Skip to main content
  1. Projects/
  2. AWS DevOps Pro Certification/
  3. 2: Configuration Mgmt / Infrastructure as Code/
  4. 1: Lambda/

4: API Gateway

·1 min

What is API Gateway?

  • Make your own REST or websocket APIs
  • Connect programmers (via HTTP GET and POST requests) to:
    • Lambdas
    • DynamoDB
    • Ec2
    • S3
    • Caches
    • Cloudwatch
    • Etc.

REST vs Websockets?

  • REST: 1-way comms; simple request/response
  • Socket: 2-way comms; e.g. update the GUI as we go
    • Backend service can initiate comms
    • Real-time chat is one good example


  • Web identity federation stuff

What about HTTP APIs?

  • Cheaper and faster than REST
  • Still lacking full functionality of REST
  • Go with HTTP unless you need those extra functionalities

What’s Lambda Proxy Integration?

  • You can proxy requests as-is to lambda funcs
  • You can point API Gateway to lambda aliases
    • E.g. point to “prod” rather than “version 2”
  • You have to give API gateway permission to invoke a lambda function
    • The function has a resource-based policy to allow this

How is the API updated automatically?

  • When you add an API to your function—
    • …via lambda console,
    • …via API gateway console,
    • …or via SAM template,
  • The resource-based policy is updated automatically.