Application Deployment

SSH Connection

Applications like GitHub and Heroku allow an SSH connection. To set this up, do the following:

1. Run ssh-keygen -t rsa -b 4096 -C "[email protected]" to create an RSA public and private key pair.

   • -t rsa defines the algorithm.

   • -b 4096 is the most common byte size.

   • -C "[email protected]" is the comment, which is usually your email.

2. Save the key pair to the default location: ~/.ssh. Also, set the passphrase to a default of none. This will generate an RSA public and private key pair: id_rsa and id_rsa.pub.

3. Start up a new SSH agent: eval "$(ssh-agent -s)". This will create a new agent or give you the ID of the one already running.

4. Add the private key to the SSH agent: ssh-add ~/.ssh/id_rsa.

5. In your service of choice, add the contents of the public key in the id_rsa.pub file to your account. (Just use cat to print it out.)

GitHub

The value of SSH with GitHub is that you can connect without a username and password! To test that GitHub is authenticated, run ssh -T [email protected]. You should see a success message!

Heroku

Heroku allows configuration in the command line.

1. Run heroku keys:add, and it will find id_rsa.pub automatically.

2. Then run heroku create <appName> to create new app.

3. Now Heroku needs an npm start command, which it will execute on the server. Simply add this inside scripts in package.json:

   • "start": "node path/to/app.js"

4. Heroku provides your server with its own port environment variable, so you need to add it to your app.listen function call.

const port = process.env.PORT || 3000
// NOTE: You provide a fallback value for the local dev environment

app.listen(port, ...)

Note: Make sure any URLs for other parts of your site use a relative path (e.g. /about instead of localhost:3000/about).

1. Finally, stage and commit your code and then git push heroku master. Heroku will deploy your application for you!

Avoid Global Modules

If you have a global module, this is bad for other people who want to work on your project. When they git clone your project and then npm install your dependency modules, global modules aren't included in your package.json. The solution is to add the module as a local module!

Bonus: Some of these local modules will be dev dependencies. These dependencies are separated, so the production server doesn't install unnecessary files. For example, nodemon is useful for a dev to hot reload your local website, but it's useless in a production environment. To implement a dev dependency, do the following:

• Simply flag your install as npm install --save-dev nodemon.

• Then make sure any scripts your deployment server runs don't include dev dependencies.

Note: If you want to run a command in the command line using a local module, you can use npx like npx nodemon src/app.js.