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DocumentationAPI GatewayPlugin UsageCustom Request Body
Custom Request Body
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Last updated: 2023-12-22 10:01:48
Custom Request Body
Last updated: 2023-12-22 10:01:48
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Overview

The request body sent to service backend by the Client contains many fields. If you want to modify the content of the request body, you can do so via custom request body plugin.
The custom request body plugin applies during the request process. The request body rewriting service can be deployed in SCF, on the public network, or in a VPC. API Gateway will forward the request content to the request body rewriting service after receiving it from the client. The rewriting service will send the content of the request body to API Gateway after modifying it. Then, API Gateway will forward the modified request body to the service backend.




Prerequisites

For verification services deployed in SCF, you need to enable the SCF service.

Directions

Step 1. Create a function to modify the request body

For verification functions deployed on the public network or in a VPC, you can skip this step.
1. Log in to the SCF console.
2. Click Functions on the left sidebar to enter the function list page.
3. Click Create at the upper-left corner of the page to create a SCF that is used to modify the request body.

Step 2. Create a custom request body plugin

1. Log in to the API Gateway console.
2. On the left sidebar, click Plugin > Custom Plugin to enter the custom plugin list page.
3. Click Create in the top-left corner of the page to create a custom request body plugin.
For verification services deployed in SCF, you need to enter the following data when creating the custom request body plugin:
Parameter
Required
Description
Function
Yes
Select the namespace, name, and version of the function that is used to modify the request body.
Backend timeout
Yes
Set the backend timeout that API Gateway forwards the request to the function that is used to modify the request body. The maximum time limit is 30 minutes. When no response is returned before the timeout after API Gateway calls the function, API Gateway will end the call and return an error message.
Custom content
Yes
Set the request content sent by API Gateway to the function used to modify the request body. You can select Header, Body, and Query. The request content not selected will not be modified and will be forwarded to the service backend as is.
Base64 Encoding
Yes
Specify whether to forward the request content to the function after applying Base64 encoding. Generally, it is applicable to binary content.
For verification services deployed on the public network, you need to enter the following data when creating the custom verification plugin:
Parameter
Required
Description
Request method
Yes
Request method of the custom request body function, which can be GET, POST, PUT, DELETE, HEAD, and ANY.
Public network service
Yes
Access address of the request body service, which can be an HTTP or HTTPS address.
Path match mode
Yes
It can be backend path or full path match.
Backend path match: The configured path is used to request the service.
Full path match: The overlapping part is used to request the service. For example, if the configured API path is `/a/` and the request path is `/a/b`, then the path transferred to the service will be `/b` after full path match is enabled.
For verification services deployed in a VPC, you need to enter the following data when creating the custom verification plugin:
Parameter
Required
Description
VPC
Yes
Select the VPC of the custom request rewriting service.
Request method
Yes
Request method of the custom request rewriting service, which can be GET, POST, PUT, DELETE, HEAD, and ANY.
Backend address
Yes
Access address of the custom request body service, which can be an HTTP or HTTPS address.

Step 3. Bind the API

1. Select the plugin created in step 2 from the list. Click Bind API in the Operation column.
2. In the Bind API pop-up window, select the service, environment, and the target API.
3. Click OK to bind the plugin to the API. At this time, the configuration of the plugin has taken effect for the API.

How to Write Custom Request Body Function

Returned value definition

The custom request body plugin of API Gateway needs to receive the response in a certain format returned by the custom request body SCF. The specific format is as follows:
{
  "replace_headers":{
    "header1":"header1-value",
    "header2":"header2-value"
  },
  "remove_headers":[
    "header3",
    "header4"
  ],
  "replace_body":"hello",
  "replace_querys":{
    "query1":"query1-value",
    "query2":"query2-value"
  },
  "remove_querys":[
    "query3",
    "query4"
  ]
}

Demo for Python

For more information on how to write the function that is used to modify the request body in Python, see Custom Request Body Demo for Python.

Demo for Java

package com.example.demo;

import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.qcloud.services.scf.runtime.events.APIGatewayProxyRequestEvent;

public class Demo {

    public String mainHandler(APIGatewayProxyRequestEvent request) {
        System.out.println("helloworld");
        System.out.println(request.getHttpMethod());
        JsonObject resp = new JsonObject();
        headerHandler(request, resp);
        headerQuery(request, resp);
        headerBody(request, resp);
        return resp.toString();
    }

    private void headerHandler(APIGatewayProxyRequestEvent request, JsonObject resp) {
        JsonObject replace_headers = new JsonObject();
        JsonArray remove_headers = new JsonArray();
        // Sample: Replace or add `header1` and `header2`
        replace_headers.addProperty("header1", "header1-value");
        replace_headers.addProperty("header2", "header2-value");

        // Sample: Delete `query3`
        remove_headers.add("header3");
        resp.add("replace_headers", replace_headers);
        resp.add("remove_headers", remove_headers);
    }

    private void headerQuery(APIGatewayProxyRequestEvent request, JsonObject resp) {
        JsonObject replace_querys = new JsonObject();
        JsonArray remove_querys = new JsonArray();

        // Sample: Replace or add `query1` and `query2`
        replace_querys.addProperty("query1", "query1-value");
        replace_querys.addProperty("query2", "query2-value");

        // Sample: Delete `query3`
        remove_querys.add("query3");
        resp.add("replace_querys", replace_querys);
        resp.add("remove_querys", remove_querys);
    }

    private void headerBody(APIGatewayProxyRequestEvent request, JsonObject resp) {
        resp.addProperty("replace_body", "{'name':'Yagr'}");
    }
}

PluginData

{
    "endpoint_timeout":15, // Backend timeout period in seconds. Value range: 0–60
    "func_name":"test_name", // Custom SCF name
    "func_namespace":"test_namespace", // Custom SCF namespace
    "func_qualifier":"$LATEST", // Custom SCF version
    "is_base64_encoded":true, // Whether to forward the request content to the SCF after applying Base64 encoding
    "is_send_req_body":true, // Whether to send the request Body content to the SCF
    "is_send_req_headers":true, // Whether to send the request Header content to the SCF
    "is_send_req_querys":true, // Whether to send the request Query content to the SCF
    "user_id":1253970226 // appid
}

Notes

Binding a custom plugin to the API means creating a trigger for the SCF to trigger the API. Deleting the trigger on the SCF side means unbinding the plugin from the API.
For now, the custom request body plugin only supports event-triggered function and does not support HTTP-triggered function.
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