Simple Local Orchestration

Using Docker_Rack Gem

To start a bunch of containerized web services manually requires a lot of work. We can simplify it by using docker_rack gem.

Preparing for Docker_Rack

Install latest ruby (>= ruby 2.2.3p173)
Run bundle install in the dev-environment folder. This will install docker_rack gem and all it’s prerequisites

Discovering available tasks

$ docker_rack list
container:accounts-service:help          # Tasks help for container:accounts-service
container:config-service:help            # Tasks help for container:config-service
container:demo-mongo:help                # Tasks help for container:demo-mongo
container:demo-mysql:help                # Tasks help for container:demo-mysql
container:eureka-service:help            # Tasks help for container:eureka-service
container:gateway-service:help           # Tasks help for container:gateway-service
container:profiles-service:help          # Tasks help for container:profiles-service
env:create_profile                       # Populate Profiles-Service with Test data
env:start                                # Start Environment
env:stop                                 # Stop Environment

A task anatomy

Let’s look at one of the container templates:

dev-environment/container_templates/eureka-service.erb.yml

eureka-service:
  image: msvcdojo/eureka-service:0.0.1
  ports:
    - 8761
  environment:
    config-service.uri: http://<%= dockerhost %>:8888
  checks:
    - port: 8761
      retry: 15
    - uri: http://<%= dockerhost %>:8761/eureka/apps
  depends:
    - config-service

Here is the explanation of the sections of this template:

Name Description

Name	Description
image	ID of a docker image
ports	Array of port mappings in the form `- port` or `- port1:port2`
environment	Array of environment variables and their values
checks	Array of post-start checks. Supported `port` and `uri`
depends	Array of dependencies on other containers

image

ID of a docker image

ports

Array of port mappings in the form - port or - port1:port2

environment

Array of environment variables and their values

checks

Array of post-start checks. Supported port and uri

depends

Array of dependencies on other containers

Launching Orchestration

$ docker_rack exec env:start
Executing 'env:start'
Starting: /microservice-dojo/dev-environment/container_templates/mysql.yml
...
Starting: /microservice-dojo/dev-environment/container_templates/mongo.erb.yml
.
Starting: /microservice-dojo/dev-environment/container_templates/config-service.erb.yml
...
Starting: /microservice-dojo/dev-environment/container_templates/eureka-service.erb.yml
...
.
Starting: /microservice-dojo/dev-environment/container_templates/profiles-service.erb.yml
...
Starting: /microservice-dojo/dev-environment/container_templates/accounts-service.erb.yml
...
Starting: /microservice-dojo/dev-environment/container_templates/gateway-service.erb.yml
...

A single '.' (dot) represents an attempt to run a requested check after the launch of command. One line per each check separately.