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

Swarm’s orchestrator schedules containers (or more strictly, tasks to run containers) on whichever nodes it sees fit. That means
we don’t know where a container for service will end up running.

# Visualizer
For educational purposes, we are going to use a new “visualizer” tool that provides a web interface for seeing the nodes in our clusters, and the containers running on them. Docker provides a handy image for this. You wouldn’t typically run the visualizer in production, but it will give us a feel for how containers are scheduled across the cluster.

## Modifying Stack file

Let’s add a visualizer service to our `docker-stack.yml` file:

visualizer:
  image: dockersamples/visualizer:stable
  ports:
	- "8080:8080"
  volumes:
    - "/var/run/docker.sock:/var/run/docker.sock"
  deploy:
    placement:
      constraints: [node.role == manager]

In order to view the web interface, we need to expose a port publicly. Internally, the visualizer runs on port 8080. Since nothing else in our cluster runs on this
port, we have chosen to use it as the public port we expose (**lines 3–4)**.

The visualizer relies on having access to a file called **/var/run/docker.sock**, which is available on the Dockerhost. We mount it into the container as a volume (**line 6**).


> ### For the Curious: ‘/var/run/docker.sock‘
>The **/var/run/docker.sock** file is a socket created by the Docker daemon
to allow other processes to communicate with it via a (mostly) RESTful API.
We can use curl to try it out. For example:
>```text
>$ SOCKET=/var/run/docker.sock
>$ ENDPOINT=http:/v1.37/containers/json
>$ docker-machine ssh do-manager-1 \
 >     "curl --unix-socket $SOCKET $ENDPOINT"
>```
>You should see JSON output listing the various containers.

Next, come **lines 7–9**. We haven’t seen the `deploy` attribute for service before. Swarm uses attributes under this to specify various deployment-related configuration options. Here we specify what is known as a placement constraint:`[node.role == manager]`.

This says, “Only deploy this service to nodes acting as a swarm manager.” This is necessary because only a swarm manager will have the full information about the swarm that the visualizer needs to display.

To deploy the new visualizer service to our swarm, run:
```text
$ docker stack deploy -c docker-stack.yml myapp
```

Wait until the visualizer is running—the following command will show replicas “1/1” for the visualizer service when it is:



Learn about visualizers and how to add them to your stack file to view.

Visualizing Containers

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

Visualizing Containers

Visualizer