Are Client SDKs Available for FastProxy? A Complete Guide to the Go SDK

FastProxy provides a native Go client SDK that allows applications to integrate directly with the proxy using first-class APIs from the github.com/Kingson4Wu/fast_proxy module.

The kingson4wu/fast_proxy repository ships with a built-in client SDK designed specifically for Go applications. Unlike standalone proxy servers that require manual HTTP configuration, this SDK provides ready-to-use helpers for building HTTP clients, attaching required service-name headers, and invoking proxy entry points with automatic retry policies and connection pooling.

What Is the FastProxy Client SDK?

The FastProxy client SDK is a collection of Go packages within the main module that handle the client-side logic for communicating with FastProxy gateways. According to the repository's README.md, the SDK offers "first-class APIs for integrating FastProxy directly into Go applications"【/tmp/instagit_aexrechr/README.md†L44-L48】.

The architecture documentation in documentation/website/docs/intro.md reinforces this, listing the client SDK as a core building block alongside the in-proxy and out-proxy components【/tmp/instagit_aexrechr/documentation/website/docs/intro.md†L66-L71】.

Core Components

The SDK spans several packages:

• inproxy – Contains the server bootstrap logic and client configuration
• inproxy/internal/proxy – Houses httpclientProxy.go, which implements the BuildClient function for configuring HTTP clients with retry logic and header filtering
• outproxy/internal/proxy – Mirrors the client-side logic for outbound proxy connections

How to Use the FastProxy Go SDK

Installation

Import the module directly into your Go project:

go get github.com/Kingson4Wu/fast_proxy

Making Your First Request

The examples/client/client.go file demonstrates minimal SDK usage【/tmp/instagit_aexrechr/examples/client/client.go†L12-L27】【/tmp/instagit_aexrechr/examples/client/client.go†L50-L68】:

package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"strings"

	"github.com/Kingson4Wu/fast_proxy/examples/center"
)

func main() {
	// Call downstream services via the FastProxy gateway
	send("song_service", "token_service")
	send("chat_service", "search_service")
}

func send(clientName, destServiceName string) {
	// Build request payload
	body := strings.NewReader(fmt.Sprintf("param=%s", "hello"))

	// Resolve proxy address via the Center component
	proxyURL := fmt.Sprintf("http://%s/%s/api/service",
		center.GetAddress("out_proxy"), destServiceName)

	req, err := http.NewRequest("POST", proxyURL, body)
	if err != nil {
		log.Fatalf("request build error: %v", err)
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	
	// Required header that identifies the caller to FastProxy
	req.Header.Set("C_ServiceName", clientName)

	// Execute request
	resp, err := (&http.Client{}).Do(req)
	if err != nil {
		log.Fatalf("request error: %v", err)
	}
	defer resp.Body.Close()

	log.Printf("response status: %d", resp.StatusCode)
	b, _ := io.ReadAll(resp.Body)
	log.Println(string(b))
}

Configuring the HTTP Client

For production use, leverage the SDK's BuildClient function located in inproxy/internal/proxy/httpclientProxy.go. This helper configures connection pooling, hop-by-hop header filtering, and retry policies.

The function is invoked during server initialization in inproxy/inproxy.go:

// From inproxy/inproxy.go
func NewServer(config Config) (*Server, error) {
	// BuildClient configures the HTTP client with FastProxy-specific settings
	client := proxy.BuildClient(config)
	// ... server initialization continues
}

To use the configured client in your application:

import "github.com/Kingson4Wu/fast_proxy/inproxy/internal/proxy"

// Build a client with retry logic and header filtering
client := proxy.BuildClient(config)

// Use the client for proxy requests
resp, err := client.Do(request)

Key Features of the FastProxy Client SDK

The Go SDK provides several production-ready capabilities:

• Automatic Header Management – Automatically attaches the C_ServiceName header required for service identification
• Retry Policies – Built-in exponential backoff and retry logic for failed requests
• Connection Pooling – Optimized HTTP client configuration for high-throughput scenarios
• Hop-by-Hop Header Filtering – Automatic removal of headers that should not be forwarded through proxies (implemented in httpclientProxy.go)

Summary

• FastProxy provides a native Go client SDK as part of the github.com/Kingson4Wu/fast_proxy module
• The SDK includes helper functions in inproxy/internal/proxy/httpclientProxy.go for building configured HTTP clients
• Use the C_ServiceName header to identify your service when making requests through the proxy
• Reference implementation examples are available in examples/client/client.go
• The BuildClient function handles retry policies, connection pooling, and header filtering automatically

Frequently Asked Questions

Is there a JavaScript or Python SDK for FastProxy?

Currently, FastProxy only provides an official client SDK for Go. The repository contains no JavaScript, Python, or other language bindings. However, since FastProxy communicates over standard HTTP, you can interact with it from any language by manually setting the required C_ServiceName header and following the proxy protocol outlined in the documentation.

How do I set the required service name header?

You must set the C_ServiceName header on every request to identify your client to the proxy. In Go, use req.Header.Set("C_ServiceName", "your_service_name") before sending the request. The examples/client/client.go file demonstrates this pattern, showing how the header value is passed as the clientName parameter in the send function.

Can I customize retry policies in the Go SDK?

Yes, the SDK's BuildClient function in inproxy/internal/proxy/httpclientProxy.go configures the HTTP client with retry logic. While the repository provides sensible defaults for connection pooling and header filtering, you can examine the BuildClient implementation to understand the configuration structure. For advanced customization, you may need to fork or wrap the existing client builder with your own retry middleware.

Where is the BuildClient function defined?

The BuildClient function is defined in inproxy/internal/proxy/httpclientProxy.go. This function is responsible for constructing an http.Client configured with FastProxy-specific settings including hop-by-hop header filtering, retry policies, and connection pooling. It is invoked during server initialization in inproxy/inproxy.go to prepare the client used for proxy communications.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}