byau/rails-deployment-heroku

Step through the process of deploying a Rails app to Heroku.

Rails Deployment with Heroku

You've learned a lot about how to build a Rails application over the last few weeks. Now let's 'go public' and share our apps with the world!

Prerequisites

• ga-wdi-boston/rails-api
• ga-wdi-boston/rails-activerecord-crud

Objectives

By the end of this, developers should be able to:

• Create a heroku app from the command line
• Push the latest code to heroku
• Migrate the production database

Preparation

1. No forking is necessary for this talk.

Set Up A Heroku Account

The first step is creating an account on Heroku, which you can do at https://www.heroku.com. You will be sent an activation email, so be sure to activate your account.

Install Heroku Toolbelt

The Heroku Toolbelt can be found here. Download and install it.

Login To Heroku

Run heroku login; you should be prompted for the credentials for your Heroku account. Once you log in, if you're prompted to add the credentials to your keychain, say yes.

Deploying to Heroku

Now you're setup to use heroku. Every time you want to deploy a new application, follow these steps:

• Create a heroku app from the command line (heroku create)
• Add the rails_12factor gem to the production group in your Gemfile, if it doesn't already exist.
• Make sure you have specified a ruby version in your Gemfile. It should match the version referenced in .ruby-version, if that file exists.
• bundle install to make sure Gemfile.lock is up-to-date.
• Push the latest code to heroku (git push heroku master)
• Migrate the production database (herok run rake db:migrate)
• If you have seeds or examples, you may wish to run those with heroku run as well.

Let's look at each of these steps in detail.

Create a New Heroku App

Go to the root of your repo and run heroku create. This will create a strangely named app, and add a new remote repository to your repo called heroku. You can look more closely at it by typing git remote -v. You should see something like this:

    heroku  git@heroku.com:agile-badlands-7658.git (fetch)
    heroku  git@heroku.com:agile-badlands-7658.git (push)
    origin  git@github.com:tdyer/wdi_4_rails_hw_tdd_hacker_news.git (fetch)
    origin  git@github.com:tdyer/wdi_4_rails_hw_tdd_hacker_news.git (push)

Add rails_12factor

Add the following to your Gemfile, and run bundle install.

group :production do
     gem 'rails_12factor'
end

Specify a Ruby Version

Next, you should specify the particular version of Ruby that your app is using, since it may sometimes cause issues (and in any case, Heroku will complain if you don't).

# Gemfile
source 'https://rubygems.org'
+ ruby '2.2.4'

Every time you edit your Gemfile, you must run bundle install afterward. Always commit Gemfile and Gemfile.lock together, and always commit them immediately after adding a new gem.

Push master to Heroku

Only keep clean, working code on master. After you work on a feature and complete it, merge it into master. Push your updated master to GitHub, then deploy to Heroku.

git checkout master
git merge my-feature # merge your working code
git push # update GitHub
git push heroku master # udpate heroku

Update Heroku's Database

Once you've deployed your code, you can safely run new migrations. You'll need to do this step every time you have new migrations.

heroku run rake db:migrate

If you have seeds or examples, or if you've updated seeds or examples, you should also run them on heroku.

heroku run rake db:seed
heroku run rake db:examples

Check Your Work

Restart your application and check it out in the browser.

heroku restart
heroku open

You'll probably see something like this:

That's normal, unless you have defined a root route.

Changing Your App Name

At any point, you can pick a new name for your app. It must be unique across all apps deployed to heroku.

heroku apps:rename newname

Your app will become immediately available at it's new subdomain, newname.herokuapp.com.

Heroku Command Reference

A full list of Heroku commands can be access by running heroku --help; below are some of the more common ones.

Behavior	Commands
heroku apps:info	Get info about ALL of our Heroku apps.
heroku apps:info --app {name_of_app}	Get info about a specific Heroku app.
heroku apps:open --app {name_of_app}	Open any given Heroku app (other than the one we're currently working with.)
heroku config	Environmental variables in your current Heroku app.
heroku logs	Logs from the currently running app.
heroku ps	Processes running in your heroku application.
heroku releases	Each time you deploy to heroku you are creating a "release". This command shows all releases.
heroku pg:info	Access Postgres from within Heroku and show the heroku plan, connections, pg version, data size, tables.
heroku pg:psql	... and open a psql console.
heroku run ...	Run a program from within Heroku.

WARNING: Ephemeral Filesystem

One serious limitation of Heroku is that it provides an 'ephemeral filesystem'; if you save something, like an uploaded image file, it will disappear when your app is restarted or redeployed.

As an example, try running the following commands:

heroku run bash
touch happy.txt; echo 'is happy' > happy.txt
cat happy.txt

Then, hit Ctrl-D to get out of heroku bash shell. If you re-open the shell and run ls -l, happy.txt will be missing!

The typical workaround is to save files in cloud storage such as Amazon S3; more on this in the near future.

Additional Resources

• Heroku Command Line

License

Source code distributed under the MIT license. Text and other assets copyright General Assembly, Inc., all rights reserved.