Ansible Fundamentals

Stefano Morandi

2017-03-04

Created: 2020-09-16 Wed 12:07

Intro

  • SCM overview
  • Ansible overview
  • Ansible components
    • Modules / Playbooks / Roles
  • Live code session

Software Configuration Management

Server Configuration Management

IT automation tools

SCM is a solution for turning your infrastructure administration into a codebase

e.heidi

competitors

  • Puppet
  • Chef
  • Salt
  • 10.000 lines of handmade bash script
  • Ansible

SCM benefits

quick provisioning

very fast setup, very fast restore :-D

self-documented procedures

all tasks are described in text files

easy versioning

versioning text file is quite easy

time saving / cost reduction

setup and configure production servers in minutes

Idempotence

Idempotence is the property of certain operations in mathematics and computer science, that can be applied multiple times without changing the result beyond the initial application

wikipedia

\(f(f(x)) = f(x)\)

* ansible_logo.png

Ansible is..

Ansible is an automation and configuration management technology used to provision, deploy, and manage compute infrastructure across cloud, virtual, and physical environments.

RedHat

Features

Simple

Everythings is in a simple and human readable YAML files

Powerful

More than 750 modules!

No Magic

All tasks are executed in order

Agentless

Only SSH and python

Ansible is…

automation

Core components

ansible engine

inventory

list of hosts and/or network devices with name, ip address and other variables; can be organized in groups

default /etc/ansible/hosts

Inventory

[web]
10.0.0.100
nginx01.lab.pnlug.lan ansible_host=10.0.2.22

[app]
apache[01:99] http_port=8080

[sql]
pg[01:99]

[all:vars]
ansible_user=root

modules

bit of code executed on remote machines

written in many languages (python, bash, powershell…)

returns json 

ansible -i hosts all -m ping
ansible -i hosts db01 -m command -a "uptime"

modules

playbooks

playbooks are ansible's configuration language

each playbook is composed of one or more plays in a list

each play is composed of tasks

each task invokes ansible modules

** playbooks.png

Playbooks

- name: update/upgrade packages
  apt:
    update_cache: yes
    upgrade: safe
  tags:
    - update

- name: remove puppet packages
  apt:
    update_cache: no
    name: "{{ item }}"
    state: absent
  with_items:
    - puppet
    - puppet-common

roles

role is a set of playbooks, templates, files or variables to achieve a specific goal

** 

% tree roles
roles
└── mongodb
    ├── defaults
    │   └── main.yml
    ├── files
    ├── handlers
    │   └── main.yml
    ├── meta
    │   └── main.yml
    ├── tasks
    │   └── main.yml
    ├── templates
    └── vars
	└── main.yml

Installing

System Requirements

controller

  • python 2.7 (python 3.x tech preview from ansible 2.2)
  • ssh client
  • unix like OS

remote host

  • ssh
  • python

Installing ansible

# Debian / Ubuntu
apt-get install software-properties-common
apt-add-repository ppa:ansible/ansible
# debian
# sed -i "s/jessie/trusty/g" /etc/apt/sources.list.d/ansible-ansible-jessie.list
apt-get update
apt-get install ansible

Installing ansible

# Debian
echo "deb http://ppa.launchpad.net/ansible/ansible/ubuntu trusty main" >> /etc/apt/sources.list.d/ansible.list
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 93C4A3FD7BB9C367
apt-get update
apt-get install ansible

# macOS
brew install ansible

# All :-D
mkvirtualenv -p /usr/bin/python2  ansible
pip install ansible

configuration file

[defaults]
remote_user = root
inventory = hosts.txt
private_key_file = is_rsa_pnlug_ansible
  • /etc/ansible/ansible.cfg
  • $HOME/ansible.cfg
  • `pwd`/ansible.cfg

variables

  • inventory file
  • ansible.cfg
  • roles
  • playbooks
  • command line

16 different places

Examples

ping

$ ansible all -m ping
pnlug-mysql01 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
pnlug-web02 | FAILED! => {
    "changed": false,
    "failed": true,
    "module_stderr": "Shared connection to pnlug-web02 closed.\r\n",
    "module_stdout": "/bin/sh: 1: /usr/bin/python: not found\r\n",
    "msg": "MODULE FAILURE"
}
pnlug-web01 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

raw

$ ansible -m raw -a "apt-get update" pnlug-web02
$ ansible -m raw -a "apt-get install -y python" pnlug-web02

$ ansible all -m ping
pnlug-mysql01 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
pnlug-web01 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
pnlug-web02 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

apt

$ ansible pnlug-web01 -m apt -a "name=mc state=present"
pnlug-web01 | SUCCESS => {
    "cache_update_time": 1488561752,
    "cache_updated": false,
==> "changed": true,
    "stderr": "",
    "stdout": "Reading package lists
...
}

$ ansible pnlug-web01 -m apt -a "name=mc state=present"
pnlug-web01 | SUCCESS => {
    "cache_update_time": 1481102874,
    "cache_updated": false,
==> "changed": false
}

apt

$ ansible pnlug-web02 -m apt -a "name=mc state=absent"
pnlug-web02 | SUCCESS => {
    "changed": true,
    "stderr": "",
    "stdout": "Reading package lists...",
...
    "update-alternatives: using /usr/bin/vim.tiny to provide /usr/bin/view (view) in auto mode",
    "Processing triggers for mime-support (3.59ubuntu1) ..."
 ]
}

$ ansible pnlug-web02 -m apt -a "name=mc state=absent"
pnlug-web02 | SUCCESS => {
    "changed": false
}

information gathering

$ ansible pnlug-web02 -m setup
pnlug-web02 | SUCCESS => {
    "ansible_facts": {
	"ansible_all_ipv4_addresses": [
	    "192.168.25.105"
	],
	"ansible_all_ipv6_addresses": [
	    "fe80::746a:d8ff:fec7:e576"
	],
	"ansible_architecture": "x86_64",
	"ansible_bios_date": "11/09/2013",
	"ansible_bios_version": "J06",
...
    "ansible_os_family": "Debian",
...
     "ansible_virtualization_role": "guest",
     "ansible_virtualization_type": "lxc",
...
}

live session