A simple HTTP static file server written using nodejs and Python_node.js

In the daily development process, we often need to modify some static files (such as JavaScript, CSS, HTML files, etc.) placed on the CDN. In this process, we hope to have a way to map the online CDN directory to local A directory on the hard disk, so that when we modify a file locally, there is no need to publish it, and the effect can be seen immediately after refreshing.

For example, our CDN domain name is: http://a.mycdn.com, and the corresponding local directory is: D:workassets. We hope that all access to http://a.mycdn.com/* will be mapped Go to the local D:workassets*. For example, when you visit http://a.mycdn.com/s/atp.js, you are actually reading the local D:workassetssatp.js without downloading online files from the Internet.

It is very simple to implement this function, the key points are as follows:

1. Open an HTTP service locally and listen to port 80;
2. Modify the system hosts file, add "127.0.0.1 a.mycdn.com", and bind the CDN domain name to the local server address;
3. Configure the local HTTP service. After receiving a GET request, first check whether the corresponding file exists on the local hard disk. If it exists, the content of the file will be returned. If it does not exist, the corresponding content online will be returned.

As you can see, the key part is to build a local HTTP service. There are many tutorials in this area, such as installing server software such as Apache or Ngnix locally, and then configuring corresponding forwarding rules. However, I personally feel that this method is still a bit complicated. What this article will introduce is another method that does not require the installation of server software.

Because we are developing and debugging locally, the requirements for performance and concurrency are not high, so we actually do not need a professional HTTP software like Apache/Ngnix, we only need a script that can provide HTTP services That’s it. For example, use nodejs to implement it.

Copy code The code is as follows:

/**
 * author: oldj
 *
 **/

var http = require("http"),
url = require("url"),
path = require("path"),
fs = require("fs"),
local_folders,
base_url;

local_folders = [ // Local path, the agent will look for files in the directories in this list, and if not found, go to the online address
"D:/work/assets"
];
base_url = "http://10.232.133.214"; // Online path, if the file cannot be found, redirect to this address

function loadFile(pathname, response) {
var i, l = local_folders.length,
fn;

console.log("try to load " pathname);

for (i = 0; i < l; i ) {

fn = local_folders[i] pathname;
if (path.existsSync(fn) && fs.statSync(fn).isFile()) {
fs.readFile(fn, function (err, data) {
Response.writeHead(200);
Response.write(data);
Response.end();
});

return;
}

}

response.writeHead(302, {
"Location":base_url pathname
});
response.end();
}

http.createServer(
function (request, response) {

var req_url = request.url,
pathname;

// Process requests similar to http://a.tbcdn.cn/??p/global/1.0/global-min.css,tbsp/tbsp.css?t=20110920172000.css
pathname = req_url.indexOf("??") == -1 ? url.parse(request.url).pathname : req_url;
console.log("Request for '" pathname "' received.");
loadFile(pathname, response);

}).listen(80);

Pay attention to modify the values ​​of the local_folders and base_url variables above to the values ​​you need. Save this file, for example, as local-cdn-proxy.js, and then execute "node local-cdn-proxy.js" on the command line. The local server will be running. Of course, don't forget to bind hosts.

When accessing a path through http, the above script will first search in the corresponding local directory. If found, it will return the content of the corresponding file. If it is not found, it will directly 302 jump to the corresponding online address. For situations where it cannot be found, another solution is to have the local server download the corresponding content from online and return it, but for this requirement, a 302 jump is enough.

In addition to the nodejs version, I also wrote a Python version:

Copy code The code is as follows:

# -*- coding: utf-8 -*-
#
# author: oldj
#

import os
import BaseHTTPServer

LOCAL_FOLDERS = [
    "D:/work/assets"
]
BASE_URL = "http://10.232.133.214"

class WebRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):

    def do_GET(self):
        print "Request for '%s' received." % self.path
        for folder in LOCAL_FOLDERS:
            fn = os.path.join(folder, self.path.replace("/", os.sep)[1:])
            if os.path.isfile(fn):
                self.send_response(200)
                self.wfile.write(open(fn, "rb").read())
                break

        else:
            self.send_response(302)
            self.send_header("Location", "%s%s" % (BASE_URL, self.path))

server = BaseHTTPServer.HTTPServer(("0.0.0.0", 80), WebRequestHandler)
server.serve_forever()

可以看到，Python 版本的代码比 nodejs 版本的精简了很多。

上面的两段代码的功能还相对比较简单，比如没有输出内容的 MIME-Type、Content-Length 等头信息，对可能的阻塞操作（如读取文件超时等）也没有做特别的处理。对于本地开发环境来说，它们已经是可以工作的版本了，你也可以继续扩展这两个脚本，以便满足更多的需求。