Ansible hands-on-introduction

Ansible Hands-on Introduction
Jon Jozwiak, Sr. Cloud Solutions Architect
Minneapolis RHUG - April 13, 2017

What is Ansible?
It's a simple automation language that can perfectly describe
an IT application infrastructure in Ansible Playbooks.
It's an automation engine that runs Ansible Playbooks.
Ansible Tower is an enterprise framework for controlling,
securing and managing your Ansible automation with a UI and
RESTful API.

Community
THE MOST POPULAR OPEN-SOURCE AUTOMATION COMMUNITY ON GITHUB
13,000+ stars & 4,000+ forks on GitHub
2000+ GitHub Contributors
Over 900 modules shipped with Ansible
New contributors added every day
1200+ users on IRC channel
Top 10 open source projects in 2014
World-wide meetups taking place every week
Ansible Galaxy: over 18,000 subscribers
250,000+ downloads a month
AnsibleFests in NYC, SF, London
http://ansible.com/community

Installing Ansible
# Install with yum (Example RHEL 7)
$ wget http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-9.noarch.rpm
$ yum localinstall epel-release-7-9.noarch.rpm
$ yum --enablerepo=epel install ansible
# Install using pip
$ pip install ansible

Modules
Modules are bits of code transferred to the target system and
executed to satisfy the task declaration. Ansible ships with
several hundred today!
apt/yum
copy
file
get_url
git
ping
debug
service
synchronize

Modules Documentation
http://docs.ansible.com/

Modules Documentation
# List out all modules installed
$ ansible-doc -l
...
copy
cron
...
# Read documentation for installed module
$ ansible-doc copy
> COPY
The [copy] module copies a file on the local box to remote locations. Use the [fetch] module to copy files from remote locations to the local
box. If you need variable interpolation in copied files, use the [template] module.
* note: This module has a corresponding action plugin.
Options (= is mandatory):
...

Modules: Run Commands
If Ansible doesn’t have a module that suits your needs there are the “run
command” modules:
command: Takes the command and executes it on the host. The most
secure and predictable.
shell: Executes through a shell like /bin/sh so you can use pipes etc. Be
careful.
script: Runs a local script on a remote node after transferring it.
raw: Executes a command without going through the Ansible module
subsystem.
NOTE: Unlike standard modules, run commands have no concept of desired
state and should only be used as a last resort.

Inventory
Inventory is a collection of hosts (nodes) with associated data and groupings
that Ansible can connect and manage.
Hosts (nodes)
Groups
Inventory-specific data (variables)
Static or dynamic sources

Static Inventory Example
10.42.0.2
10.42.0.6
10.42.0.7
10.42.0.8
10.42.0.100
host.example.com

Static Inventory Example
[control]
control ansible_host=10.42.0.2
[web]
node-[1:3] ansible_host=10.42.0.[6:8]
[haproxy]
haproxy ansible_host=10.42.0.100
[all:vars]
ansible_user=vagrant
ansible_ssh_private_key_file=~/.vagrant.d/insecure_private_key

Ad-Hoc Commands
An ad-hoc command is a single Ansible task to perform quickly, but don’t want
to save for later.
# check all my inventory hosts are ready to be
# managed by Ansible
$ ansible all -m ping
# collect and display the discovered facts
# for the localhost
$ ansible localhost -m setup
# run the uptime command on all hosts in the
# web group
$ ansible web -m command -a "uptime"

Sidebar: Discovered Facts
Facts are bits of information derived from examining a host systems that are
stored as variables for later use in a play.
$ ansible localhost -m setup
localhost | success >> {
"ansible_facts": {
"ansible_default_ipv4": {
"address": "192.168.1.37",
"alias": "wlan0",
"gateway": "192.168.1.1",
"interface": "wlan0",
"macaddress": "c4:85:08:3b:a9:16",
"mtu": 1500,
"netmask": "255.255.255.0",
"network": "192.168.1.0",
"type": "ether"
},

Variables
Ansible can work with metadata from various sources and manage their context
in the form of variables.
Command line parameters
Plays and tasks
Files
Inventory
Discovered facts
Roles

Tasks
Tasks are the application of a module to perform a specific unit of work.
file: A directory should exist
yum: A package should be installed
service: A service should be running
template: Render a configuration file from a template
get_url: Fetch an archive file from a URL
git: Clone a source code repository

Example Tasks in a Play
tasks:
- name: httpd package is present
yum:
name: httpd
state: latest
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
- name: restart httpd
service:
name: httpd
state: restarted

Handler Tasks
Handlers are special tasks that run at the end of a play if notified by another
task when a change occurs.
If a configuration file gets changed notify a service
restart task that it needs to run.

Example Handler Task in a Play
tasks:
yum:
name: httpd
state: latest
notify: restart httpd
copy:
handlers:
- name: restart httpd
service:
name: httpd
state: restarted

Plays & Playbooks
Plays are ordered sets of tasks to execute against host selections from your
inventory. A playbook is a file containing one or more plays.

Playbook Example
---
- name: install and start apache
hosts: web
become: yes
vars:
http_port: 80
tasks:
yum:
name: httpd
state: latest
copy:
- name: httpd is started
service:
name: httpd
state: started

Human-Meaningful Naming
---
hosts: web
become: yes
vars:
http_port: 80
tasks:
yum:
name: httpd
state: latest
copy:
service:
name: httpd
state: started

Host Selector
---
hosts: web
become: yes
vars:
http_port: 80
tasks:
yum:
name: httpd
state: latest
copy:
service:
name: httpd
state: started

Privilege Escalation
---
hosts: web
become: yes
vars:
http_port: 80
tasks:
yum:
name: httpd
state: latest
copy:
service:
name: httpd
state: started

Play Variables
---
hosts: web
become: yes
vars:
http_port: 80
tasks:
yum:
name: httpd
state: latest
copy:
service:
name: httpd
state: started

Tasks
---
hosts: web
become: yes
vars:
http_port: 80
tasks:
- name: latest httpd package is present
yum:
name: httpd
state: latest
copy:
service:
name: httpd
state: started

Doing More with Playbooks
Here are some more essential playbook features that you can apply:
Templates
Loops
Conditionals
Tags
Blocks

Templates
Ansible embeds the that can be used to dynamically:
Set and modify play variables
Conditional logic
Generate files such as configurations from variables
Jinja2 templating engine

Loops
Loops can do one task on multiple things, such as create a lot of users, install a
lot of packages, or repeat a polling step until a certain result is reached.
- yum:
name: "{{ item }}"
state: latest
with_items:
- httpd
- mod_wsgi

Conditionals
Ansible supports the conditional execution of a task based on the run-time
evaluation of variable, fact, or previous task result.
- yum:
name: httpd
state: latest
when: ansible_os_family == "RedHat"

Tags
Tags are useful to be able to run a subset of a playbook on-demand.
- yum:
name: "{{ item }}"
state: latest
with_items:
- httpd
- mod_wsgi
tags:
- packages
- template:
src: templates/httpd.conf.j2
dest: /etc/httpd/conf/httpd.conf
tags:
- configuration

Blocks
Blocks cut down on repetitive task directives, allow for logical grouping of tasks
and even in play error handling.
- block:
- yum:
name: "{{ item }}"
state: latest
with_items:
- httpd
- mod_wsgi
- template:
src: templates/httpd.conf.j2
dest: /etc/httpd/conf/httpd.conf
when: ansible_os_family == "RedHat"

Roles
Roles are a packages of closely related Ansible content that can be shared more
easily than plays alone.
Improves readability and maintainability of complex plays
Eases sharing, reuse and standardization of automation processes
Enables Ansible content to exist independently of playbooks, projects --
even organizations
Provides functional conveniences such as file path resolution and default
values

Project with Embedded Roles Example
site.yml
roles/
common/
files/
templates/
tasks/
handlers/
vars/
defaults/
meta/
apache/
files/
templates/
tasks/
handlers/
vars/
defaults/
meta/

Project with Embedded Roles Example
# site.yml
---
- hosts: web
roles:
- common
- apache

Ansible Galaxy
http://galaxy.ansible.com
Ansible Galaxy is a hub for finding, reusing and sharing Ansible content.
Jump-start your automation project with content contributed and reviewed by
the Ansible community.

Lab #3:
A Playbook Using Roles
Lab #4:
Using an Ansible Galaxy Role

Next Steps
It's easy to get started
ansible.com/get-started
Join the Ansible community
ansible.com/community
Would you like to learn a lot more?
redhat.com/en/services/training/do407-automation-ansible

Ansible hands-on-introduction

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