Hacks to get Loopback App’s running on Heroku

To get Loopback App’s running on Heroku, a couple of hacks are required due to the way Loopback manages it’s configurations.

The first issue to solve is to get Loopback to take the port number from the environment since Heroku uses arbitrary port numbers to target different applications.

There is probably a more elegant way, however I first wanted to stay out of node_modules files, so I opted to just focus on modifying server.js.

It’s actually very easy, since loopback internally supports passing arguments to the listen function all the way out from the server.js file.
It does this by switching between automatic configuration and explicit configuration from the arguments passed to the listen function.

So, basically it’s just amending the “start” function to fetch the port number from the environment and pass it as argument to the listen function.

I have done it this way…

app.start = function () {
   // start the web server
   var port = process.env.PORT || 8000;
   return app.listen(port, function () {
      console.log('Web server listening at: %s', app.get('url'));

Using node-sass with latest version of io.js

When using node-sass together with io.js, one of the problems is that it’s not updated to work with the latest version of io.js (at the time of writing, v.1.6.2).
Currently node-sass only supports io.js until v.1.2.

This causes the installation of node-sass and any libraries that depends on node-sass to fail to fetch all resources during installation, which eventually causes processes that tries to use the node-sass library to fail.

The error message during installation is (in my case, using io.js 1.6 on a MBP) the following:

Can not download file from https://raw.githubusercontent.com/sass/node-sass-binaries/v2.0.1/darwin-x64-iojs-1.6/binding.node

The error message in the process trying to use node-sass:

Error: `libsass` bindings not found. Try reinstalling `node-sass`?

The failing part is when the node-sass library tries to fetch binding files which are necessary to connect to some of it’s libraries, the solution is therefore to either change the code where it fails (easy, but messy, not my recommendation) or simply download the binding files and manually add it to node-sass (easy, and also a bit messy, but at least we don’t change the code, so a bit easier to manage).

So, what I did, downloaded the file from here:

and save it to the following location:

Now, when you execute a process that uses node-sass, it will find the file, and even you are not running io.js 1.2, the binding still works (only tried with io.js 1.6).

It’s by no means a perfect solution, but it solves the problem immediately and it’s something easily automated since it only involves downloading and copying some files, not changing some code…