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Basics

Basics

  • Create & Manage APIs
  • Endpoint for applications
  • Highly available, scalable, handles authentication & authorisation, throttling, caching, CORS, transformations, documentation with OpenAPI, direct integration etc.
  • Public service
  • Can provide HTTP, Rest or Web Sockets end points
  • End point types are
  • Edge Optimized - Incoming requested to nearest CloudFront Point of Presence (POP)
  • Regional Endpoints - Clients from same region can connect
  • Private Endpoints - Accessible only within a VPC through interface endpoint
  • Stages can be used to host different version of the API or to host different environments.
  • Stages can be used for canary deployments. Traffic can be distributed between a main and a canary stage
  • Stage variables can take different values in each Stage
  • APIGateway can import or export Swagger/Open API definition files

Error Codes

  • 4XX Series - Client Error Codes. Something was done wrong by client
  • 400 - Generic Bad Request
  • 403 - Access Denied by Authorizer or WAF filtered the request
  • 429 - API Gateway throttle
  • 5XX Series - Server side error codes. Request was correct but something went wrong on server
  • 502 - Bad gateway exception. Bad response from Lambda or the service
  • 503 - Service is offline
  • 504 - Integration Failure / Timeout of 29s

Caching

  • Caching configured at stage level
  • Cache on a stage can b 500MB to 237GB in size
  • Cache TTL is configurable from min 0 to 3600seconds. Defaul value is 300 seconds
  • Cache can be configured to be encrypted

Integrations

  • Integrations are the backend services that API Gateway exposes as APIs
  • Integrations can be Http Endpoints, Lambda, AWS services like DynamoDB, SNS, SQS, Step Functions
  • The Request phase does Authorization, Validation & Transformation
  • The Response phase does Tranformation, Preparation & Return
  • Proxying does not involve any kind of Transformation. It means straight passthrough of data through API Gateway
  • Types of Integrations include
  • Mocks-Allows API Gateway to return a response itself without invoking any backend service
  • HTTP - Exposes HTTP End Point. Also known as custom HTTP integration
  • HTTP Proxy - Same as HTTP but no transformation is involved
  • AWS - API exposes AWS Services
  • AWS_PROXY(Lambda) - Proxies the request directly to a Lambda
  • AWS & HTTP (non Proxy) integrations use mapping templates.Mapping templates use Velocity Template Language format