Running Rails on the Cloud Run environment

Objectives

• Create and connect a Cloud SQL database to Active Record
• Create and use Secret Manager to store and access a Rails master key securely
• Host user-uploaded media and files on Cloud Storage from Active Storage
• Use Cloud Build to automate build and database migrations
• Deploy a Rails app to Cloud Run

Costs

Before you begin

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.

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

Go to project selector

Verify that billing is enabled for your Google Cloud project .

Enable the Cloud Run, Cloud SQL, Cloud Build, Secret Manager, and Compute Engine APIs.

Enable the APIs

Install the Google Cloud CLI.

If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity .

To initialize the gcloud CLI, run the following command:

gcloud  
init

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

Go to project selector

Verify that billing is enabled for your Google Cloud project .

Enable the Cloud Run, Cloud SQL, Cloud Build, Secret Manager, and Compute Engine APIs.

Enable the APIs

Install the Google Cloud CLI.

If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity .

To initialize the gcloud CLI, run the following command:

gcloud  
init

1. Ensure sufficient permissions are available to the account used for this tutorial.

Prepare your environment

This tutorial uses several Google Cloud services to provide the database, media storage, and secret storage that support the deployed Rails application. Prepare your environment by configuring a region to deploy the services in and by cloning the Rails app.

Set the default project and region

1. Set the default project configuration for the gcloud CLI by running the following command:

    gcloud  
   config  
    set 
     
   project  
    PROJECT_ID 
    
   

   Replace PROJECT_ID with your Google Cloud project ID

2. Configure your region:

     export 
     
    REGION 
    = 
    REGION 
    
   

   Replace REGION with an appropriate location. For efficiency between services, all services should be deployed in the same region. For more information about the closest region to you, see Products available by location .

Clone the Rails app

The code for the Rails sample app is in the GoogleCloudPlatform/ruby-docs-samples repository on GitHub.

1. Clone the repository:

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

2. Go to the directory that contains the sample code and run the following commands to make sure that the application is properly set up with the required gems and dependencies:

   Linux/macOS

     cd 
     
    ruby 
    - 
    docs 
    - 
    samples 
    / 
    run 
    / 
    rails 
    bundle 
     
    install 
    
   

   Windows

     cd 
     
    ruby 
    - 
    docs 
    - 
    samples 
    \ 
    run 
    \ 
    rails 
    bundle 
     
    install 
    
   

Prepare the backing services

This tutorial uses a number of Google Cloud services to provide the database, media storage, and secret storage that support the deployed Rails project. These services are deployed in a specific region. For efficiency between services, it is best that all services are deployed in the same region. For more information about the closest region to you, see Products available by location .

Set up a Cloud SQL for PostgreSQL instance

Rails supports multiple relational databases, including several offered by Cloud SQL. This tutorial uses PostgreSQL, an open source database commonly used by Rails apps.

The following sections describe the creation of a PostgreSQL instance, database, and database user for your Rails app.

Create a PostgreSQL instance

Create a database

Create a user

Generate a random password for the database user, and write it to a file called dbpassword :

  cat 
  
 /dev/u 
 random 
  
 | 
  
 LC_ALL 
 = 
 C 
  
 tr 
  
 - 
 dc 
  
 '[:alpha:]' 
 | 
  
 fold 
  
 - 
 w 
  
 50 
  
 | 
  
 head 
  
 - 
 n1 
 > 
 dbpassword 
 

Set up an Artifact Registry repository

Use Artifact Registry to create a repository to store your container image.

Set up a Cloud Storage bucket

You can host Rails static assets and user-uploaded media in highly available object storage using Cloud Storage.

After creating a bucket, to make the uploaded images public, change the permissions of image objects to be readable by everyone.

Store secret values in Secret Manager

Now that the backing services are configured, Rails needs secure information, such as passwords, to access these services. Instead of putting these values directly into the Rails source code, this tutorial uses Rails Credentials and Secret Manager to store this information securely.

Create encrypted credentials file and store key as Secret Manager secret

Rails stores secrets in an encrypted file called 'config/credentials.yml.enc'. The file can be decrypted with the local config/master.key or the environment variable ENV["RAILS_MASTER_KEY"] . In the credentials file, you can store the Cloud SQL instance database password and other access keys for external APIs.

You can store this key securely in Secret Manager. Then, you can grant Cloud Run and Cloud Build access to the key by granting access to their respective service accounts . Service accounts are identified by an email address that contains the project number .

1. Generate the config/credentials.yml.enc file with the following command:

    bin/rails  
   credentials:edit 
   

   The command will create a config/master.key if no master key is defined, and create a config/credentials.yml.enc file if the file does not exist. This will open a temporary file in your default $EDITOR with the decrypted contents for the secrets to be added.

2. Copy and paste the newly created PostgreSQL instance database password from the dbpassword file into the credentials file:

    secret_key_base:  
   GENERATED_VALUE
   gcp:  
   db_password:  
    PASSWORD 
    
   

   Secrets can be accessed with Rails.application.credentials . For example, Rails.application.credentials.secret_key_base should return the application's secret key base and Rails.application.credentials.gcp[:db_password] should return your database password.

3. The config/credentials/yml.enc is stored encrypted, but config/master.key can be stored in Secret Manager.

   Console

   1. In the Google Cloud console, go to the Secret Manager page.

      Go to the Secret Manager page

   2. Click Create secret

   3. In the Namefield, enter a name for the secret RAILS_SECRET_NAME .

   4. In the Secret valuedialog, paste the mater.key value into the box.

   5. Click Create secret.

   6. On the Secret details page of your secret, note the project number:

      projects/ PROJECTNUM /secrets/ RAILS_SECRET_NAME

   7. In the Permissionstab, click Add Member

   8. In the New Membersfield, enter PROJECTNUM -compute@developer.gserviceaccount.com , and then press Enter .

   9. In the New Membersfield, enter PROJECTNUM @cloudbuild.gserviceaccount.com , and then press Enter .

   10. In the Roledrop-down menu, select Secret Manager Secret Accessor.

   11. Click Save.

   gcloud

   1. Create a new secret with the value of the config/master.key:

       gcloud  
      secrets  
      create  
       RAILS_SECRET_NAME 
        
      --data-file  
      config/master.key 
      

      Replace RAILS_SECRET_NAME with a name for the new secret.

   2. To confirm the creation of the secret, check it:

       gcloud  
      secrets  
      describe  
       RAILS_SECRET_NAME 
      gcloud  
      secrets  
      versions  
      access  
      latest  
      --secret  
       RAILS_SECRET_NAME 
       
      

   3. Get the value of the project number:

       gcloud  
      projects  
      describe  
       PROJECT_ID 
        
      --format = 
       'value(projectNumber)' 
       
      

   4. Grant access to the secret to the Cloud Run service account:

       gcloud  
      secrets  
      add-iam-policy-binding  
       RAILS_SECRET_NAME 
        
       \ 
        
      --member  
      serviceAccount: PROJECTNUM 
      -compute@developer.gserviceaccount.com  
       \ 
        
      --role  
      roles/secretmanager.secretAccessor 
      

      Replace PROJECTNUM with the project number value.

   5. Grant access to the secret to the Cloud Build service account:

       gcloud  
      secrets  
      add-iam-policy-binding  
       RAILS_SECRET_NAME 
        
       \ 
        
      --member  
      serviceAccount: PROJECTNUM 
      @cloudbuild.gserviceaccount.com  
       \ 
        
      --role  
      roles/secretmanager.secretAccessor 
      

      In the output, confirm that bindings lists the two service accounts as members.

Connect Rails app to production database and storage

This tutorial uses a PostgreSQL instance as the production database and Cloud Storage as the storage backend. For Rails to connect to the newly created database and storage bucket, you need to specify all the information needed to access them in the .env file. The .env file contains the configuration for the application environment variables. The application will read this file using the dotenv gem. Since the secrets are stored in credentials.yml.enc and Secret Manager, the .env doesn't have to be encrypted because it doesn't hold any sensitive credentials.

1. To configure the Rails app to connect with the database and storage bucket, open the .env file.

2. Modify the .env file configuration to the following. Use the value of MEDIA_BUCKET_SUFFIX that you used when you created the bucket.

     PRODUCTION_DB_NAME 
    : 
     
     DATABASE_NAME 
    
    PRODUCTION_DB_USERNAME 
    : 
     
     DATABASE_USERNAME 
    
    CLOUD_SQL_CONNECTION_NAME 
    : 
     
     PROJECT_ID 
    
    : 
     REGION 
    
    : 
     INSTANCE_NAME 
    
    GOOGLE_PROJECT_ID 
    : 
     
     PROJECT_ID 
    
    STORAGE_BUCKET_NAME 
    : 
     
     PROJECT_ID 
    
    - 
     MEDIA_BUCKET_SUFFIX 
    
    
   

   The Rails app is now set up to use Cloud SQL and Cloud Storage when deploying to Cloud Run.

Deploy the app to Cloud Run

With the backing services set up, you can now deploy the app as a Cloud Run service.

1. Using the supplied cloudbuild.yaml , use Cloud Build to build the image, run the database migrations, and populate the static assets:

    gcloud  
   builds  
   submit  
   --config  
   cloudbuild.yaml  
    \ 
     
   --substitutions  
    _SERVICE_NAME 
    = 
    SERVICE_NAME 
   ,_INSTANCE_NAME = 
    INSTANCE_NAME 
   ,_REGION = 
    REGION 
   ,_SECRET_NAME = 
    RAILS_SECRET_NAME 
    
   

   Replace SERVICE_NAME with the name for your service. This first build takes a few minutes to complete. If the build timed out, increase the timeout duration by inserting --timeout=2000s into the build command.

2. When the build is successful, deploy the Cloud Run service for the first time, setting the service region, base image, and connected Cloud SQL instance:

    gcloud  
   run  
   deploy  
    SERVICE_NAME 
     
    \ 
     
   --region  
    REGION 
     
    \ 
     
   --image  
    REGION 
   -docker.pkg.dev/ PROJECT_ID 
   /cloud-run-source-deploy/ SERVICE_NAME 
     
    \ 
     
   --add-cloudsql-instances  
    PROJECT_ID 
   : REGION 
   : INSTANCE_NAME 
     
    \ 
     
   --allow-unauthenticated 
   

   You should see output that shows the deployment succeeded, with a service URL.

3. To see the deployed service, go to the service URL.

   

4. Try to upload a new photo. If the photo successfully uploads, the Rails application has been successfully deployed.

   

Update the application

While the initial provisioning and deployment steps were complex, making updates is a simpler process:

1. Run the Cloud Build build and migration script:

    gcloud  
   builds  
   submit  
   --config  
   cloudbuild.yaml  
    \ 
     
   --substitutions  
    _SERVICE_NAME 
    = 
    SERVICE_NAME 
   ,_INSTANCE_NAME = 
    INSTANCE_NAME 
   ,_REGION = 
    REGION 
   ,_SECRET_NAME = 
    RAILS_SECRET_NAME 
    
   

2. Deploy the service, specifying only the region and image:

    gcloud  
   run  
   deploy  
    SERVICE_NAME 
     
    \ 
     
   --region  
    REGION 
     
    \ 
     
   --image  
    REGION 
   -docker.pkg.dev/ PROJECT_ID 
   /cloud-run-source-deploy/ SERVICE_NAME 
    
   

Understand the code

The Rails sample app was created using standard Rails commands. The following commands create the cat_album app and use the scaffold command to generate a model, controller, and views for the Photo resource:

 rails  
new  
cat_album
rails  
generate  
scaffold  
Photo  
caption:text 

Database connection

The config/database.yml file contains the configuration needed to access your databases in different environments (development, test, production). For example, the production database is configured to run in Cloud SQL for PostgreSQL. The database name and username are set through environment variables in the .env file, while the database password is stored inside the config/credentials.yml.enc file, which requires the RAILS_MASTER_KEY to decrypt.

When the app runs on Cloud Run (fully managed), it connects to the PostgreSQL instance using a socket provided by the Cloud Run environment. When the app runs on your local machine, it connects to the PostgreSQL instance using the Cloud SQL Auth proxy.

  production 
 : 
  
<< : 
  
 *default 
  
 database 
 : 
  
< % 
 = ENV["PRODUCTION_DB_NAME"] % 
>  
 username 
 : 
  
< % 
 = ENV["PRODUCTION_DB_USERNAME"] % 
>  
 password 
 : 
  
< % 
 = Rails.application.credentials.gcp[:db_password] % 
>  
 host 
 : 
  
 "<%= 
  
 ENV.fetch(" 
 DB_SOCKET_DIR") { '/cloudsql' } %>/<%= ENV["CLOUD_SQL_CONNECTION_NAME"] %>" 
 

Cloud-stored user uploaded media

Rails uses Active Storage to upload files to storage providers. The config/storage.yml and config/environments/production.rb files specify Cloud Storage as the service provider in the production environment.

  google 
 : 
  
 service 
 : 
  
 GCS 
  
 project 
 : 
  
< % 
 = ENV["GOOGLE_PROJECT_ID"] % 
>  
 bucket 
 : 
  
< % 
 = ENV["STORAGE_BUCKET_NAME"] % 
> 

  # Store uploaded files on the local file system (see config/storage.yml for options). 
 config 
 . 
 active_storage 
 . 
 service 
  
 = 
  
 :google 
 

Automation with Cloud Build

The cloudbuild.yaml file performs not only the typical image build steps (creating the container image and pushing that to Artifact Registry), but also the Rails database migrations. This migration is performed by using Cloud Run jobs, where a custom command is used so that the container performs the migration, rather than the default web server.

  steps 
 : 
  
 - 
  
 id 
 : 
  
 "build 
  
 image" 
  
 name 
 : 
  
 "gcr.io/cloud-builders/docker" 
  
 entrypoint 
 : 
  
 'bash' 
  
 args 
 : 
  
 [ 
 "-c" 
 , 
  
 "docker 
  
 build 
  
 --build-arg 
  
 MASTER_KEY=$$RAILS_KEY 
  
 -t 
  
 ${_IMAGE_NAME} 
  
 . 
  
 " 
 ] 
  
 secretEnv 
 : 
  
 [ 
 "RAILS_KEY" 
 ] 
  
 - 
  
 id 
 : 
  
 "push 
  
 image" 
  
 name 
 : 
  
 "gcr.io/cloud-builders/docker" 
  
 args 
 : 
  
 [ 
 "push" 
 , 
  
 "${_IMAGE_NAME}" 
 ] 
  
 - 
  
 id 
 : 
  
 "apply 
  
 migrations" 
  
 name 
 : 
  
 "gcr.io/google.com/cloudsdktool/cloud-sdk" 
  
 entrypoint 
 : 
  
 /bin/bash 
  
 secretEnv 
 : 
  
 [ 
 "RAILS_KEY" 
 ] 
  
 args 
 : 
  
 - 
  
 "-c" 
  
 - 
  
 | 
  
 gcloud run jobs create migrate-job \ 
  
 --region ${_REGION} \ 
  
 --image ${_IMAGE_NAME} \ 
  
 --set-cloudsql-instances ${_CLOUD_SQL_CONNECTION_NAME} \ 
  
 --set-env-vars RAILS_MASTER_KEY=$$RAILS_KEY \ 
  
 --command bundle \ 
  
 --args exec,rails,db:migrate \ 
  
 --execute-now --wait && \ 
  
 gcloud run jobs delete  migrate-job --region ${_REGION} -q 
 options 
 : 
  
 dynamicSubstitutions 
 : 
  
 true 
 substitutions 
 : 
  
 _REGION 
 : 
  
 us-central1 
  
 _SERVICE_NAME 
 : 
  
 rails-cat-album 
  
 _INSTANCE_NAME 
 : 
  
 cat-album 
  
 _SECRET_NAME 
 : 
  
 rails-master-key 
  
 _AR_REPO_NAME 
 : 
  
 cloud-run-source-deploy 
  
 _IMAGE_NAME 
 : 
  
 ${_REGION}-docker.pkg.dev/${PROJECT_ID}/${_AR_REPO_NAME}/${_SERVICE_NAME} 
  
 _CLOUD_SQL_CONNECTION_NAME 
 : 
  
 ${PROJECT_ID}:${_REGION}:${_INSTANCE_NAME} 
 availableSecrets 
 : 
  
 secretManager 
 : 
  
 - 
  
 versionName 
 : 
  
 projects/${PROJECT_ID}/secrets/${_SECRET_NAME}/versions/latest 
  
 env 
 : 
  
 RAILS_KEY 
 images 
 : 
  
 - 
  
 "${_IMAGE_NAME}" 
 

Substitution variables are used in this configuration. Changing the values in the file directly means the --substitutions flag can be dropped at migration time.

In this configuration, only existing migrations in the db/migrate directory are applied. To create migration files, see Active Record Migrations .

To build the image and apply migrations, the Cloud Build configuration needs access to the RAILS_MASTER_KEY secret from Secret Manager. The availableSecrets field sets the secret version and environment variables to use for the secret. The master key secret is passed in as an argument in the build image step and then gets set to be the RAILS_MASTER_KEY in the Dockerfile when building the image.

  ARG 
  
MASTER_KEY ENV 
  
 RAILS_MASTER_KEY 
 = 
 ${ 
 MASTER_KEY 
 } 
 

To extend the Cloud Build configuration to include the deployment in the one configuration without having to run two commands, see Continuous deployment from git using Cloud Build . This requires IAM changes, as described.

Cleanup

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.