26-jenkins-install-first-pipeline.md

Installing and setting up Jenkins - Simple Pipeline Intro

For this, we are not gonna use Docker, we are gonna go the old way and install it on a VM

Installing Jenkins

Step 1 - Install JDK

sudo apt update
sudo apt install default-jdk

Step 2 - Add the GPG keys

wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add -
sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'

Step 3 - Install the package

sudo apt update
sudo apt install jenkins

Step 4 - Start and enable

sudo systemctl enable jenkins
sudo systemctl start jenkins

Step 5 - Setting up

Visit server-ip:8080

Jenkins generates a random password by default. Get the password:

sudo cat /var/lib/jenkins/secrets/initialAdminPassword

Paste this password into the field

Step 6 - Installing plugins

At this point, you would want to install the plugins you need. To get started I would suggest to just install the suggested plugins

Step 7 - Create the admin user

You know how to fill a form. Create a user. From there it is pretty straight forward

Step 8 - Configuring Nginx reverse proxy

Install Nginx

sudo apt update
sudo apt install nginx

Create /etc/nginx/sites-enabled/jenkins.devops.esc.sh

Change the domain name obviously

server {
    listen 80;
    server_name jenkins.devops.esc.sh;

	location / {
		include /etc/nginx/proxy_params;
		proxy_pass          http://localhost:8080;
		proxy_read_timeout  60s;
        # Fix the "It appears that your reverse proxy set up is broken" error.
        # Make sure the domain name is correct
		proxy_redirect      http://localhost:8080 https://jenkins.devops.esc.sh;
	}
}

Verify the config and restart nginx

nginx -t
sudo systemctl restart nginx

Fix if any syntax error

Step 9 - Change Jenkins bind address

By default Jenkins listens on all network interfaces. But we need to disable it because we are using Nginx as a reverse proxy and there is no reason for Jenkins to be exposed to other network interfaces.

We can change this by editing /etc/default/jenkins

Locate the line starting with JENKINS_ARGS (It's usually the last line) and append

--httpListenAddress=127.0.0.1

So that the line resembles

JENKINS_ARGS="--webroot=/var/cache/$NAME/war --httpPort=$HTTP_PORT --httpListenAddress=127.0.0.1"

Restart Jenkins

sudo systemctl restart jenkins

Make sure it is running fine

sudo systemctl status jenkins

Jenkins should load now, but on http only.

Step 9 - Configuring SSL

There is a dedicated document for fetching and configuring SSL with Nginx with all the necessary documents. Go HERE

Come back here after that.

Make sure you have the certificate and key in location

root@jenkins-server:~# ls -l /etc/letsencrypt/live/jenkins.devops.esc.sh/
total 4
lrwxrwxrwx 1 root root  45 Sep 27 07:52 cert.pem -> ../../archive/jenkins.devops.esc.sh/cert1.pem
lrwxrwxrwx 1 root root  46 Sep 27 07:52 chain.pem -> ../../archive/jenkins.devops.esc.sh/chain1.pem
lrwxrwxrwx 1 root root  50 Sep 27 07:52 fullchain.pem -> ../../archive/jenkins.devops.esc.sh/fullchain1.pem
lrwxrwxrwx 1 root root  48 Sep 27 07:52 privkey.pem -> ../../archive/jenkins.devops.esc.sh/privkey1.pem
-rw-r--r-- 1 root root 692 Sep 27 07:52 README
root@jenkins-server:~#

Update the nginx config to look like this

server {
    listen 80;
    server_name jenkins.devops.esc.sh;

	location / {
        return 301 https://$host$request_uri;
	}
}

server {
    listen 443 ssl;

    server_name jenkins.devops.esc.sh;

    ssl_certificate /etc/letsencrypt/live/jenkins.devops.esc.sh/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/jenkins.devops.esc.sh/privkey.pem;
    include /etc/letsencrypt/options-ssl-nginx.conf;
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;


    
	location / {
		include /etc/nginx/proxy_params;
		proxy_pass          http://localhost:8080;
		proxy_read_timeout  60s;
        # Fix the "It appears that your reverse proxy set up is broken" error.
        # Make sure the domain name is correct
		proxy_redirect      http://localhost:8080 https://jenkins.devops.esc.sh;
	}
}

Make sure nginx is alright nginx -t

Reload Nginx

sudo systemctl reload nginx

And that is pretty much it, Jenkins is up and ready with a freshly configured sweet sweet green padlocked SSL certificate

A Simple multi stage pipeline

You can create a pipeline by New Item -> Pipeline. And then in the pipeline definition

pipeline {
    agent any

    stages {
        stage('build') {
            steps {
                echo 'building the software'
            }
        }
        stage('test') {
            steps {
                echo 'testing the software'
            }
        }
        stage('deploy') {
            steps {
                echo 'deploying the software'
            }
        }
    }
}