Node Microserver

This is an npm package that provides the base functionality for microservers.

This spins up an Express app instance.

Installation

npm install --save microserver

Usage

var MicroServer = require("microserver");
var myService = new MicroServer({ // Argument is optional; defaults are given below
  port: 9876   // What port to listen in on
  handler: function(req,res) { res.status(501).json({working:true}); }, // Express middleware
  mountpoint: "/service", // The endpoint where to mount the handler
  verb: 'all', // Which HTTP method(s) to support: see http://expressjs.com/api.html#app.METHOD
  multerOpts: undefined // File upload control -- see https://github.com/expressjs/multer
});
myService.app // The Express app, for all your customization needs
myService.start();
myService.server // The HTTP server, which exists between "start" and "stop".
myService.stop();

If you don't want the handler to be installed at mountpoint for the verb given in verb, then pass null in as handler.

There is an Express app on the app property of myService. Once you call myService.start(), you can also get a handle on the server under the server property.

The Express app ships with the following bits of middleware installed:

• multer to support multipart file uploads

Configuration Support

The server will use Configise for configuration. The loaded configuration is available under the myService.config property.

Temporary File Support

The server has its own temporary directory named under the myService.tmpDir property. The server will create its temporary files there. If you want its temporary files to go somewhere else, assign this property. However, if you reassign this property, you are taking responsibility for ensuring that the directory exists and cleaning up the directory when done. (The server will provide and clean up the default directory for you.)

If you want to create a subdirectory in the temp dir, use myService.tmpSubdir('my-subdir'). This will create a folder named 'my-subdir' within the temporary directory folder. Currently, only one layer of temporary directories are allowed.

If you want access to a file, call myService.withTempFie(prefix, suffix, cb). The final argument (cb) is a callback that will get two arguments: the temporary file descriptor and then the path to the temporary file. The callback is expected to return a value, a Promise, or a Thenable (see the Bluebird API for resolve). When that resolves, the temporary file will be deleted.

Promise.promisifyAll(fs);

myService.withTempFile("foo", null, function(fd, filePath) {
  var buffer = new Buffer("Hello, World!");
  return fd.writeAsync(fd, buffer, 0, buffer.length, null).tap(function() {
    console.log("Wrote the buffer out to " + filePath + " => " + fs.readFileSync(filePath));
  });
});

For More Details

See the tests under ./test.

Note

This class would inherit from the Express Application class, enabling you to manipulate the express app without having to do .app, except there is no such class. Our hacky efforts based on manipulating __proto__ or prototype have proved fruitless, but we would welcome a pull request.

Provided Functionality

Aside from making your code much more concise and readable, this class also provides some useful utility methods for monitoring the microservice.

GET /health

Provides information derived from os and process modules. If you want to customize/override the information provided, then override the healthCheck method: the response from /health is the JSON of the return value from the healthCheck method.

The default implementation provides a few fields:

• load -- The average CPU load on the server, provided in the fields 1min, 5min, and 15min for the last 1 minute, 5 minutes, and 15 minutes. These values come from os.loadavg(), except they are scaled by CPU count, so they are always between 0 and 1.
• cpus -- The count of CPUs.
• uptime -- The time (in seconds) that the process has been up.
• memory -- The memory profile of the system. The fields are free (free memory on the system), total (total memory on the system), load (free memory divided by total memory), and process (the resident memory set size of the process).

In addition to the diagnostic information, this also can work as a rudimentary performance check, since it does make some basic system calls.

GET /ping

Simply returns {pong:true}. If you want to customize that value, override the ping method: the response from /ping is the JSON of the return value from the ping method. This is intended as an absolute minimal check of performance.

TODO

• Add logging.
• Add the ability to do HTTP BASIC auth with a username/password stored in Configise.
• Add a body parser for JSON