How to use http module to set proxy server in nodejs

Node.js is a very popular development language, especially in web development. The HTTP protocol is one of the most widely used protocols in web development. In Node.js, use the http module to handle the HTTP protocol.

When developing web applications, we sometimes need to request data from external APIs, but for some reasons we may need to use a proxy server. At this time, we can use the http module of Node.js to set up the proxy server.

This article will introduce how to use the http module to set up a proxy server in Node.js.

Using http proxy

First, we need to start a proxy server. Assume that the proxy server address we start is proxy.example.com and the port number is 8080. Then, in Node.js, we can set the proxy server in the following way:

var http = require('http');
var options = {
  host: 'proxy.example.com',
  port: 8080,
  path: 'http://www.example.com/',
};
var req = http.get(options, function(res) {
  res.setEncoding('utf8');
  res.on('data', function(chunk) {
    console.log(chunk);
  });
});

In the above code, we create an options object to store the address and port number of the proxy server. Then, we send a request using the http.get() method, passing in the options object as a parameter.

In this example, the URL we request is http://www.example.com/. When the proxy server receives the request, it will forward the request to the URL and return the corresponding content. In this example, we set the encoding to utf8 by calling the setEncoding() method of the response object, and then obtain the response data through the data event of the response object.

Use https proxy

In some cases, we need to use https protocol to send requests and need to use a proxy server. In Node.js, we can use https module to handle https protocol.

Similar to http, we can use https proxy server to send https requests. The following is a sample code:

var https = require('https');
var options = {
  host: 'proxy.example.com',
  port: 8080,
  path: 'https://www.example.com/',
};
var req = https.get(options, function(res) {
  res.setEncoding('utf8');
  res.on('data', function(chunk) {
    console.log(chunk);
  });
});

In the above code, we use the https module to send the request and use the options object to set the proxy server address and port number. Then, we send the request using the https.get() method and get the response data through the data event of the response object.

Use exception proxy

In some cases, we want to set the proxy server only for some specific URLs and use the default settings for other URLs. In Node.js, we can use the [tunnel] package to achieve this functionality.

First, we need to install the tunnel package:

npm install tunnel --save

Then, add the following code to your code in order to create the exception proxy:

var HttpsProxyAgent = require('https-proxy-agent');
var HttpsAgent = require('agentkeepalive').HttpsAgent;
var tunnel = require('tunnel');

var url = require('url');

var proxy = 'http://proxy.example.com:8080';
var parsed = url.parse(proxy);

// Create a proxy agent for HTTPS
var agent = tunnel.httpsOverHttp({
  proxy: {
    host: parsed.hostname,
    port: parsed.port,
  },
});

// Set the agent to use the KeepAlive agent to enable HTTP keep-alive
agent = new HttpsAgent({
  keepAlive: true,
  keepAliveMsecs: 3000,
  maxSockets: 10,
  agent: agent,
});

// Set the agent to use the proxy agent for HTTPS requests
var options = url.parse('https://www.example.com');
options.agent = agent;

https.get(options, function(res) {
  res.pipe(process.stdout);
});

In the above code, we create a proxy server and use it for requests to https://www.example.com. First, we use the url module to parse the proxy server URL and create the proxy proxy using the tunnel package. We then set up a KeepAlive agent using the agentkeepalive package to enable the HTTP keep-alive policy. Finally, we use a proxy proxy for HTTPS requests, and the https.get() method sets the proxy options.

Conclusion

In Node.js, it is very common to use the http module to handle the HTTP protocol. When we need to use a proxy server, we can use the above method to set up HTTP and HTTPS proxies. For some specific URLs, we can also use the tunnel package to create exception proxies.

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