Introduction to Automated Deployments with Ansible

1 COMPANY CONFIDENTIAL – DO NOT DISTRIBUTE #Dynatrace
System Architects with DevOps / Security Group Meetup, Vienna
18th December 2014
Martin Etmajer, @metmajer, Technology Strategist @ Dynatrace
Introduction to
Automated Deployments with Ansible

• Automated Deployments in Continuous Delivery
• Agent-based vs. Agentless Solution Architectures
• Introduction to Ansible
Agenda

Automated Deployments
in Continuous Delivery

feature cycle time time
Customer Users
Utmost Goal: Minimize Cycle Time

Customer Users
minimize

Customer
This is when you
create value!
minimize

Customer
You
This is when you
create value!
minimize

The definition of a deployment pipeline,
which is at the heart of Continuous Delivery:
“A deployment pipeline is, in essence, an automated implementation
of your application’s build, deploy, test and release process.”
Jez Humble & Dave Farley in Continuous Delivery
“Use machines for what they’re good at, use people for what they’re good at.”
Dave Farley at PIPELINE Conference 2014 @vimeo.com/96173993
The Role of Automation in Continuous Delivery

Manual deployments:
• are slow and prone to human errors
• are neither repeatable nor reliable
• are not consistent across environments
• are done by a few experts: hinders collaboration
• require extensive documentation: often outdated
The Problem with Manual Deployments
We are just not good at it!

Agent-based vs. Agentless
Solution Architectures

Agent-Based Solutions

Agent-Based Deployments (Chef, Puppet)

» Can be used in client-server or client-only modes
» Client must be installed on each host to be provisioned
» Clients have dependencies
» Not laid out for server orchestration by design
(do something on server A, then on server B, etc.)
» Chef and Puppet are widely considered to have a large entrance
barrier and are complex to use

Agentless Solutions

Agentless Deployments (Ansible)

Ansible

» Written and extensible in Python
» Human- and machine-readable configuration (YAML)
» No boot-strapping required on deployment hosts (SSH)
» Statements are executed in the order they were specified
» Simple, easy to ramp up with (think of new employees!)
» Clear and concise documentation
Ansible

Ansible Concepts:
Ad-hoc Commands

Ansible Concepts: Ad-hoc Commands
ansible [-i inventory] <host-pattern> [options]
Examples?
» ansible localhost -m copy –a ‘src=/usr/bin/a dest=/usr/bin/b’
» ansible webserver –a ‘/sbin/reboot’ –f 3
–u deploy ––sudo ––ask–sudo–pass
Module Arguments

Ansible Concepts: Ad-hoc Commands
ansible [-i inventory] <host-pattern> [options]
Examples?
» ansible localhost -m copy –a ‘src=/usr/bin/a dest=/usr/bin/b’
» ansible webserver –a ‘/sbin/reboot’ –f 3
–u deploy ––sudo ––ask–sudo–pass
Processes
User Use sudo
Ask password
interactively

Ansible Concepts:
Inventories

Ansible Concepts: Inventories
» Ansible provisions groups of servers at once
» Groups and hosts are stored in inventory files
» An inventory file is expressed in the INI format

Ansible Concepts: Inventories
# production.ini
[web]
web[0-1].example.com
[frontends]
frontend.example.com
[backends]
backend.example.com
Group
Host

Ansible Concepts:
Playbooks

Ansible Concepts: Playbooks
ansible-playbook [–i <inventory>] <playbook>
Playbooks
» describe policies your remote systems shall enforce
» consist of variables, tasks, handlers, files and roles
» are expressed in the YAML format

--- # webservers.yml
- hosts: web
vars_files:
- variables.yml
handlers:
- name: reload apache2
service: name=apache2 state=reloaded
tasks:
- name: Install Apache HTTP Server
apt: name=apache2 update_cache=yes
- name: Install Apache Modules
apache2_module: name={{ item }} state=present
with_items:
- proxy
- proxy_httpd
notify: reload apache2
Play
Module

...
- name: Install Apache Configuration
template: >
src=apache-config.conf.j2
dest={{ apache_conf_home }}/myapp
mode=0644
notify: reload apache2
remote_user: deploy
sudo: yes

--- # variables.yml
apache_conf_home: /etc/apache2/conf.d

--- # playbook.yml
- include: appservers.yml
- include: dbservers.yml
- include: webservers.yml
Includes multiple plays
into a single playbook

ansible-playbook –i production.ini webservers.yml
PLAY [web]
******************************************************
TASK: [Install Apache HTTP Server]
************************
changed: [web0.example.com]
changed: [web1.example.com]
...
PLAY RECAP
************************************************************************
web0.example.com : ok=3 changed=3 unreachable=0 failed=0
web1.example.com : ok=3 changed=3 unreachable=0 failed=0
Run!

Ansible Modules Library

Ansible Modules Library
» Cloud: AWS, Azure, DigitalOcean, Docker, Google, OpenStack,...
» Database: MySQL, Postgresql,...
» Packaging: apt, yum, easy_install, npm, homebrew, zypper,...
» Source Control: git, subversion, mercurial,...
» Web Infrastructure: apache2_module, jira,...
» System: mount, selinux, ufw, user,...

Ansible Concepts: Roles (Outlook)

Ansible Concepts: Playbooks » Roles
Roles
» Are the preferred means to organize and reuse related tasks
» Build on the idea of include files to form clean abstractions
» Can be shared and found on Ansible Galaxy

Ansible Concepts: Playbooks » Roles
Reusing Roles in a Play
--- # webservers.yml
- hosts: web
roles:
- { role: common }
- { role: apache2 }
remote_user: deploy
sudo: yes

Introduction to Automated Deployments with Ansible

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