Ansible

Ansible is an open source automation engine that automates software provisioning, configuration management, and application deployment.

DEPLOY APPS. MANAGE SYSTEMS. CRUSH COMPLEXITY.

Ansible delivers simple IT automation that ends repetitive tasks and frees up DevOps teams for more strategic work.

ANSIBLE OPEN SOURCE 

SIMPLE. POWERFUL. AGENTLESS.

App deployment, configuration management and orchestration - all from one system. Ansible is powerful automation that you can learn quickly.

As with most configuration management software, Ansible has two types of servers: controlling machines and nodes. First, there is a single controlling machine which is where orchestration begins. Nodes are managed by a controlling machine over SSH. The controlling machine describes the location of nodes through its inventory.

To orchestrate nodes, Ansible deploys modules to nodes over SSH. Modules are temporarily stored in the nodes and communicate with the controlling machine through a JSON protocol over the standard output. When Ansible is not managing nodes, it does not consume resources because no daemons or programs are executing for Ansible in the background.

Note :  You can install Ansible upon any linux flavour but here i am using  REDhat 7.1

1)  Installing Ansible  

i)  Method first  :-  Using  RPM  package  or with YUM command

ii)  Method Second :-  Using  python based PIP  installer


Step 1:   First install Pip installer you don't have in your redhat 6.4/7.1

[root@desktop83 ~]# yum  install python-pip

then Install ansible :

[root@desktop83 ~]# pip  install  ansible

After Installation  process this operation  you can check there will be  /etc/ansible directory

OR :

You can use Yum installer if you have repopath setup already.


 For Redhat 6.4 and later
==================

[root@desktop57 ~]# rpm -ivh  http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

[root@desktop57 ~]#  yum   install  ansible

 For Redhat 7.1 and Later

[root@desktop57 ~]# rpm -iUvh http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-5.noarch.rpm

[root@desktop57 ~]#  cd /etc/yum.repos.d

[root@desktop57 yum.repos.d]# cat  live.repo 
[aa]
baseurl=http://mirror.centos.org/centos-7/7.2.1511/os/x86_64/
gpgcheck=0

[bb]
baseurl=http://mirror.centos.org/centos-7/7.2.1511/extras/x86_64/
gpgcheck=0

[root@desktop57 ~]#  yum   install  ansible
root@shalinux:/etc/ansible# cd  /etc/ansible/
root@shalinux:/etc/ansible# ls


hosts

Step 2:  Managing  Servers

Ansible was designed to managed multiple servers from a single system by using SSH 

Important :

Here We have  three  machine  one is Ansible  installed  and other two are the targets where we want to perform operation

Ansible Installed machine is :   192.168.100.104

Target1 --   192.168.100.9
target2 --   192.168.100.10 

Note:   Setup and  and share ssh-keys  from  Ansible machine to target

i)  Generating  ssh-keys

 [root@hmaster ~]# ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
fe:4c:85:36:03:b8:3a:35:35:ec:70:f0:28:bb:ee:a1 root@hmaster.example.com
The key's randomart image is:
+--[ RSA 2048]----+
|      .          |
|       *         |
|    . + B        |
|     o * o .     |
|    . + S = .    |
|     + o . +     |
|    =   . .      |
|   o o   +       |
|  E.o     o      |
+-----------------+

ii)  share keys to both the targets machine 

[root@hmaster ~]# ssh-copy-id   192.168.100.9
[root@hmaster ~]# ssh-copy-id   192.168.100.10

Configure Inventory

Ansible works against multiple systems in your infrastructure at the same time. It does this by selecting portions of systems listed in Ansible’s inventory, which defaults to being saved in the location /etc/ansible/hosts. You can specify a different inventory file using the -i <path> option on the command line.

The inventory file can be in one of many formats, depending on the inventory plugins you have. For this example, the format for /etc/ansible/hosts is an INI-like (one of Ansible’s defaults) and looks like this:

The headings in brackets are group names, which are used in classifying systems and deciding what systems you are controlling at what times and for what purpose.

Now go to Ansible machine and configure the hosts file

iii)   make a backup of host file

root@shalinux:~# cp  /etc/ansible/hosts    /etc/ansible/hosts.backup

iv)  Now edit this file and specify the targets IPS

Important:   File  /etc/ansible/hosts    also known as inventory file


root@shalinux:~# vim  /etc/ansible/hosts

This will look like this

root@shalinux:~# cat  /etc/ansible/hosts
[testing]
192.168.100.9
192.168.100.10

v)  Running  Some basic commands

sending  icmp packets

a)   Sending  Icmp echo-request
 
root@shalinux:~# ansible    testing   -m  ping
192.168.100.9 | success >> {
    "changed": false,
    "ping": "pong"
}

192.168.100.10 | success >> {
    "changed": false,
    "ping": "pong"
}

Here:

ansible  :-  is the command
testing  :-  name defined in inventory file for calling  all the list server
-m       :-  use for specify the module name
ping     :   This is the name of  module which simply send icmp packets to all the define servers


b)   In case you have many entries in inventory file then want to send icmp packets

root@shalinux:~# vim  /etc/ansible/hosts

root@shalinux:~# cat    /etc/ansible/hosts
[testing]
192.168.100.9
192.168.100.10

[apache]
192.168.100.11

root@shalinux:~# ansible   all -m ping  
192.168.100.10 | success >> {
    "changed": false,
    "ping": "pong"
}

192.168.100.9 | success >> {
    "changed": false,
    "ping": "pong"
}

192.168.100.11 | success >> {
    "changed": false,
    "ping": "pong"
}

Note:  

all  :  for  all inventory file  entries
##########
Modules:

Modules are predefined functions in ansible which are used to perform some specific task :
I am listing some names with examples of modules.

Module LIst:

a)  ping
b)  shell
c)  command
=========
example:  testing  date command

root@shalinux:~# ansible  testing  -m   shell  -a  date
192.168.100.109 | success | rc=0 >>
Thu Feb 18 06:54:36 EST 2016

-------------------------------------------------------

root@shalinux:~# ansible  all  -m   shell  -a  date
192.168.100.109 | success | rc=0 >>
Thu Feb 18 06:54:45 EST 2016

192.168.100.108 | success | rc=0 >>
Thu Feb 18 06:54:53 EST 2016

----------------------------------------

Service  Restart for apache web services 

root@shalinux:~# ansible  all  -m   shell  -a  "service  httpd  restart"
192.168.100.109 | success | rc=0 >>

192.168.100.108 | success | rc=0 >>

Using command modules:

root@shalinux:/etc/ansible# ansible all -m command  -a  "date"
192.168.100.109 | success | rc=0 >>
Fri Feb 19 01:06:51 EST 2016

192.168.100.108 | success | rc=0 >>
Fri Feb 19 01:07:04 EST 2016

Note:  with shell module you need to pass  -a  option  for passing  arguments