How to create a new Rails 5 Shopify app with Redis and Sidekiq in Docker

Goals

Create a new Rails 5 app
Use the shopify_app gem for app architecture and API access
Redis and Sidekiq for jobs
Develop locally with the app contained in Docker

Prerequisites

Experience with Ruby and Rails
Updated versions of Ruby, Rails, and Docker.
1. Install Ruby On Rails
2. Get started with Docker
Docker experience
ngrok account created and installed. Get started with ngrok

1. Create a new rails app using postgres as the database

rails new app_name -d postgresql

Be sure to change app_name to your apps name.

2. Set up docker in your new rails app

Add .env to .gitignore

Create .env.template with the following:

COMPOSE_PROJECT_NAME=app_name

RAILS_ENV=development
SECRET_TOKEN=asecuretokenwouldnormallygohere

BIND_ON=0.0.0.0:5000
RAILS_MAX_THREADS=1
WEB_CONCURRENCY=1

DATABASE_URL=postgresql://app_name_development:yourpassword@postgres:5432/app_name_development?encoding=utf8&pool=5&timeout=5000

POSTGRES_DB='app_name_development'
POSTGRES_USER='app_name_development'
POSTGRES_PASSWORD='yourpassword'

REDIS_DEV_URL=redis://redis:6379/0

SHOPIFY_API_KEY=
SHOPIFY_API_SECRET_KEY=
APP_BASE_URL=

assets=precompile

Be sure to change app_name to your apps name in POSTGRES_DB and POSTGRES_USER.

Copy .env.template to .env

The values for SHOPIFY_API_KEY, SHOPIFY_API_SECRET_KEY, and APP_BASE_URL will be updated later.

.env.template is committed to git as a starting point for others to develop locally. .env is ignored from git because it will have API keys and secrets that no one should have access to.

Create .dockerignore with the following:

.byebug_history
.dockerignore
.git
log/*
tmp/*

Create Dockerfile with the following:
```
FROM ruby:2.5.1-alpine

RUN apk update && apk add build-base nodejs postgresql-dev

RUN mkdir /app
WORKDIR /app

COPY Gemfile Gemfile.lock ./
RUN bundle install --binstubs

COPY . .

LABEL maintainer="Able Sense <support@ablesense.com>"

CMD puma -C config/puma.rb
```
This sets up the container for the rails server. It first installs some packages we'll need, copies Gemfile and Gemfile.lock (more on this later), runs bundle install, copies the app into the container, then starts the server.

Using the alpine version of images to reduce size. Alpine has all the features we should need.

Create docker-compose.yml with the following:

version: '3'

services:
  postgres:
    image: 'postgres:10.4-alpine'
    environment:
      POSTGRES_DB: 'shopify_base_app_development'
      POSTGRES_USER: 'shopify_base_app_development'
      POSTGRES_PASSWORD: 'yourpassword'
    volumes:
      - 'postgres:/var/lib/postgresql/data'
    env_file:
      - '.env'

  redis:
    image: 'redis:4.0-alpine'
    command: redis-server
    volumes:
      - 'redis:/data'
    env_file:
      - '.env'

  web:
    depends_on:
      - 'postgres'
      - 'redis'
    build: .
    ports:
      - '3000:3000'
    env_file:
      - '.env'
    volumes:
      - '.:/app'

  sidekiq:
    depends_on:
      - 'postgres'
      - 'redis'
    build: .
    command: sidekiq -C config/sidekiq.yml.erb
    volumes:
      - '.:/app'
    env_file:
      - '.env'

volumes:
  redis: {}
  postgres: {}

Docker compose is used to run our containers and setup any others we may need like postgres, redis, and sidekiq. Each services has some configuration options set to allow the containers to talk to each other. Be sure to change app_name to your apps name.

3. Setup ngrok

Are you using a custom subdomain?

YES?

Log into your ngrok dashboard and go to https://dashboard.ngrok.com/reserved.

If you already have a subdomain reserved find it in the list and copy just the subdomain, leave off the .ngrok.io.

If you haven't already reserved a subdomain then create a new one on that same page.

In your terminal run:
```
ngrok http -subdomain=my-app 3000
```
NO?

In your terminal run:
```
ngrok http 3000
```
Note that if you're not using a reserved subdomain you will have to update the url for your app in the partners dashboard every time you restart ngrok.

Now that ngrok is listening on port 3000 it will list some info. Look for the forwarding address that uses https and copy it for use in the next step.

4. Create a new app in the Shopify partners dashboard

Log into your Shopify Partners dashboard to create a new app. Click here to become a shopify partner if you aren't already signed up.

Find the apps link in the dashboard on the left then click create app. You'll get a popup like this.

Here you will give the app a name, and the URL for your new local app. The URL is the forwarding address that was created in the previous step by ngrok.

Note that if you're not using a reserved subdomain you will have to update the url for your app in the partners dashboard every time you restart ngrok.

5. App configuration for local development

Open .env and update the following
1. COMPOSE_PROJECT_NAME name of your app
2. SHOPIFY_API_KEY provided by shopify after creating a new app
3. SHOPIFY_API_SECRET_KEY provided by shopify after creating a new app
4. APP_BASE_URL the ngrok forwarding URL

Open config/database.yml

Under the development section add the following lines:

database: <%= ENV['POSTGRES_DB'] %>
username: <%= ENV['POSTGRES_USER'] %>
password: <%= ENV['POSTGRES_PASSWORD'] %>

Create config/initializers/sidekiq.rb with the following:

if Rails.env.development?
  Sidekiq.configure_client do |config|
    config.redis = { url: ENV['REDIS_DEV_URL'], size: ENV['SIDEKIQ_CONNECTIONS'] }
  end

  Sidekiq.configure_server do |config|
    config.redis = { url: ENV['REDIS_DEV_URL'] }

    Rails.application.config.after_initialize do
      Rails.logger.info("DB Connection Pool size for Sidekiq Server before disconnect is: #{ActiveRecord::Base.connection.pool.instance_variable_get('@size')}")
      ActiveRecord::Base.connection_pool.disconnect!

      ActiveSupport.on_load(:active_record) do
        ActiveRecord::Base.establish_connection
        Rails.logger.info("DB Connection Pool size for Sidekiq Server is now: #{ActiveRecord::Base.connection.pool.instance_variable_get('@size')}")
      end
    end
  end
end

if Rails.env.production?

  Sidekiq.configure_client do |config|
    config.redis = { url: ENV['REDIS_URL'], size: ENV['SIDEKIQ_CONNECTIONS'] }
  end

  Sidekiq.configure_server do |config|
    config.redis = { url: ENV['REDIS_URL'] }

    Rails.application.config.after_initialize do
      Rails.logger.info("DB Connection Pool size for Sidekiq Server before disconnect is: #{ActiveRecord::Base.connection.pool.instance_variable_get('@size')}")
      ActiveRecord::Base.connection_pool.disconnect!

      ActiveSupport.on_load(:active_record) do
        ActiveRecord::Base.establish_connection
        Rails.logger.info("DB Connection Pool size for Sidekiq Server is now: #{ActiveRecord::Base.connection.pool.instance_variable_get('@size')}")
      end
    end
  end
end

Open Gemfile
- Make sure ruby version is 2.5.1
- add gem 'shopify_app' above the rails gem
- add gem 'sidekiq'
- add gem 'redis', '~> 4.0'
- change gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby] to just be gem 'tzinfo-data'. Our docker container needs to use this gem but by default it is locked down to certain platforms.
Rename Gemfile.lock to Gemfile.lock.old, then create an empty Gemfile.lock

Bundle install will fail inside the docker container if this file was created when creating the rails app on our local machine. We want to let docker create it's own lock file from our updated Gemfile.

6. Build and spin up the docker containers

Now that everything is configured we can build our containers and get them up and running to start working on our app.

run docker-compose build to download the images and build the containers. This may take a few minutes.
in a new terminal start ngrok if it's not already running. ngrok http 3000 or ngrok http -subdomain=my-app 3000
run docker-compose up to get the containers running with the settings from docker-compose.yml
in a new terminal run docker-compose ps to view the status of containers in this project
run docker-compose stop to stop the containers

With ngrok running and all containers up you should be able to open the ngrok forwarding URL in a browser and see the "Yay! You're on Rails!" screen.

7. Shopify app gem setup

There are just a few things left to do to turn our Rails app into a Shopify app. With docker running, start by opening a new terminal.

Generate shopify app. Since we're using environment variables for the app api key and secret we don't want to use the optional arguments for that command.
```
docker-compose exec web rails generate shopify_app:install
```

Create the shop table, model, and controller

docker-compose exec web rails generate shopify_app:shop_model

Run the migrations to create the shop table in the database
```
docker-compose exec web rails db:migrate
```
Generate resources to create a basic page that installed users will see. This page is just an example use of the Shopify API to print out a few products from the store and list the webhooks set up for this app.
```
docker-compose exec web rails generate shopify_app:home_controller
```

Open config/initializers/shopify_app.rb and change the following lines:

config.api_key = ENV['SHOPIFY_API_KEY']
config.secret = ENV['SHOPIFY_API_SECRET_KEY']

8. Get to work

With ngrok running and all containers up you should be able to open the ngrok forwarding URL in a browser and see the shopify app install screen.

Helpful commands

Tail rails logs

docker-compose exec web tail -f log/development.log

Rails commands

docker-compose exec web rails db:migrate

docker-compose exec web rails console

Access postgres from the command line

docker-compose exec postgres psql -U app_name_development

derekmorash/rails-5-shopify-app