HowToLinuxBlog

Ansible is a radically simple IT automation system. It handles configuration-management, application deployment, cloud provisioning, ad-hoc task-
execution, and multinode orchestration – including trivializing things like zero downtime rolling updates with load balancers.

Step 1: Install Ansible

On Debian based systems:

apt-get insatll ansible -y

On RPM Based systems

yum install ansible -y

Ansible config files:

# ls -l /etc/ansible/
total 16
-rw-r--r-- 1 root root 10301 Jan 14 2017 ansible.cfg
-rw-r--r-- 1 root root 995 Jan 17 01:59 hosts

Ansiable works on password less ssh, No client side configuration required, you only have to setup password less ssh from server to clients. Follow below steps to setup password less access.

Step 2: On Ansible server generate ssh key

Run ssh-keygen command to create new ssh key hit enter for default file location do not add passphrase when asked leave it blank and hit enter.

[root@server]# ssh-keygen -t rsa
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:
df:24:ac:c5:7d:5f:0c:ca:8d:17:c2:92:25:3a:80:45 root@server
The key's randomart image is:
+--[ RSA 2048]----+
| E |
| . |
| . . |
| o = o = o |
|. . . S B A + o|
| . . . * = o ..|
| o . . . .|
| . |
| |
+-----------------+

.ssh directory get created inside roots home directory

# ls ~/.ssh/ 
id_rsa id_rsa.pub

Step 3 : Copy ssh key on Ansible clients

Copy id_rsa.pub key on clients.

# scp ~/.ssh/id_rsa.pub root@client:~/.ssh/authorized_keys

Ansible is now ready to do its magic.

“/etc/ansible/hosts” is default ansible ‘hosts’ file. Edit it and add ipaddress of your clients at the file or you can create host groups

# Ex 1: Ungrouped hosts, specify before any group headers.

green.example.com
blue.example.com
192.168.100.1
192.168.100.10

# Ex 2: A collection of hosts belonging to the ‘webservers’ group

[webservers]
alpha.example.org
beta.example.org
192.168.1.100
192.168.1.110

On this example we have this:

cat /etc/ansible/hosts|tail -n3
10.192.80.31
[webservers]
10.192.80.31

Step 4 : Run ansible

~# ansible -m ping 10.192.80.31
10.192.80.31 | SUCCESS => {
 "changed": false,
 "ping": "pong"
}

For individual client:

root@puppet:~# ansible -m shell -a "ps -ef|grep named" 10.192.8.31
10.192.8.31 | SUCCESS | rc=0 >>
root 1481 1 0 Jun17 ? 00:00:00 /usr/local/sbin/named -c /etc/named.conf
root 5774 5773 0 03:21 pts/2 00:00:00 /bin/sh -c ps -ef|grep named

For webservers group:

root@puppet:~# ansible -m shell -a "ps -ef|grep httpd" webservers
10.192.8.31 | SUCCESS | rc=0 >>
root 1379 1 0 Jun17 ? 00:00:01 /usr/sbin/httpd
git 5616 1379 0 03:17 ? 00:00:00 /usr/sbin/httpd
git 5617 1379 0 03:17 ? 00:00:00 /usr/sbin/httpd