Connecting Lambda to API Gateway
Overview
Domain expertise for creating Amazon API Gateway REST APIs and connecting them to existing Lambda functions. Covers API creation, resource and method setup, Lambda proxy integration, CORS configuration, security controls, deployment, and testing.
Connect a Lambda function to API Gateway
To create a REST API and wire it to a Lambda function, follow the procedure exactly. See Lambda to API Gateway connection procedure [blocked].
The procedure supports configurable authorization types (NONE, AWS_IAM, COGNITO_USER_POOLS, CUSTOM), optional API key requirements, CORS setup, and production security hardening including throttling and access logging.
Troubleshooting
502 Bad Gateway
The Lambda function must return a proxy-compatible response with statusCode,
headers, and a stringified body. See the full procedure for format details.
Permission denied invoking Lambda
Ensure lambda:InvokeFunction permission was added with the correct API Gateway
source ARN. See the full procedure for details.
CORS errors in browser
Verify enable_cors was set to true, the OPTIONS method was created, and CORS
headers are configured in both method and integration responses.
