Jenkins-4

                                                            Jenkins Slave Setup-1

As we all know jenkins is CI/CD tool it is used to schedule jobs.We can schedule multiple jobs using jenkins. These makes a little bit burden on Jenkins master.To reduce that burden we use slave nodes.These slave nodes takes the burden of some jobs from master.

One master can have any number of slaves.

à In my enviornment i am using 3 vms
1.server1.abc.com
2.server2.abc.com
3.server3.abc.com

à The server1.abc.com i am using as jenkins master and server2.abc.com i want to make slave for the server1.abc.com.

To make a slave i don't need to install jenkins on server2.abc.com.

à In this case i installed jenkins on server1.abc.com only.when you install jenkins it creates a user with jenkins on server1. You can't login using that jenkins user.to login with that user we do following things.

Go to 


[root@server1 ~]# vi /etc/passwd

jenkins:x:500:500:jenkins:/home/jenkins:/bin/false

change that false as bash

jenkins:x:500:500:jenkins:/home/jenkins:/bin/bash

à Then give sudo permissions to the jenkins user using visudo command as follws

[root@server1 ~]# visudo

## Allow root to run any commands anywhere

root    ALL=(ALL)          ALL

test    ALL=(ALL) NOPASSWD:ALL

dhoni   ALL=(ALL) NOPASSWD:ALL

jenkins ALL=(ALL) NOPASSWD:ALL

Esc+Shift+wq+:    Save it

à Then goto server2.abc.com create a user with the a name of jenkins and give sudo permissions to him.as below

[root@server2 ~]# useradd jenkins

[root@server2 ~]# passwd jenkins

Changing password for user jenkins.

New password:

BAD PASSWORD: it is based on a dictionary word

BAD PASSWORD: is too simple

Retype new password:

passwd: all authentication tokens updated successfully.

à

[root@server1 ~]# visudo

## Allow root to run any commands anywhere

root    ALL=(ALL)          ALL

jenkins ALL=(ALL) NOPASSWD:ALL

Esc+Shift+wq+:    Save it

à Now login on server1.abc.com as jenkins by simply below command switch user(su)

[root@server1 ~]# su jenkins

bash-4.1$ ssh-keygen

                                                          Then Press Enter you will get the below text

Generating public/private rsa key pair.

Enter file in which to save the key (/var/lib/jenkins/.ssh/id_rsa):

Created directory '/var/lib/jenkins/.ssh'.

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in /var/lib/jenkins/.ssh/id_rsa.

Your public key has been saved in /var/lib/jenkins/.ssh/id_rsa.pub.

The key fingerprint is:

47:39:ed:50:b5:ab:1c:08:24:a8:5a:da:83:5e:dd:89 jenkins@server1.abc.com

The key's randomart image is:

+--[ RSA 2048]----+

|     .. .   ...  |

|    .  o   +   . |

|   .    . = . .  |

|  o      o =   . |

| *  . o S o o .  |

|+ o. E o . . o   |

|. ..        o    |

| .               |

|                 |

+-----------------+

à

 Then copy that key to server2.abc.com

bash-4.1$ ssh-copy-id server2.abc.com

The authenticity of host 'server2.abc.com (192.168.33.11)' can't be established.

RSA key fingerprint is 90:d8:41:6f:c5:39:1d:54:0d:43:4e:34:dc:f1:d2:6b.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added 'server2.abc.com,192.168.33.11' (RSA) to the list of known hosts.

jenkins@server2.abc.com's password:

Now try logging into the machine, with "ssh 'server2.abc.com'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

à

  Check it wheather its working or not by below command.

bash-4.1$ ssh server2.abc.com

[jenkins@server2 ~]$ exit

logout

Connection to server2.abc.com closed.

à

 To exit from the bash script.

bash-4.1$ exit

exit

[root@server1 ~]#

If you face any problem while practicing feel free to comment it and Bookmark this blog for quick reference.We will try to help you

Thanks
Devops Desk Team