AWS_ACCESS_KEY_ID

AWS_SECRET_ACCESS_KEY

AWS_DEFAULT_REGION

INTERNAL_IP

IP_PORT

SWARM_TOKEN

BUCKET

DIGITAL_OCEAN_TOKEN

Gain insights into Docker architecture, images, and containers. Delve into Docker Compose, JS integration, and production readiness. Master deploying, clustering, and scaling Rails apps using Docker tools.

tarball.tar.gz

simpleJob

simpleJob2

simpleJob-copy

viewImages

dockerCompose1

challenge1

dockerComposeRedis1

dockerComposeRedis2

dockerComposeRedis3

cdToUsercode

delGitCopyUpCreate

delGitCopyUp

delGitCopyUpMigrate

webPackerCh7

RSpec-Ch8

RSpec-Ch8_2

RSpec-Ch8_2_1

RSpec-Ch8_3

runRailsUsingCustomImage

dockerCompose1-copy

RSpec-Ch8_2-copy

delGitCopyUp-copy

RSpec-Ch8_5

RSpec-Ch8_6

RSpec-Ch8_6_GUI

dockerCompose1-copy-copy

dockerComposePostgres1

webPackerCh7-copy

postgress_last_lesson

Ch12_2

postgress_2nd_last_lesson

Ch12_3

gem_1

gem_2

irritation_1

irritation_1_1

Ch12_1

webPackerCh7_2

Cloud

Cloud_DO

Cloud_1

Cloud_2_1

Cloud_2_2

Cloud_2_4

RSpec-Ch8_2_new

RSpec-Ch8_7

Cloud_1_1_bucket

dockerComposeRedis3-copy

dockerComposeRedis2-copy

Cloud_DO_2

chap4_1

chap5_3

chap5_4

challenge

simpleJob2-ForceRelaunch

simpleJob-ForceRelaunch

RSpec-Ch8_5-copy

dockerCompose1-copy-copy-copy

testing

chap4_1-copy

chap5_3-copy

chap5_4-copy

dockerComposeRedis3-copy-iwrz0a

postgress_2nd_last_lesson-copy

postgress_last_lesson-copy

webPackerCh7_2-copy

This course is your field manual for building Rails applications with Docker. 

To kick things off, you’ll start by learning the basics of Docker like architecture, images, and containers. You will then be introduced to Docker Compose and use it to build up to a multiservice application with Redis.

You will then work to get your Dockerized setup to play nice with JavaScript, using both the standard asset pipeline and webpacker, Rails’ newest approach for integrating modern JavaScript front ends.

Lastly, you will learn how to prepare your Rails app for production. Once ready, using Docker’s own tools, you will provision machines, create a cluster, deploy the app, and scale the app’s resources to meet its changing needs.

By the end of the course, you will be able to confidently use Docker in any of your further projects.

Docker for Rails Developers

# webpack-dev-server
As part of Webpacker, Rails provides the webpack-dev-server binary. This is a small server that runs in the background, automatically compiling our webpack-managed files.

If you were developing locally, this would just be another command you would
issue from your terminal. However, the Docker way is to run this as a separate
service in its own container.

# Modification of Compose 
Let’s add a new service for it to our docker-compose.yml file:



version: '3'
services:
  web:
      build: .
      ports:
           - "3000:3000"
      volumes:
           - .:/usr/src/app
      env_file:
           - .env/development/database
           - .env/development/web
      environment:
           - WEBPACKER_DEV_SERVER_HOST=webpack-dev-server
  webpack-dev-server:
      build: .
      command: ./bin/webpack-dev-server
      ports:
           - 3035:3035
      volumes:
           - .:/usr/src/app
      env_file:
           - .env/development/web
           - .env/development/database
      environment:
           - WEBPACKER_DEV_SERVER_HOST=0.0.0.0
  redis:
      image: redis
  database:
      image: postgres
      env_file:
           - .env/development/database
      volumes:
           - db_data:/var/lib/postgresql/data
volumes:
    db_data:

## Explanation 

* The Rails `webpack_dev_server` is designed to work in the root of your Rails application. That is why we build from the same Dockerfile (**line 15**) as our web service.

* Although it uses the same image and code, we start our new service with a different command. Instead of starting the Rails server, we run the 
`./bin/webpack-dev-server` command itself (**line 16**).

* We expose the service on `webpack-dev-server`’s default port of 3035 (**line 18**).

* We want the `webpack-dev-server` to pick up and recompile our changes automatically as we develop locally without having to restart. That’s why on **lines 19-20**, like in our `web` service, we mount our local files into the container. 

* The `webpack-dev-server` command expects to be run with the same configuration as our Rails app. Luckily, having extracted these into files, we can simply reuse the same env_files (**lines 21-23**).

* However, to ensure that `webpacker-dev-server` listens on all IP addresses, we set `WEBPACKER_DEV_SERVER_HOST` to `0.0.0.0` (**line 25**), much like we did
with the Rails server. 

* Having configured our `webpack_dev_server` service, we also need to set a Rails environment variable for our `web` service so it knows where to find the `webpack-dev-server` (**line 13**).



# 🍀 Practice

Now we need to start our web service to use our new image and pick up these
config changes and then launch our new service:
```text
$ docker-compose up -d web
$ docker-compose up -d webpack-dev-server
```

Try them in the terminal below after clicking the Run button.

> **Note:** The application will be up in a minute. Please start running the commands once you see this message: **_"You may begin now..."_**.

We will learn to add Webpacker in our Compose.

Compiling Assets with Webpacker

Introduction

A Brave New World

Running a Rails App in a Container

Fine-Tuning Our Rails Image

Describing Our App Declaratively with Docker Compose

Beyond the App: Adding Redis

Docker for Rails Developer—Exam 1

Adding a Database: Postgres

Playing Nice with JavaScript

Testing in a Dockerized Environment

Advanced Gem Management

Some Minor Irritations

Docker for Rails Developer—Exam 2

The Production Landscape

Preparing for Production

A Production-Like Playground

Deploying to the Cloud

Docker for Rails Developer - Exam 3

Closing Thoughts and Next Steps

APPENDIX

Compiling Assets with Webpacker

webpack-dev-server