Add PostgreSQL ActiveRecord Sample (GoogleCloudPlatform#559)

* copy mysql sample app as template

* updated database.yml and app.yaml

* update readme

* updated region tag

* Update cloud-sql/postgres/activerecord/README.md

Co-Authored-By: Kurtis Van Gent <31518063+kurtisvg@users.noreply.github.com>

* addressed PR feedback and added GAE standard deployment instructions

* update license headers

Co-authored-by: Kurtis Van Gent <31518063+kurtisvg@users.noreply.github.com>

Author: shubha-rajan

cloud-sql/postgres/activerecord/.gitignore

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+# See https://help.github.com/articles/ignoring-files for more about ignoring files.
+#
+# If you find yourself ignoring temporary files generated by your text editor
+# or operating system, you probably want to add a global ignore instead:
+#   git config --global core.excludesfile '~/.gitignore_global'
+
+# Ignore bundler config.
+/.bundle
+
+# Ignore all logfiles and tempfiles.
+/log/*
+/tmp/*
+!/log/.keep
+!/tmp/.keep
+
+# Ignore uploaded files in development
+/storage/*
+!/storage/.keep
+
+/node_modules
+/yarn-error.log
+
+/public/assets
+.byebug_history
+
+**/*.sqlite3
+
+# Ignore master key for decrypting credentials and more.
+/config/master.key

cloud-sql/postgres/activerecord/Gemfile

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+source "https://rubygems.org"
+git_source(:github) { |repo| "https://github.com/#{repo}.git" }
+
+# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
+gem "rails", "~> 5.2.3"
+# Use mysql as the database for Active Record
+gem "pg", "~> 0.21.0"
+# Use Puma as the app server
+gem "puma", "~> 3.11"
+# Use SCSS for stylesheets
+gem "sass-rails", "~> 5.0"
+# Use Uglifier as compressor for JavaScript assets
+gem "uglifier", ">= 1.3.0"
+# See https://github.com/rails/execjs#readme for more supported runtimes
+# gem 'mini_racer', platforms: :ruby
+
+# Use CoffeeScript for .coffee assets and views
+gem "coffee-rails", "~> 4.2"
+# Turbolinks makes navigating your web application faster. Read more: https://github.com/turbolinks/turbolinks
+gem "turbolinks", "~> 5"
+# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
+gem "jbuilder", "~> 2.5"
+# Use Redis adapter to run Action Cable in production
+# gem 'redis', '~> 4.0'
+# Use ActiveModel has_secure_password
+# gem 'bcrypt', '~> 3.1.7'
+
+# Use ActiveStorage variant
+# gem 'mini_magick', '~> 4.8'
+
+# Use Capistrano for deployment
+# gem 'capistrano-rails', group: :development
+
+# Reduces boot times through caching; required in config/boot.rb
+gem "bootsnap", ">= 1.1.0", require: false
+
+group :development, :test do
+  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
+  gem "byebug", platforms: [:mri, :mingw, :x64_mingw]
+end
+
+group :development do
+  # Access an interactive console on exception pages or by calling 'console' anywhere in the code.
+  gem "listen", ">= 3.0.5", "< 3.2"
+  gem "web-console", ">= 3.3.0"
+  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
+  gem "spring"
+  gem "spring-watcher-listen", "~> 2.0.0"
+end
+
+group :test do
+  # Adds support for Capybara system testing and selenium driver
+  gem "capybara", ">= 2.15"
+  gem "selenium-webdriver"
+  # Easy installation and use of chromedriver to run system tests with Chrome
+  gem "chromedriver-helper"
+end
+
+# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
+gem "tzinfo-data", platforms: [:mingw, :mswin, :x64_mingw, :jruby]
+
+gem "sqlite3", "~> 1.4"
+
+gem "rspec-rails", "~> 3.8"
+gem "rspec_junit_formatter"

cloud-sql/postgres/activerecord/README.md

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+# Connecting to Cloud SQL - MySQL
+
+## Before you begin
+
+1. If you haven't already, set up a Ruby Development Environment by following the [ruby setup guide](https://cloud.google.com/ruby/docs/setup) and 
+[create a project](https://cloud.google.com/resource-manager/docs/creating-managing-projects#creating_a_project).
+
+1. Create a 2nd Gen Cloud SQL Instance by following these 
+[instructions](https://cloud.google.com/sql/docs/mysql/create-instance). Note the connection string,
+database user, and database password that you create.
+
+1. Create a database for your application by following these 
+[instructions](https://cloud.google.com/sql/docs/mysql/create-manage-databases). Note the database
+name. 
+
+1. Create a service account with the 'Cloud SQL Client' permissions by following these 
+[instructions](https://cloud.google.com/sql/docs/mysql/connect-external-app#4_if_required_by_your_authentication_method_create_a_service_account).
+Download a JSON key to use to authenticate your connection. 
+
+
+
+## Running locally
+
+Use the information noted in the previous steps:
+```bash
+export GOOGLE_APPLICATION_CREDENTIALS=/path/to/service/account/key.json
+export INSTANCE_CONNECTION_NAME='<MY-PROJECT>:<INSTANCE-REGION>:<INSTANCE-NAME>'
+export DB_USER='my-db-user'
+export DB_PASS='my-db-pass'
+export DB_NAME='my_db'
+```
+Note: Saving credentials in environment variables is convenient, but not secure - consider a more
+secure solution such as [Secret Manager](https://cloud.google.com/secret-manager/docs/overview) to help keep secrets safe.
+
+Then, download and install the `cloud_sql_proxy` by
+following the instructions
+[here](https://cloud.google.com/sql/docs/mysql/authorize-proxy#installing_the). Once the
+proxy has been downloaded, use the following commands to create the `/cloudsql`
+directory and give the user running the proxy the appropriate permissions:
+```bash
+sudo mkdir /cloudsql
+sudo chown -R $USER /cloudsql
+```
+
+Once the `/cloudsql` directory is ready, use the following command to start the proxy in the
+background:
+```bash
+./cloud_sql_proxy -dir=/cloudsql --instances=$INSTANCE_CONNECTION_NAME --credential_file=$GOOGLE_APPLICATION_CREDENTIALS
+```
+Note: Make sure to run the command under a user with write access in the 
+`/cloudsql` directory. This proxy will use this folder to create a unix socket
+the application will use to connect to Cloud SQL. 
+
+Next, setup install the requirements:
+```bash
+bundle install
+```
+
+Then, setup and seed the database:
+```bash
+bundle exec rails db:setup
+bundle exec rails db:seed
+```
+
+Finally, start the application:
+```bash
+bundle exec rails s
+```
+
+Navigate towards `http://localhost:3000` to verify your application is running correctly.
+
+## Deploy to Google App Engine Standard
+
+To allow your app to connect to your Cloud SQL instance when the app is deployed, add the user, password, database, and instance connection name variables from Cloud SQL to the related environment variables in the `app.standard.yaml` file. The deployed application will connect via unix sockets.
+
+    ```
+    env_variables:
+      DB_USER: MY_DB_USER
+      DB_PASS: MY_DB_PASSWORD
+      DB_NAME: MY_DATABASE
+      # e.g. my-awesome-project:us-central1:my-cloud-sql-instance
+      CLOUD_SQL_CONNECTION_NAME: <MY-PROJECT>:<INSTANCE-REGION>:<MY-DATABASE>
+    ```
+
+SECRET_KEY_BASE can be found by running:
+```bash
+bundle exec rails secret
+```
+
+To deploy to App Engine Standard, run the following command:
+```bash
+gcloud app deploy app.standard.yaml
+```
+
+
+## Google App Engine Flexible
+
+To run on GAE-Flex, create an App Engine project by following the setup for these 
+[instructions](https://cloud.google.com/appengine/docs/flexible/ruby/quickstart).
+
+First, update `app.flexible.yaml` with the correct values to pass the environment 
+variables into the runtime.
+
+SECRET_KEY_BASE can be found by running:
+```bash
+bundle exec rails secret
+```
+
+To deploy to App Engine Flexible, run the following command:
+```bash
+gcloud app deploy app.flexible.yaml
+```

cloud-sql/postgres/activerecord/Rakefile

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+# Add your own tasks in files placed in lib/tasks ending in .rake,
+# for example lib/tasks/capistrano.rake, and they will automatically be available to Rake.
+
+require_relative "config/application"
+
+Rails.application.load_tasks

cloud-sql/postgres/activerecord/app.flexible.yaml

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+# Copyright 2020 Google, Inc
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+entrypoint: bundle exec rackup --port $PORT
+env: flex
+runtime: ruby
+
+env_variables:
+  SECRET_KEY_BASE: [SECRET_KEY]
+  RAILS_ENV: production
+  INSTANCE_CONNECTION_NAME: [<MY-PROJECT>:<INSTANCE-REGION>:<INSTANCE-NAME>]
+  DB_USER: [MY_DB_USER]
+  DB_PASS: [MY_DB_PASS]
+  DB_NAME: [MY_DB]
+
+beta_settings:
+  cloud_sql_instances: [YOUR_INSTANCE_CONNECTION_NAME]

cloud-sql/postgres/activerecord/app.standard.yaml

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+# Copyright 2020 Google, Inc
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+entrypoint: bundle exec rackup --port $PORT
+runtime: ruby25
+
+env_variables:
+  SECRET_KEY_BASE: [SECRET_KEY]
+  RAILS_ENV: production
+  INSTANCE_CONNECTION_NAME: [<MY-PROJECT>:<INSTANCE-REGION>:<INSTANCE-NAME>]
+  DB_USER: [MY_DB_USER]
+  DB_PASS: [MY_DB_PASS]
+  DB_NAME: [MY_DB]
+
+beta_settings:
+  cloud_sql_instances: [YOUR_INSTANCE_CONNECTION_NAME]

cloud-sql/postgres/activerecord/app/assets/config/manifest.js

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+//= link_tree ../images
+//= link_directory ../javascripts .js
+//= link_directory ../stylesheets .css

cloud-sql/postgres/activerecord/app/assets/images/.keep

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+// This is a manifest file that'll be compiled into application.js, which will include all the files
+// listed below.
+//
+// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, or any plugin's
+// vendor/assets/javascripts directory can be referenced here using a relative path.
+//
+// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
+// compiled file. JavaScript code in this file should be added after the last require_* statement.
+//
+// Read Sprockets README (https://github.com/rails/sprockets#sprockets-directives) for details
+// about supported directives.
+//
+//= require rails-ujs
+//= require activestorage
+//= require turbolinks
+//= require_tree .

cloud-sql/postgres/activerecord/app/assets/javascripts/application.js

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+// Action Cable provides the framework to deal with WebSockets in Rails.
+// You can generate new channels where WebSocket features live using the `rails generate channel` command.
+//
+//= require action_cable
+//= require_self
+//= require_tree ./channels
+
+(function() {
+  this.App || (this.App = {});
+
+  App.cable = ActionCable.createConsumer();
+
+}).call(this);