How can I set up a node app (ember app kit) on heroku that reads ENV variables and makes the values available to the application?

Question

Okay, I'm new to node, and really only just using the node server to serve static js, but I can't find any info on this anywhere.

I'm running an application ember app kit, which gets built to a node server.js for deploy, and heroku runs it with node server.js.

It uses grunt for building, testing, etc.

I'd like to know how I can specify configuration variables (i.e. authentication tokens) that can be overridden by heroku config variables.

The closest I've been able to get is a custom task that reads environment variables and writes out a json file that gets built into the site (and assigned to a global var). This works locally, but doesn't take into account heroku configs.

I even wrote a deploy script that gets heroku's configs, exports them as environment variables locally, and does the build--Which works, but the configs only get updated on app deploy. So if I do a heroku config:add CONFIG_TEST=test_value, my app doesn't see that value for CONFIG_TEST until the next time I deploy the app.

I'd like for my app to start embedding that config value in the browser JS immediately.

Any way to do this with node the way my app is set up?

Answer 1

I am not sure I understand what's wrong with simply taking config variables, at run time, from the environment. Use process.env.KEY in your code, and embed that result into whatever template you may have, and serve that as the result.

When you change Heroku config variables your process gets restarted, so it picks up the new values.

Is the problem the fact that you serve static files? If so -- can you simply change it so that you use a template engine to do some processing on them before serving?

Answer 2

OK, here's a solution for ember-app-kit using grunt-sed.

In EMBER_APP_KIT_PROJECT/tasks/options/sed.js

Add something like

module.exports = {
    version: {
        path: "./dist/",
        pattern: '{{env.API_BASE_PATH}}',
        replacement: function(){
            return process.env.API_BASE_PATH;
        },
        recursive: true
    }
};

then in your code just put

"{{env.API_BASE_PATH}}"

Now, when you run

$ grunt sed 

it will replace "{{env.API_BASE_PATH}}" with whatever's in the environment variable.