GitLab and Jenkins configuration through SSH

In my previous post I have mentioned how to integrate GitLab with Jenkins using username and password. Now we will learn how to configure Jenkins and GitLab using SSH connection.

• Login as Jenkins user

sudo su - jenkins

• Run the following command to generate SSH key, 

ssh-keygen

• Now it will create  a directory named .ssh if it doesn't exist, Press enter and re-enter when you are prompted to enter passphrase.

thuvvareka:~ jenkins$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/Shared/Jenkins/.ssh/id_rsa): 
Created directory '/Users/Shared/Jenkins/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /Users/Shared/Jenkins/.ssh/id_rsa.
Your public key has been saved in /Users/Shared/Jenkins/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:O9APiAETUYC87e9T6k18SPFQxEN4R2gJbKG6JLOID64 jenkins@thuvvareka.local
The key's randomart image is:
+---[RSA 2048]----+
|..*=. .oB++.     |
|.. o  .+.B .     |
|  o ...oo o      |
| . ..o o+        |
| o.o. o.S.       |
|o =.. oo.+       |
|+. .. o+o..      |
|.o   +o ..       |
|E.. oo..         |
+----[SHA256]-----+

• You can view a key pair in directory .ssh

thuvvareka:.ssh jenkins$ ls -la
total 16
drwx------   4 jenkins  jenkins   128 Apr 10 15:00 .
drwxr-xr-x  10 jenkins  jenkins   320 Apr 10 15:00 ..
-rw-------   1 jenkins  jenkins  1831 Apr 10 15:00 id_rsa
-rw-r--r--   1 jenkins  jenkins   406 Apr 10 15:00 id_rsa.pub

• Copy id_rsa.pub content in GitLab SSH keys

• Copy id_rsa content in Jenkins credentials

Jenkins -> Credentials -> System -> Global Credentials -> Add Credentials

Now your SSH connection between GitLab and Jenkins has been successfully established.