Slides from Ansible Oxford meetup on 29th July 2015: Cows and Containers. How does Ansible play with Docker? How can we use Ansible to build, ship and run Docker containers?

1. Ansible Oxford
Cows and Containers
29th July 2015
DevSpace/Hatch/old Barclays, Oxford

2. Ansible
Runs a TASK on a HOST

3. Problem:
How do I configure my
servers and services?

4. Solution:
Write playbooks with tasks,
bundle into roles and run
against your hosts localhost for
services

5. Docker
Virtualised OS

6. New problems:
How do I build my Dockerimages?
How do I run my containers?
How do I ship them?

7. First stab
Write a Dockerfile (basically a shell
script written as a children's book)
RUN apt-get update
RUN apt-get –y install awesome
COPY myfile /tmp/

8. “works”
Time spent troubleshooting
counted in days
Revert back to shell commands for
configuration

9. Build with
Ansible

10. Dockerfile:
1. Install Ansible
2. Copy over/git clone Ansible project
3. Run Ansible playbook against localhost

11. Pros:
- Re-use existing playbooks
- Portability (VM!container)
Cons:
- Ansible installed in container

12. $ cat myapp/Dockerfile
FROM ubuntu:14.04
MAINTAINER jonatanblue version: 0.3
# Install Ansible
RUN apt-get -y update && apt-get install -y software-properties-common
RUN echo | apt-add-repository ppa:ansible/ansible
RUN apt-get -y update && apt-get -y install ansible
# Copy over playbook
COPY moo/container.yml /tmp/
# Run playbook
RUN ansible-playbook /tmp/container.yml

13. - name: build image
docker_image:
name: “jonatanblue/myapp:0.3”
OR ( if because above is still a bit unstable)
$ cd myapp
$ docker build --tag=“jonatanblue/myapp:0.3” .

14. Run with Ansible
* “Static” workloads – docker module
* Distributed applications
– … it’s complicated

15. docker module
- name: my app
docker:
name: myapp
image: jonatanblue/myapp:0.3
command: /usr/bin/myapp --mode awesome

16. Distributed applications
• Scheduling
• Active orchestration

17. Active orchestration
1. Resources (busy, free, time to
release, control)
2. Running containers
3. Application health
• Act on this information
• Automatic control problem != trivial

18. Example on AWS
Server1: 2 of 4 cores & 6 of 8GB RAM free
Server2: 4 of 4 cores & 8 of 8GB RAM free
Requirements
Container1: 1core, 1GB
Other stats:
No containers started in last hour, historical data suggests
off-peak period
! Launch container on server1 and terminate server2

19. Mesos - a single pool of resources
http://mesos.apache.org/
Kubernetes - orchestration system
http://kubernetes.io/

20. 2 observations
• Applications to manage Docker
(deployed by Ansible)
• Docker in docker in docker… Registry
great example (built & started by
Ansible)

21. •Build image
•?
•Run container

22. Ship with Ansible

23. • Easy method ! DockerHub
– Public (pay for private)
• Full control ! Registry
– Open source version free
– (pay for enterprise version)

24. • Build image (Ansible playbooks +
docker_image)
• Push to registry (Ansible command
module)
• Run container (Ansible docker module)
Private Registry

25. Jonatan Bjork
DevOps Engineer
@jonatanblue