APIG Event Source

API Gateway (APIG) is an API hosting service that helps enterprises to build, manage, and deploy APIs at any scale. With APIG, your function can be invoked through HTTPS by using a custom REST API and a specified backend. You can map each API operation (such as, GET and PUT) to a specific function. APIG invokes the relevant function when an HTTPS request is sent to the API backend.

For more information about how to use HTTPS calls to trigger functions, see Using an APIG (Dedicated) trigger.

Example APIG Event

apig_base64_event.json

{
  "body": "eyJuYW1lIjogIk9wZW5UZWxla29tQ2xvdWQifQ==",
  "requestContext": {
      "apiId": "bc1dcffd-aa35-474d-897c-d53425a4c08e",
      "requestId": "11cdcdcf33949dc6d722640a13091c77",
      "stage": "RELEASE"
  },
  "queryStringParameters": {
      "responseType": "html"
  },
  "httpMethod": "GET",
  "pathParameters": {},
  "headers": {
      "accept-language": "q=0.5,en-US;q=0.3,en;q=0.2",
      "accept-encoding": "gzip, deflate, br",
      "x-forwarded-port": "443",
      "x-forwarded-for": "103.218.216.98",
      "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
      "upgrade-insecure-requests": "1",
      "host": "host",
      "x-forwarded-proto": "https",
      "pragma": "no-cache",
      "cache-control": "no-cache",
      "x-real-ip": "103.218.216.98",
      "user-agent": "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0"
  },
  "path": "/",
  "isBase64Encoded": true
}

Parameter description

Parameter	Type	Description
body	String	Actual request body in string format (Base64 encoded).
requestContext	Map	Request information, including the API gateway configuration, request ID, authentication information, and source.
httpMethod	String	HTTP method
queryStringParameters	Map	Query strings configured in APIG and their actual values
pathParameters	Map	Path parameters configured in APIG and their actual values
headers	Map	Complete headers
path	String	Complete path
isBase64Encoded	Boolean	Default value: true (see Notes below)

Notes

• When calling a function using APIG, isBase64Encoded is valued true by default, indicating that the request body transferred to FunctionGraph is encoded using Base64 and must be decoded for processing.

• The function must return characters strings by using the following structure.

  {
    "isBase64Encoded": "true|false",
    "statusCode": "httpStatusCode",
    "headers": {"headerName":"headerValue"},
    "body": "..."
  }
  

Note

For asynchronous invocation, of FunctionGraph, select the APIG trigger and click its name to go to the APIG console, and select Asynchronous for the Invocation Mode. For details, see

• Asynchronous Invocation in user manual and

• Configuring Backend Settings in API gateway user manual

Example

index.py

import json

from fg_apig_event import APIGEvent, APIGResponse


def handler(event, context):
  logger = context.getLogger()

  logger.info("Function Name: %s", context.getFunctionName())

  apig_event = APIGEvent(event)
  is_base64_encoded = apig_event.is_base64_encoded() or False

  body = apig_event.get_body()
  logger.info("APIG Event body: %s", body)

  response_type = apig_event.get_query_string_parameter("responseType")

  if response_type == "html":
    output = APIGResponse(
      200,
      "",
      {"Content-Type": "text/html; charset=utf-8"},
      False,
    )
    output.set_body(
      "<html><h1>Welcome to use FunctionGraph</h1></html>",
      is_base64_encoded,
    )
  elif response_type == "json":
    output = APIGResponse(
      200,
      "",
      {"Content-Type": "application/json"},
      False,
    )
    try:
      parsed_body = json.loads((body or "").replace('\\"', '"'))
      output.set_body(parsed_body, is_base64_encoded)
    except (json.JSONDecodeError, TypeError):
      output.set_body({"error": "Invalid JSON input"}, is_base64_encoded)
  else:
    output = APIGResponse(
      200,
      "",
      {"Content-Type": "text/html; charset=utf-8"},
      False,
    )
    output.set_body(
      "<html>Please construct the url with query parameters responseType=html, responseType=json</html>",
      is_base64_encoded,
    )

  logger.info("returning: %s", output)

  return output

Full sample code is available in the samples-doc/scratch-event-apig.

Package description

Public package exports for fg_apig_event.

class fg_apig_event.APIGEvent(event)

Bases: object

Represents an API Gateway event for FunctionGraph.

Attributes:

• body (str): The request body

• isBase64Encoded (bool): Whether the body is base64 encoded

• requestContext (dict): Request context information

• queryStringParameters (dict): Query string parameters

• httpMethod (str): HTTP method

• pathParameters (dict): Path parameters

• headers (dict): Request headers

• path (str): Request path

Initialize APIGEvent.

Args:

event (dict): The API Gateway event data

get_body()

Returns the decoded request body.

Returns:

str: Body content in plain text

get_raw_body()

Returns the raw request body.

Returns:

str: Body content as received

get_request_context()

Returns the request context.

Returns:

APIGRequestContext: The request context object

get_request_context_value(key)

Get a value from the request context by key.

Args:

key (str): The key to retrieve

Returns:

str: The value or empty string if not found

get_query_string_parameters()

Returns the query string parameters.

Returns:

dict: Query string parameters

get_query_string_parameter(param_name)

Get a query string parameter by name.

Args:

param_name (str): The parameter name

Returns:

str: The parameter value or empty string if not found

get_http_method()

Returns the HTTP method.

Returns:

str: The HTTP method

get_path_parameters()

Returns the path parameters.

Returns:

dict: Path parameters

get_path_parameter(param_name)

Get a path parameter by name.

Args:

param_name (str): The parameter name

Returns:

str: The parameter value or empty string if not found

get_headers()

Returns the request headers.

Returns:

dict: Request headers

get_header(header_name)

Get a header value by name.

Args:

header_name (str): The header name

Returns:

str: The header value or empty string if not found

get_path()

Returns the request path.

Returns:

str: The request path

is_base64_encoded()

Returns whether the body is base64 encoded.

Returns:

bool: True if base64 encoded, False otherwise

to_json()

Returns the event as a dictionary.

Returns:

dict: The raw event data

class fg_apig_event.APIGRequestContext(request_context)

Bases: object

Represents the request context of an API Gateway event.

Attributes:

apiId (str): The API ID requestId (str): The request ID stage (str): The stage

Initialize APIGRequestContext.

Args:

request_context (dict): The request context data

get_api_id()

Returns the API ID.

Returns:

str: The API ID

get_request_id()

Returns the request ID.

Returns:

str: The request ID

get_stage()

Returns the stage.

Returns:

str: The stage

get_value(key)

Get a value from the request context by key.

Args:

key (str): The key to retrieve

Returns:

str: The value or None if not found

to_json()

Returns the request context as a dictionary.

Returns:

dict: The raw request context data

class fg_apig_event.APIGResponse(status_code=200, body='', headers=None, is_base64_encoded=False)

Bases: object

Represents an API Gateway response for FunctionGraph.

Attributes:

statusCode (int): HTTP status code body (str): Response body headers (dict): Response headers isBase64Encoded (bool): Whether the body is base64 encoded

Initialize APIGResponse.

Args:

status_code (int, optional): HTTP status code. Defaults to 200. body (str, optional): Response body. Defaults to “”. headers (dict, optional): Response headers. Defaults to {}. is_base64_encoded (bool, optional): Whether body is base64 encoded. Defaults to False.

classmethod from_json(data)

Create an APIGResponse from a dictionary.

Args:

data (dict): Dictionary with response data

Returns:

APIGResponse: A new APIGResponse instance

set_status_code(status_code)

Set the HTTP status code.

Args:

status_code (int): The HTTP status code

set_body(body, is_base64_encoded=False)

Set the response body.

Args:

body (str or dict): The body content is_base64_encoded (bool, optional): Whether to encode as base64. Defaults to False.

get_raw_body()

Returns the raw response body.

Returns:

str: The body as stored

get_body()

Returns the decoded response body.

Returns:

str: The body content in plain text

get_body_parsed()

Returns the parsed response body as a Python object.

Returns:

dict or str or None: The parsed body content

to_json()

Returns the response as a dictionary.

Returns:

dict: The response data

last updated: 2026-09-30 08:01:05 UTC - commit: 9655e588c27eff2dd2f5891bc87fe541f6458b7d