CORS Configuration

This section explains how to configure CORS (Cross-Origin Resource Sharing) using environment variables only.

Avoid hardcoding CORS values inside functions or configuration files.

{
  "allowOrigins": [],
  "allowMethods": []
}

Step 1: Define CORS in Environment Files

Add CORS as a JSON string in your environment files.

CORS={"allowOrigins":["localhost","example.com"],"allowMethods":["GET","POST","PUT","DELETE","OPTIONS"]}

Step 2: Pass CORS via Function Config

Always inject CORS from environment into the function configuration.

environmentVariable: {
"cors": "${env.CORS}"
}

Step 3: Use CORS in Handler

Parse the CORS config from process.env and apply it to response headers.

const cors = JSON.parse(process.env.cors as string);

headers: {
    "Access-Control-Allow-Origin": cors.allowOrigins.join(','),
    "Access-Control-Allow-Methods": cors.allowMethods.join(','),
}