Create a Ruby app in the App Engine flexible environment

Region ID

The REGION_ID is an abbreviated code that Google assigns based on the region you select when you create your app. The code does not correspond to a country or province, even though some region IDs may appear similar to commonly used country and province codes. For apps created after February 2020, REGION_ID.r is included in App Engine URLs. For existing apps created before this date, the region ID is optional in the URL.

Learn more about region IDs.

This quickstart demonstrates how to create and deploy an app that displays a short message. You can use the sample application in this quickstart for any supported version of Ruby, by specifying the runtime version and operating system in your app.yaml file.

Before you begin

  1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

  2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Go to project selector

  3. Make sure that billing is enabled for your Google Cloud project.

  4. Enable the Cloud Build API.

    Enable the API

  5. Install the Google Cloud CLI.

  6. To initialize the gcloud CLI, run the following command: 

    gcloud init

  7. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Go to project selector

  8. Make sure that billing is enabled for your Google Cloud project.

  9. Enable the Cloud Build API.

    Enable the API

  10. Install the Google Cloud CLI.

  11. To initialize the gcloud CLI, run the following command: 

    gcloud init

Additional prerequisites

  1. Initialize your App Engine app with your project and choose its region:

    gcloud app create --project=[YOUR_PROJECT_ID]

    When prompted, select the region where you want to locate your App Engine application.

  2. Install the following on your local machine:

App Engine locations

App Engine is regional, which means the infrastructure that runs your apps is located in a specific region, and Google manages it so that it is available redundantly across all of the zones within that region.

Meeting your latency, availability, or durability requirements are primary factors for selecting the region where your apps are run. You can generally select the region nearest to your app's users, but you should consider the locations where App Engine is available as well as the locations of the other Google Cloud products and services that your app uses. Using services across multiple locations can affect your app's latency as well as its pricing.

You cannot change an app's region after you set it.

If you already created an App Engine application, you can view its region by doing one of the following:

This quickstart demonstrates a simple Ruby app written with the Sinatra web framework that you can deploy to App Engine. Although this sample uses Sinatra, you can use other frameworks such as Ruby on Rails.

Download the Hello World app

We've created a Hello World app for App Engine so you can quickly get a feel for deploying an app to the Google Cloud.

  1. Clone the Hello World sample app repository to your local machine.

    git clone https://github.com/GoogleCloudPlatform/ruby-docs-samples

    Alternatively, you can download the sample as a zip file and extract it.

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

       cd ruby-docs-samples/appengine/flexible/hello_world

Run Hello World on your local machine

This example uses Bundler to run the Hello World app on your local computer:

  1. If you don't already have the programming language installed for your runtime, download and install Ruby.

    Download and install Ruby

  2. Install Bundler:

    gem install bundler

  3. Install dependencies for this project:

    bundle install

  4. Start a local web server.

    bundle exec ruby app.rb -p 8080

  5. In your web browser, enter:

    http://localhost:8080

The Hello World message from the sample app displays on the page. In your terminal window, press Ctrl+C to exit the web server.

Deploy and run Hello World on App Engine

To deploy your app to the App Engine flexible environment:

  1. Deploy the Hello World app by running the following command from the flexible/hello_world directory: 

    gcloud app deploy

    Learn about the optional flags.

    Common gcloud command flags

    • Include the --version flag to specify an ID that uniquely identifies that version of your app, otherwise one is generated for you. Example: --version [YOUR_VERSION_ID]
    • Include the --project flag to specify an alternate Google Cloud project ID to what you initialized as the default in the gcloud tool. Example: --project [YOUR_PROJECT_ID]

    Example:

    gcloud app deploy --version pre-prod-5 --project my-sample-app

    To learn more about deploying your app from the command line, see Testing and Deploying Your App . For a list of all the command flags, see the gcloud app deploy reference.

  2. Launch your browser to view the app at https://PROJECT_ID.REGION_ID.r.appspot.com 

    gcloud app browse
     where PROJECT_ID represents your Google Cloud project ID.

This time, the page that displays the Hello World message is delivered by a web server running on an App Engine instance.

Congratulations! You've deployed your first App Engine app to the App Engine flexible environment!

If you encountered any errors deploying your application, check the troubleshooting tips.

See the following sections for information about cleaning up as well as links to possible next steps that you can take.

Clean up

To avoid incurring charges, you can delete your Google Cloud project to stop billing for all the resources used within that project.

  1. In the Google Cloud console, go to the Manage resources page.

    Go to Manage resources

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

What's next

Learn the whole platform

Now that you know what it's like to develop and deploy App Engine apps, you can explore the rest of Google Cloud. You already have the Google Cloud CLI installed which gives you the tools to interact with products like Cloud SQL, Cloud Storage, Firestore, and more.

Learn about the App Engine flexible environment

Here are some topics to help continue your learning about App Engine:

Hello World code review

Hello World is the simplest possible App Engine app, as it contains only one service, has only one version, and all of the code is located within the app's root directory. This section describes each of the app files in detail.

app.rb

The Hello World app is a basic one-file Sinatra app:

require "sinatra"

get "/" do
  "Hello world!"
end

app.yaml

The app.yaml file describes the following configuration for your app:

  • Sets env: flex, indicating your app uses the App Engine flexible environment.

  • Specifies the runtime used by the app. 

    runtime: ruby
env: flex
entrypoint: bundle exec ruby app.rb

runtime_config:
  operating_system: ubuntu22

# This sample incurs costs to run on the App Engine flexible environment.
# The settings below are to reduce costs during testing and are not appropriate
# for production use. For more information, see:
# https://cloud.google.com/appengine/docs/flexible/ruby/configuring-your-app-with-app-yaml
manual_scaling:
  instances: 1
resources:
  cpu: 1
  memory_gb: 0.5
  disk_size_gb: 10

Gemfile

Gemfile is used to specify the app's RubyGem dependencies, and Bundler is used to declare and install dependencies. The Hello World app requires one Ruby gem: the Sinatra web framework:

source "https://rubygems.org"

gem "sinatra"
gem "webrick", "~> 1.8"