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Preparing Your Application for Deployment
9:47Now you know what Heroku is, let's get our application ready and deploy it!
Now you have
the Heroku Toolbelt installed,
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it's now time to deploy our application.
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Let me show you what the application is.
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It's a simple HTTP server, but
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just says Hello World no
matter where you navigate to.
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Heroku users get to deploy applications.
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So if you haven't got your
application checked since the git,
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which you should have by now,
you need to do that.
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My application is already committed.
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Just committing your application to
git is not enough to deploy to Heroku.
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There's a couple of things you need to
do to prepare your app for deployment.
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Make sure you have a package.json file.
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Because Heroku doesn't know which version
of Node you've been developing for,
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you need to specify what version of
Node.js that Heroku will install and
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use for your application.
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You need to have a special file
at the root of your application
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that will let Heroku know
how to run your application.
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I'll go into more detail
about this file shortly.
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Then create the application on
Heroku using the Heroku Toolbelt.
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This will link your Heroku application
as a remote git repository too.
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Each Heroku application is stored in
virtual machine containers called dinos.
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Each dino has its own
configuration settings, for
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example, the port number that
it routes web traffic to.
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There's a way you can
programmatically access this, and
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I'll show you that in a minute.
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Let's first create a package.json file.
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We do this by using npm init.
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A package.json file helps manage
dependencies for your project,
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whether if it's an application or
an npm package.
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Now there's no dependencies for
this application.
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But there is one dependency that you don't
normally see in a package.json file,
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unless you're deploying it to Heroku,
and that's engines.
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The engines key is to tell Heroku
which version of node.js to use when
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running our application.
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As of this recording,
the latest long term support version of
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node.js is 4.2.4, so let's use that.
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Next we need to tell Heroku how
we need to run our application.
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We run our application with node app.js.
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Heroku uses a special file called
a procfile or a process file.
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A process is a running application.
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You can tell Heroku any
number of processes.
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In this case, you'll need at least one for
the web server.
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You first start with the name of
your process followed by a colon,
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then the command you
want the process to run.
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Let's commit our changes.
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Next, let's create
the application on Heroku.
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You'll need to log into Heroku if you
haven't already with Heroku log in.
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If you haven't used it before,
you may see a screen like this.
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Don't worry.
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Fill in your credentials,
and you should be logged in.
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Heroku Toolbelt is a command line
utility to help you manage your
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applications using commands.
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Type heroku help to see
a list of command topics.
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See, there's an apps topic,
used to manage applications, create and
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destroy them, for example.
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To see a list of commands in that
topic area, type heroku help apps.
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The first command is Heroku apps:create,
with an optional application name.
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If you don't include a name,
they'll generate one for you.
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The application name translates to a
subdomain to access your replication app.
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If you don't want something random,
choose something yourself.
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I choose helloworld-treehouse.
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Since I picked this name, no one else can.
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During the application creation process,
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Heroku adds a new remote repository to
your git repository on your local machine.
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An example of another remote
repository is a GitHub repository.
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This is typically called origin.
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When you do git push origin master,
it pushes everything from
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your master branch on your local machine
to the master branch on GitHub the origin.
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With Heroku,
it creates a remote called heroku.
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So to deploy to Heroku,
you can simply do git push, heroku master.
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But what you want to do before deploying
to Heroku is test that it runs locally.
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To do this,
you use the heroku local command.
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If you notice,
it says it's running on port 5000.
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However, our application
runs on port 1337.
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There is a disconnect.
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If you try and visit 5000,
it's not there, but 1337 is.
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Heroku expects that your application
coding will handle an environmental
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variable called port.
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An environment variable is a variable that
can be accessed by the process and used.
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Heroku local sets up the port
environment variable
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just like it does in the Heroku
live hosted environment.
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Just simply put process.env.port
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followed by the or operator and
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then the default port of your choosing.
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What this code does is it sets the port
to whatever the environment variable is.
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If there isn't one,
it will set it to 1337.
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If we terminate the process with Ctrl+C,
when we do heroku
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local now, it correctly runs at port 5000.
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If we kill this process
again with Ctrl+C and
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directly run the app with node app.js,
it will run
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on port 1337, since we're not running it
in an environment where the port is set.
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Finally, we can commit our changes.
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We can push them using
git push heroku master.
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It's now deployed on Heroku.
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If your code is on GitHub,
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you probably want to deal with
git push origin master right now.
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We can now visit our
applicationname.herokuapp.com or
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type heroku open to open
it up in a web browser.
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No!
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There is an error with our application,
and this is a common gotcha.
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It may work on your local environment,
but it may not work on Heroku.
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And the reason is this.
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Now, the reason it doesn't work on Heroku,
but
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it does on our local machine is
because we're using a hostname here.
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So let's just remove these because
hostname is actually optional, so
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it will still work on our local machine,
and in theory, it should work on Heroku.
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So let's save our file.
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And do git status, and
we've only modified our app so
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let's do git add, git commit -m "Removed
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hostname", git push heroku master.
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When we do heroku open now, it works.
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Cool.
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And that's it.
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For further reading,
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check out Getting Started with
Node.js on Heroku's Dev Center.
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