• Most of the benefits of Virtual Machines
• Isolated applications
• Portable
• Far more lightweight than Virtual Machines
• Faster development
• Less resource intensive in production
• Compatibility layer for the cloud
• Easily hosted outside of the cloud

• All of the benefits of configuration management
• Automated
• Reliable
• Describes an environment
• Simple
• Agentless
• Uses SSH

docker run \
-v "/mysql/etc:/etc/mysql" \
-v "/mysql/lib:/var/lib/mysql" \
-p "3306:3306" \
jamiemccrindle/mariadb  --wsrep-new-cluster 

• Check to see if we have a data directory
• If we don't, we need to configure the database
• Run mysql_install_db
• Run mysql_safe in the background
• Wait for mysql to come up by polling
• Run an init script to create an admin user
• Shut the database down (because we want it running in the foreground)
• Start up the database in the foreground

if [ ! -f /var/lib/mysql/ibdata1 ]; then
    mysql_install_db
    /usr/bin/mysqld_safe $@ &
    sleep 2
    while : ; do
        echo 'select 1' | mysql
        if [ $? -eq 0 ] ; then
          break
        fi
        sleep 1
    done
    cat /etc/mysql/init.sql | mysql
    /usr/bin/mysqladmin shutdown  
fi
/usr/bin/mysqld_safe $@  

Misconception: If I use Docker then I don't need a configuration management (CM) tool!

• https://github.com/jamiemccrindle/docker_ansible_build
  
• https://github.com/jamiemccrindle/docker_ansible_app
  

1. Installs the latest version of Docker
2. Installs Ansible
3. Installs Java
4. Installs a Private Docker Repository
5. Installs and configures Jenkins
6. Adds Jenkins Job to build our application
7. The Jenkins Job
1. Compiles the application
2. Builds a docker image
3. Pushes the docker image to the docker repository
4. Runs and tests the new docker

package main

import (
    "fmt"
    "net/http"
)

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
			fmt.Fprintf(w, "Hello World!")
		})
	http.ListenAndServe(":8000", nil)
}

FROM google/golang

WORKDIR /gopath/src/app
ADD . /gopath/src/app/
RUN go get app

EXPOSE 8000

CMD []
ENTRYPOINT ["/gopath/bin/app"]

.
├── Vagrantfile
├── ansible.cfg
├── build.yml
├── build_docker_ansible_app.yml
├── deploy.yml
├── inventory
│   └── vagrant_build
│       └── hosts
└── roles
    ├── ansible
    ├── build_docker_ansible_app
    ├── docker_environment
    ├── docker_registry
    ├── java
    ├── jenkins
    ├── jenkins_deploy_keys
    ├── jenkins_jobs
    └── known_hosts_github

- hosts: builder
  sudo: yes
  connection: ssh

  pre_tasks:
    - lineinfile: line='127.0.0.1 docker-registry.example.com' dest=/etc/hosts

  roles:
    - role: docker_environment
    - role: known_hosts_github
    - role: ansible
    - role: docker_registry
    - role: java
    - role: jenkins
      tags: ['jenkins']
    - role: jenkins_jobs
      tags: ['jenkins_jobs']

---

- command: docker build -t docker-registry.example.com:5000/docker_ansible_app ../docker_ansible_app

- command: docker push docker-registry.example.com:5000/docker_ansible_app

- docker: image=docker-registry.example.com:5000/docker_ansible_app ports="8000:8000" name="docker_ansible_app" state=running 

---
- name: check if job exists
  action: command java -jar {{ jenkins.cli_dest }} -s http://localhost:8080 list-jobs
  register: tasks_installed

- name: copy config
  copy: src="{{ job_name }}.xml" dest=/tmp/config.xml

- name: install task
  action: shell java -jar {{ jenkins.cli_dest }} -s http://localhost:8080 create-job {{ job_name }} < /tmp/config.xml
  when: tasks_installed.stdout.find(job_name) == -1

- name: update task
  action: shell java -jar {{ jenkins.cli_dest }} -s http://localhost:8080 update-job {{ job_name }} < /tmp/config.xml
  when: tasks_installed.stdout.find(job_name) != -1