quick and dirty node.js maintenance (503 all -- well, almost all) server

maintenance.js

var http = require('http');
var fs = require('fs');

var health_ok_body = "OK\n";
var default_503_body = "Back soon!\n";
var maintenance_file = __dirname + "/maintenance.html";

http.createServer(function (request, response) {
    console.log('request: ' + request.url);

    if (request.url == "/_health") {
        response.writeHead(200, { "Content-Type": "text/plain",
                                  "Content-Length": health_ok_body.length });
        response.end(health_ok_body, "utf-8");
    } else {
        fs.readFile(maintenance_file, function(err, body) {
            var content_type = "text/html";
            if (err) {
                content_type = "text/plain";
                body = default_503_body;
            }
            response.writeHead(503, { "Content-Type": content_type,
                                      "Content-Length": body.length,
                                      "Retry-After": 60 });
            response.end(body, "utf-8");
        });
    }
}).listen(3000, '127.0.0.1');