Google Cloud build fails due to rails db:migrate - ruby-on-rails

Question

I'm following the 'Running Rails on the Cloud Run environment' instructions and have hit a snag. I used their provided github repo and the google cloud shell and I had success in launching the working application.
Now, I am trying to integrate Cloud Run into my rails template. While 'Deploying the app to Cloud Run' using the cloudbuild.yaml file provided, the build crashes during database migration. I am using postgreSQL. Here are the error details:
The error
"bundle exec rails db:migrate" ->
"ActiveRecord::ConnectionNotEstablished: could not connect to server: No such file or directory"
I think I've traced it to database.yml file where Google recommends this host:
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"] %>"
It is unclear where this ENV.fetch("DB_SOCKET_DIR") comes from [at least to me, I'm new]. Their git repo holds a folder where I found templates for another build that included an app.standard.yaml and a config/database_unix.yml that I've tried integrating.
app.standard.yaml:
entrypoint: bundle exec rackup --port $PORT
runtime: ruby27
env_variables:
SECRET_KEY_BASE: <SECRET_KEY>
RAILS_ENV: production
INSTANCE_UNIX_SOCKET: /cloudsql/<PROJECT-ID>:<INSTANCE-REGION>:<INSTANCE-NAME>
DB_USER: <YOUR_DB_USER_NAME>
DB_PASS: <YOUR_DB_PASSWORD>
DB_NAME: <YOUR_DB_NAME>
beta_settings:
cloud_sql_instances: <PROJECT-ID>:<INSTANCE-REGION>:<INSTANCE-NAME>
database_unix.yml:
# [START cloud_sql_postgres_activerecord_connect_unix]
unix: &unix
adapter: postgresql
# Configure additional properties here.
# [END cloud_sql_postgres_activerecord_connect_unix]
pool: 5
timeout: 5000
# [START cloud_sql_postgres_activerecord_connect_unix]
# Note: Saving credentials in environment variables is convenient, but not
# secure - consider a more secure solution such as
# Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
# keep secrets safe.
username: <%= ENV["DB_USER"] %> # e.g. "my-database-user"
password: <%= ENV["DB_PASS"] %> # e.g. "my-database-password"
database: <%= ENV.fetch("DB_NAME") { "vote_development" } %>
# Specify the Unix socket path as host
host: "<%= ENV["INSTANCE_UNIX_SOCKET"] %>"
# [END cloud_sql_postgres_activerecord_connect_unix]
development:
<<: *unix
# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
<<: *unix
pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 1 } %>
database: <%= ENV.fetch("DB_NAME") { "vote_test" } %>
production:
<<: *unix
database: <%= ENV.fetch("DB_NAME") { "vote_production" } %>
Some other solutions I've seen mention this instead of host:
socket: “/cloudsql/project_id:us-central1:photo-album-production”
I tried this with no luck. I cloned the repo to my machine and re-tried the Cloud Run instructions. No success this time as it's getting the same migration error. Am I thinking about this wrong?

Answer 1

Check this out: https://cloud.google.com/sql/docs/postgres/connect-build.
In short, you'll need to run the Cloud SQL Auth Proxy to create a Unix socket in Cloud Build so your app can connect.
If you're using a private IP instance, you'll need to make sure you're using private pools.