Use an HTTP trigger to invoke a function

Request struct format

{
    "version": "v1",
    "rawPath": "/example",
    "body": "Hello FC!",
    "isBase64Encoded": false,
    "headers": {
        "header1": "value1",
        "header2": "value1,value2"
    },
    "queryParameters": {
        "parameter1": "value1",
        "parameter2": "value1,value2"
    },
    "requestContext": {
        "accountId": "123456*********",
        "domainName": "<http-trigger-id>.<region-id>.fcapp.run",
        "domainPrefix": "<http-trigger-id>",
        "http": {
            "method": "GET",
            "path": "/example",
            "protocol": "HTTP/1.1",
            "sourceIp": "11.11.11.**",
            "userAgent": "PostmanRuntime/7.32.3"
        },
        "requestId": "1-64f6cd87-*************",
        "time": "2023-09-05T06:41:11Z",
        "timeEpoch": "1693896071895"
    }
}

The following table describes the fields:

Request mapping logic

Function Compute maps incoming HTTP requests to event objects as follows:

• HTTP request headers → event.headers

• Query parameters → event.queryParameters

• Request context information → event.requestContext

• POST request body → event.body

Request mapping examples

curl -v "https://example.cn-hangzhou.fcapp.run?parameter1=value1&parameter2=value2"

curl -v -H "Content-Type: application/json" -d '{"message": "Hello"}' "https://example.cn-hangzhou.fcapp.run"

Response struct format

Your function returns a response struct, which Function Compute parses and maps to an HTTP response:

{
    "statusCode": 200,
    "headers": {
        "Content-Type": "application/json",
        "Custom-Header-1": "Custom Value"
    },
    "isBase64Encoded": false,
    "body": "{\"message\":\"Hello FC!\"}"
}

Response mapping logic

Function Compute maps your function's return value to an HTTP response based on the following rules.

If the function returns valid JSON with a `statusCode` field:

If the function returns valid JSON without a `statusCode`, or non-JSON output:

Function Compute constructs the HTTP response with these defaults:

Response mapping examples

The following table shows how function output is parsed into a response struct and mapped to the HTTP response the client receives.

Base64 decoding

If the function returns valid JSON with isBase64Encoded: true, Function Compute Base64-decodes the body before mapping it to the HTTP response body. If decoding fails, Function Compute returns the raw body value without an error.

HTTP response headers

Function Compute automatically adds the X-Fc-Request-Id response header, which uniquely identifies the request. No other response headers are added automatically.

Custom response headers are supported with the following restrictions:

• Headers starting with X-Fc- are not allowed.

• The following headers are reserved and cannot be overridden: connection, content-length, date, keep-alive, server, content-disposition. If any of these is returned as a custom header, Function Compute ignores it.

Error handling

Error behavior differs depending on how the function is invoked:

• API invocation: Errors are returned in the response body with HTTP status code 200. For example, a Python ModuleNotFoundError returns:

  {
      "errorMessage": "Unable to import module 'index'",
      "errorType": "ImportModuleError",
      "stackTrace": [
          "ModuleNotFoundError: No module named 'not_exist_module'"
      ]
  }

• Function URL invocation: Error details are hidden. Function Compute returns Internal Server Error with HTTP status code 502:

  HTTP/1.1 502 Bad Gateway
  Content-Disposition: attachment
  Content-Type: application/json
  X-Fc-Request-Id: 1-64f6df91-fe144d52e4fd27afe3d8dd6f
  
  Internal Server Error

Use the X-Fc-Request-Id value to look up the full error details in your function's invocation logs.