DevOps introduction with ansible, vagrant, and docker
1. DevOps: What is it and why is it important?
Mark Stillwell
September 28, 2014
2. Traditional Development/Deployment best practices
I source code only in vcs
I static release as versioned archive
I unit testing of code in development environment
I
3. nal product not installed on developer machine
I deployment instructions via howto or interactive application
I time consuming
I dicult to replicate
7. Issues With These Approaches
I Coordination, Communication, Documentation:
I I'll edit the document and email you when I'm done.
I I had to tinker with /etc/foo to get things working.
I Handling of con
icts
I No automating of merges
I Lack of one true authoritative latest version.
I Culture of Fear
I I know generally what needs to be done, but I'm afraid to try
because I might break it and not be able to get things working
again.
9. c Issues
I Diculty verifying complicated interaction between multiple
parts.
I Brittle deployment: It works, mostly, but don't touch it!
I Experts-Only install discourages end-users, results in lower
adoption/mindshare.
10. DevOps
I deployment as code in vcs
I continuously tested
I test environment similar to deployment environment
I enabled by virtual machines and containers
I regular deployments to production
I industry standard practice!
I NetFlix, Etsy, Twitter, etc tear down infrastructure and
redeploy multiple times per day. . .
I culture of fearless development
12. Ansible
I tool for managing distributed software deployments
I similar tools: puppet, chef, salt, cfengine
I free software (for command line, commercial web-based
management interface)
I written in python
I con
14. guration
I really only pseudo-idempotent
I push model that only requires administrator's computer have
ansible software and client machines have sshd and python
I all other require some kind of bootstrapping process on clients
I some (e.g., puppet) require server setup
15. Example Playbook
- hosts: all
sudo: True
tasks:
- name: ensure sysctl is configured
sysctl:
name: vm.swappiness
value: 10
state: present
- name: ensure latest version is installed
apt:
pkg: etckeeper
state: latest
16. Vagrant
I command line wrapper to virtualisation tools like
virtualbox/kvm
I sets up disks / networking etc.
I all con
18. le
I can bring up and network multiple vms with dierent
operating systems
I can invoke provisioning tools like ansible, or shell scripts
I user just needs to cd to right directory, type vagrant up
20. le
Vagrant.configure(2) do |config|
config.vm.box = ubuntu/trusty
config.vm.network forwarded_port, guest: 80, host: 80
config.vm.provider virtualbox do |v|
v.memory = 1280
end
config.vm.provision ansible do |ansible|
ansible.playbook = site.yml
end
end
21. Docker
I interface for managing container based deployments
I light-weight environment virtualisation that makes use of
linux-kernel features
I like chroot on steroids
I currently uses lxc, but this may change in the future
I also manages layered
22. le sytems using aufs copy-on-write
I disk-space ecient
I docker.io has a repository of of layers, e.g. docker pull
ubuntu
I can be used to provide lightweight linux virtual machines,
but this isn't the most ecient approach
I no need to run multiple copies of system services
I preference is one process per container, single responsibility
principle
I inter-process communication enabled by mapping directories /
ports between containers and/or host
