessary IAM permissions automatically
• Click Create

API Routes Summary

So far our API routes should be similar with something like this:

HTTP Methods	Route Paths	Lambda Functions	Operations
GET	/product	getProduct	Get all products
GET	/product/{id}	getProduct	Get specific product
PUT	/product/{id}	updateProduct	Update existing product
DELETE	/product/{id}	deleteProduct	Delete specific product
POST	/product	addProduct	Create new product

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Summary

In this part we have been applying some best practices in setting up Lambda function and security around of it. We have applied RESTful API design based on the CRUD operations with such clear and consistent URL naming with its respective parameter. We also have setup the automatic IAM role for API gateway and also the principle of least privilege so that each integration only has permission to invoke it specific Lambda function.

In the next part, we will develop front-end part via AWS Amplify, test all API endpoints, set error handling, configure CORS, and setup the monitoring and logging.