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

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cdToUsercode

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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

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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 self-regulation

Services running on Swarm are self-regulating. We define the desired state for service in terms of the number of containers that should run for it, and Swarm acts to ensure that this state is achieved and maintained.

It is this self-regulation that is key to how scaling is implemented, as well as Swarm’s self-healing properties.

# Swarm as orchestrator

Swarm is made up of different parts. We can consider one part to be the **orchestrator**. Having told Swarm to deploy a service, the orchestrator is
responsible for determining whether the service is in the desired state and,
if not, taking action to correct this.

If the orchestrator sees that an additional container is needed, it creates a
task, which represents the desire for a container to exist. It then sees what
nodes are available in the cluster, and allocates the task to a node.

In our single-node cluster, the orchestrator has no choice but to allocate all of the tasks onto our only node. However, you can imagine that in a multinode setup, tasks could be allocated evenly across multiple instances in the cluster.

Nodes in the cluster check with the orchestrator to know what tasks they have been allocated. They are then responsible for creating one container per task, thus achieving the desired state of the system. An example should make this clearer. When our `web` service was deployed, the number of replica containers needed was also not specified, so the default of one
was assumed. 

The orchestrator sees that we want one `web` service container running, but that, initially, none are. It creates a task for the `web` service and assigns it to our node. The node sees that it has been allocated a `web` service task, and it launches a web container, meeting our desired state.

We can list the tasks in a stack with the following command:

Tasks and Swarm’s Scaling Model

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

Tasks and Swarm’s Scaling Model

Swarm’s self-regulation