Ansible Basics

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WHAT YOU WILL LEARN

Ansible is capable of handling many powerful automation tasks with the flexibility to adapt to many environments and workflows. With Ansible, users can very quickly get up and running to do real work.

In this presentation, we will cover:

What is Ansible
How Ansible Works
Ad-Hoc Commands
Playbook Basics
Reuse and Redistribution of Ansible Content with Roles
Ansible Tower

WHAT IS ANSIBLE AUTOMATION?

The Ansible project is an open source community sponsored by Red Hat. It’s also a simple automation language that perfectly describes IT application environments in Ansible Playbooks.

Ansible Engine is a supported product built from the Ansible community project.

Ansible Tower is an enterprise framework for controlling, securing, managing and extending your Ansible automation (community or engine) with a UI and RESTful API.

WHY ANSIBLE?

THE ANSIBLE WAY

CROSS PLATFORM – Linux, Windows, UNIX
Agentless support for all major OS variants, physical, virtual, cloud and network.

HUMAN READABLE – YAML
Perfectly describe and document every aspect of your application environment

PERFECT DESCRIPTION OF APPLICATION
Every change can be made by playbooks, ensuring everyone is on the same page.

VERSION CONTROLLED
Playbooks are plain-text. Treat them like code in your existing version control.

DYNAMIC INVENTORIES
Capture all the servers 100% of the time, regardless of infrastructure, location, etc.

ORCHESTRATION THAT PLAYS WELL WITH OTHERS – HP SA, Puppet, Jenkins, RHNSS, etc.
Homogenize existing environments by leveraging current toolsets and update mechanisms.

BATTERIES INCLUDED

Ansible comes bundled with hundreds of modules for a wide variety of automation tasks:

cloud
containers
database
files
messaging
monitoring
network

notifications
packaging
source control
system
testing
utilities
web infrastructure

COMMUNITY

THE MOST POPULAR OPEN-SOURCE AUTOMATION COMMUNITY ON GITHUB

34,000+ stars & 13,500+ forks on GitHub
4000+ GitHub Contributors
Over 2000 modules shipped with Ansible
New contributors added every day
1400+ users on IRC channel
World-wide meetups taking place every week
Ansible Galaxy: over 9,000 contributors and 18,000 roles
500,000+ downloads a month
AnsibleFests, Ansible Automates, and other global events

ANSIBLE: COMPLETE AUTOMATION

WHAT CAN I DO WITH ANSIBLE?

Automate the deployment and management of your entire IT footprint.

INSTALLING ANSIBLE


# the most common and preferred way of installation
$ pip install ansible

# install the epel-release RPM if needed on CentOS, RHEL, or Scientific Linux
$ sudo yum install ansible

# you will need the PPA repo configured
$ sudo apt-get install ansible

HOW ANSIBLE WORKS

MODULES

Modules are bits of code transferred to the target system and executed to satisfy the task declaration.

apt/yum
copy
file
get_url
git
ping
debug

service
synchronize
template
uri
user
wait_for
assert

MODULES

https://docs.ansible.com/ansible/latest/modules/modules_by_category.html

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. 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

On this slide we’re gonna discuss the command and shell modules which are super useful because you can execute commands with them on your remote nodes. The only big difference is that the command is not processed through the shell so redirect options and certain variables won’t work. If you need those, just use the shell module instead. The command modules let you run networking commands with Ansible, the same way a network engineer would type them on the command line. If you have something that’s not a core module or you haven't written a custom one, you can utilize the script module. For example, if you want to push out a homegrown script, you can do that here. We also have the raw module, which issues a pure SSH command and bypasses the python module mechanism. This is handy if you’re talking to a machine that doesn’t have python (for example, a server that’s running Windows!).

AD-HOC COMMANDS


            # check all my inventory hosts are ready to be managed by Ansible
            $ ansible all -m ping

            # run the uptime command on all hosts in the web group
            $ ansible web -m command -a “uptime”

            # collect and display the discovered for the localhost
            $ ansible localhost -m setup

We’re going to transition right into ad-hoc commands from the commands modules because often times, you utilize command/shell to issue one-off commands to your hosts. This is essentially what ad-hoc commands are; just quick checks on your servers that you don’t want to preserve in an Ansible playbook. The examples here are pretty typical. Our first example is just checking whether we have connectivity with the host by issuing the ping command (I do this all the time to make sure everything is responding). In the second example here, you can see the command to check the uptime on the two servers in my web group using the command module. And lastly, the third example is gathering facts about our local machine which would yield the information that you can use for conditionals and variables and whatnot. [a bit of the output is shown on next slide]

SIDEBAR: DISCOVERED FACTS


$ 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"
    	},

INVENTORY

Inventory is a collection of hosts (nodes) against which Ansible can work with.

Hosts
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

STATIC INVENTORY EXAMPLE


            [control]
            control ansible_host=10.42.0.2

            [web]
            node-1 ansible_host=10.42.0.6
            node-2 ansible_host=10.42.0.7
            node-3 ansible_host=10.42.0.8

            [haproxy]
            haproxy ansible_host=10.42.0.100

            [all:vars]
            ansible_user=vagrant
            ansible_ssh_private_key_file=~/.vagrant.d/insecure_private_key

STATIC INVENTORY EXAMPLE IN YAML


            all:
              vars:
                ansible_user: vagrant
                ansible_ssh_private_key_file: ~/.vagrant.d/insecure_private_key

              children:
                web:
                  hosts:
                    node-1:
                      ansible_host: 10.42.0.6
                    node-2:
                      ansible_host: 10.42.0.7
                    node-3:
                      ansible_host: 10.42.0.8

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

VARIABLE PRECEDENCE

The order in which the same variable from different sources will override each other:

Extra vars
Set_facts/Registered vars
Include_vars
Include_params
Role params
Task vars (only for the task)
Block vars (only for tasks in the block)
Role vars
Play vars_files
Play vars_prompt
Play vars

Host facts
Playbook host_vars
Inventory host_vars
Inventory file/script host vars
Playbook group_vars
Inventory group_vars
Playbook group_vars/all
Inventory group_vars/all
Inventory file or script group vars
Role defaults

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: add cache in directory
  file:
    path: /opt/cache
    state: directory

- name: install nginx
  yum:
    name: nginx
    state: latest

- name: restart nginx
  service:
    name: nginx
    state: restarted

HANDLER TASKS

Handlers are special tasks that run at the end of a play if notified by another task.

EXAMPLE HANDLER IN A PLAY


tasks:
  - name: add cache dir
	 file:
      path: /opt/cache
      state: directory

  - name: install nginx
    yum:
      name: nginx
      state: latest
    notify: restart nginx

handlers:
  - name: restart nginx
    service:
      name: nginx
      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
  vars:
    http_port: 80
    max_clients: 200
  remote_user: root

  tasks:
  - name: install httpd
    yum: pkg=httpd state=latest
  - name: write the apache config file
    template: src=/srv/httpd.j2 dest=/etc/httpd.conf
  - name: start httpd
    service: name=httpd state=started

ROLES

Roles are a packages of closely-related Ansible content that can be shared more easily than plays alone.

PLAYBOOK EXAMPLE


site.yml
roles/
   common/
     files/
     templates/
     tasks/
     handlers/
     vars/
     defaults/
     meta/
   webservers/
     files/
     templates/
     tasks/
     handlers/
     vars/
     defaults/
     meta/

PLAYBOOK WITH ROLES EXAMPLE


# site.yml
---
- hosts: web
  roles:
     - common
     - webservers

ANSIBLE GALAXY

WHERE TO FIND PLAYBOOK EXAMPLES

General Examples:

https://github.com/ansible/ansible-examples

Lightbulb:

https://github.com/ansible/lightbulb/tree/master/examples

Ansible + Vagrant:

https://github.com/geerlingguy/ansible-vagrant-examples

WHERE TO FIND PLAYBOOK EXAMPLES

Would you like to learn Ansible? It’s easy to get started:

ansible.com/get-started

Have you used Ansible already? Try Tower for free:

ansible.com/tower-trial

Want to learn more?

ansible.com/whitepapers

Demo Time!

Show a playbook written out? Show roles? Tower?

Ansible Basics

WHAT YOU WILL LEARN

WHAT IS ANSIBLE AUTOMATION?

WHY ANSIBLE?

THE ANSIBLE WAY

BATTERIES INCLUDED

COMMUNITY

ANSIBLE: COMPLETE AUTOMATION

WHAT CAN I DO WITH ANSIBLE?

INSTALLING ANSIBLE

HOW ANSIBLE WORKS

MODULES

MODULES

MODULES: RUN COMMANDS

AD-HOC COMMANDS

SIDEBAR: DISCOVERED FACTS

INVENTORY

STATIC INVENTORY EXAMPLE

STATIC INVENTORY EXAMPLE

STATIC INVENTORY EXAMPLE IN YAML

VARIABLES

VARIABLE PRECEDENCE

TASKS

EXAMPLE TASKS IN A PLAY

HANDLER TASKS

EXAMPLE HANDLER IN A PLAY

PLAYS & PLAYBOOKS

PLAYBOOK EXAMPLE

ROLES

PLAYBOOK EXAMPLE

PLAYBOOK WITH ROLES EXAMPLE

ANSIBLE GALAXY

WHERE TO FIND PLAYBOOK EXAMPLES

WHERE TO FIND PLAYBOOK EXAMPLES

Demo Time!

Show a playbook written out? Show roles? Tower?

Thank You!