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.
Ansible is...
Simple:
Human readable automation no special coding skills needed tasks executed in order Get productive quicky.
Powerful:
App development configuration management workflow orchestration Orchestrate the app lifecycle
Agentless:
Agentless architecture uses OpenSSH & WinRM No agent to expolit or update More efficient & more secure.
Installing Ansible on Ubuntu 18.04 LTS
$ sudo apt update
$ sudo apt install software-properties-common
$ sudo apt-add-repository --yes --update ppa:ansible/ansible
$ sudo apt install ansibleHow Ansible Work:
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
- template
Module Documentation:
https://docs.ansible.com/ansible/latest/user_guide/modules.html
# 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):
Module: Run Commands
If Ansible doesn't have a module that suits your needs there are the "run command" module:
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.
Inventory:
Inventory is a collection of hosts (nodes) with associated data and groupings that Ansible can connect and manage.
Hosts
Groups
Inventory-specific data (variables)
Static or dynamic sources
Static Inventory Example:
192.168.0.0
192.168.0.1
192.168.0.2
192.168.0.3
host.example.com
Static Inventory Example
[control]
control ansible_host=192.168.0.0
[web]
node-[1:3] ansible_host=192.168.0.[6:8]
[haproxy]
haproxy ansible_host=192.168.0.2
[all:vars]
ansible_user=ubuntu
ansible_ssh_private_key_file=~/
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"
},
Ad-Hoc Commands:
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: apache2 package is present
apt:
name: apache2
state: latest
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
- name: restart apache2
service:
name: apache2
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:
- name: apache2 package is present
apt:
name: apache2
state: latest
notify: restart apache2
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
handlers:
- name: restart apache2
service:
name: apache2
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:
- name: apache2 package is present
apt:
name: apache2
state: latest
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
Human-Meaningful Naming
---
- name: install and start apache
hosts: web
become: yes
vars:
http_port: 80
tasks:
- name: apache2 package is present
apt:
name: apache2
state: latest
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
Host Selector
---
- name: install and start apache
hosts: web
become: yes
vars:
http_port: 80
tasks:
- name: apache2 package is present
apt:
name: apache2
state: latest
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
Privilege Escalation
---
- name: install and start apache
hosts: web
become: yes
vars:
http_port: 80
tasks:
- name: apache2 package is present
apt:
name: apache2
state: latest
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
Play Variables:
---
- name: install and start apache
hosts: web
become: yes
vars:
http_port: 80
tasks:
- name: apache2 package is present
apt:
name: apache2
state: latest
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
Tasks:
---
- name: install and start apache
hosts: web
become: yes
vars:
http_port: 80
tasks:
- name: latest apache2 package is present
apt:
name: apache2
state: latest
- name: latest index.html file is present
copy:
src: files/index.html
dest: /var/www/html/
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