Running Rails 5 on App Engine flexible environment

It's easy to get started developing Ruby on Rails apps that run on App Engine flexible environment. Because the apps you create run on the same infrastructure that powers all of Google's products, you can be confident that they can scale to serve all of your users, whether there are a few or millions of them.

This tutorial assumes you are familiar with Rails web development. It walks you through deploying a new Rails app.

This tutorial requires Ruby 2.3.3 or newer.

Before you begin

Check off each step as you complete it.

1. check_box_outline_blank check_box Create a project in the Google Cloud Platform Console.
   If you haven't already created a project, create one now. Projects enable you to manage all Google Cloud Platform resources for your app, including deployment, access control, billing, and services.

   1. Open the GCP Console.
   2. In the drop-down menu at the top, select Create a project.
   3. Click Show advanced options. Under App Engine location, select a United States location.
   4. Give your project a name.
   5. Make a note of the project ID, which might be different from the project name. The project ID is used in commands and in configurations.
2. check_box_outline_blank check_box Enable billing for your project, and sign up for a free trial.

   If you haven't already enabled billing for your project, enable billing now, and sign up for a free trial. Enabling billing allows the app to consume billable resources such as running instances and storing data. During your free trial period, you won't be billed for any services.

3. check_box_outline_blank check_box Install the Cloud SDK.

   If you haven't already installed the Cloud SDK, install and initialize the Cloud SDK now. The Cloud SDK contains tools and libraries that enable you to create and manage resources on GCP.

Set up your local environment for Rails

Before you begin, take the following steps:

1. Install Ruby version 2.3.3 or greater.

2. Install the Rails 5 gem.

3. Install the Bundler gem.

Alternatively, you can use Cloud Shell, which comes with Ruby, Rails, and the Cloud SDK already installed.

For additional information on installing Rails and its dependencies, see the official Getting started with Rails guide.

After you complete the prerequisites, you can create and deploy a Rails app. The following sections guide you through configuring, running, and deploying an app.

Create a new app

1. Scaffold a new Rails sample app.

   rails new appengine_example
   

2. Go to the directory that contains the sample code.

   cd appengine_example
   

Run the app locally

To run the new Rails app on your local computer:

1. Install dependencies by using Bundler.

    bundle install
   

2. Start a local web server.

    bundle exec rails server
   

3. In your browser, go to http://localhost:3000/.

You see the "Yay! You’re on Rails!" message from the sample app displayed on the page.

Note: In your terminal window, press Ctrl+C to exit the web server.

Add a simple page

Now add a Welcome page to the generated Rails app.

1. To generate the scaffolding for a new page, create a new Rails controller named WelcomeController with an index action.

   bundle exec rails generate controller Welcome index
   

2. Open the file app/views/welcome/index.html.erb to see the following boilerplate HTML.

   appengine/rails-hello_world/app/views/welcome/index.html.erb

   View on GitHub

   <h1>Welcome#index</h1>
   <p>Find me in app/views/welcome/index.html.erb</p>

3. Modify the file however you like. For example, you can use the following content:

   appengine/rails-hello_world/app/views/welcome/index.html.erb

   View on GitHub

   <h1>Welcome</h1>
   <p>This is a home page for a new Rails App on Google Cloud Platform!</p>

4. Set the index controller action as the root action for Rails. Then, whenever a user visits the Rails app, they see your welcome page.

5. Open the file config/routes.rb to see the following generated content.

   appengine/rails-hello_world/config/routes.rb

   View on GitHub

   Rails.application.routes.draw do
     get 'welcome/index'
   
     # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
   end

6. To modify this file, add root 'welcome#index'.

   appengine/rails-hello_world/config/routes.rb

   View on GitHub

   Rails.application.routes.draw do
     get 'welcome/index'
   
     # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
     root 'welcome#index'
   end

7. Save the file and close it. Test the Rails app as you did before.

Deploy the app to App Engine flexible environment

App Engine flexible environment uses a file called app.yaml. to describe an app's deployment configuration. If this file isn't present, the gcloud command line tool tries to guess the deployment configuration. However, it is a good idea to provide this file because Rails requires a secret key in a production environment.

To configure the sample app for deployment to App Engine, create a new file named app.yaml at the root of your sample app directory and add the following:

appengine/rails-hello_world/app.yaml

View on GitHub

entrypoint: bundle exec rackup --port $PORT
env: flex
runtime: ruby

Configure the Rails secret key

When you deploy a Rails app in the production environment, set the environment variable SECRET_KEY_BASE to a secret key that is used to protect user session data. This environment variable is read in the config/secrets.yml file.

1. Generate a new secret key.

   bundle exec rails secret
   

2. Copy the generated secret key. You use the secret key in the next step.

3. Open the file app.yaml that you created earlier, and add an env_variables section. The env_variables sets environment variables in the production environment in App Engine flexible environment. Your app.yaml should look like the example below, with [SECRET_KEY] replaced with your copied secret key.

   appengine/rails-hello_world/app.yaml

   View on GitHub

   entrypoint: bundle exec rackup --port $PORT
   env: flex
   runtime: ruby
   
   env_variables:
     SECRET_KEY_BASE: [SECRET_KEY]

Set up an App Engine flexible environment app

If this is the first time you are deploying an app, you need to create an App Engine flexible environment app to help you select the region in which to run the Rails app. You can read more about regions and zones.

1. Create an App Engine app.

   gcloud app create
   

2. Select a region that supports App Engine flexible environment for Ruby apps.

Deploy to App Engine flexible environment

1. Before you deploy, precompile your Rails assets.

   RAILS_ENV=production bundle exec rails assets:precompile
   

2. After the assets finish compiling, deploy the sample.

   gcloud app deploy
   

Wait for the message that notifies you that the update has completed. This can take several minutes.

Access the deployed Rails app

1. To retrieve your project ID, run gcloud info.

2. In your browser, go to https://[PROJECT_ID].appspot.com.

   where:

   • [PROJECT_ID] is the project ID you retrieved in the first step.

The following content is displayed.

This time, your request is served by the Rails app running in App Engine flexible environment.

This command deploys the app as described in app.yaml and sets the newly deployed version as the default version, causing it to serve all new traffic. As the app deploys, you might see several repeated messages while the platform checks whether the app is serving. This is normal. Wait for the message that notifies you that the update of the app is complete.

If you update your app, you can deploy the updated version by entering the same command you used to deploy the app the first time. The new deployment creates a new version of your app and promotes it to the default version. The older versions of your app remain, as do their associated VM instances. Be aware that all of these app versions and VM instances are billable resources.

Read App Engine logs

Now that you have deployed your Rails app, you may want to read the logs. You can read the app logs by using the Logs Viewer located in the GCP Console, or by using gcloud app logs read. You can learn more about reading logs by using the Cloud SDK.

Clean up resources

After you've finished the Running Rails 5 in the App Engine tutorial, you can clean up the resources you created on Google Cloud Platform so you won't be billed for them in the future. The following sections describe how to delete or turn off these resources.

Delete project

The easiest way to eliminate billing is to delete the project you created for the tutorial.

To delete the project:

Caution: Deleting a project has the following effects:

• Everything in the project is deleted. If you used an existing project for this tutorial, when you delete it, you also delete any other work you've done in the project.
• Custom project IDs are lost. When you created this project, you might have created a custom project ID that you want to use in the future. To preserve the URLs that use the project ID, such as an appspot.com URL, delete selected resources inside the project instead of deleting the whole project.

If you plan to explore multiple tutorials and quickstarts, reusing projects can help you avoid exceeding project quota limits.

1. In the GCP Console, go to the Projects page.

   Go to the Projects page

2. In the project list, select the project you want to delete and click Delete.
3. In the dialog, type the project ID, and then click Shut down to delete the project.

Delete an App Engine version

To delete an app version:

1. In the GCP Console, go to the App Engine Versions page.

   Go to the Versions page

2. Click the checkbox next to the non-default app version you want to delete.
   Note: The only way you can delete the default version of your App Engine app is by deleting your project. However, you can stop the default version in the GCP Console. This action shuts down all instances associated with the version. You can restart these instances later if needed.

   In the App Engine standard environment, you can stop the default version only if your app has manual or basic scaling.

3. Click the Delete button at the top of the page to delete the app version.

What's next

• Learn how to use Cloud SQL for MySQL with Rails.

• Learn how to use Cloud SQL for PostgreSQL with Rails.

• Learn how to run the Ruby Bookshelf sample in App Engine flexible environment.

• Learn how to run the Ruby Bookshelf sample on Compute Engine.

• Learn how to run the Ruby Bookshelf sample on GKE.