Setting up Jenkins on Ubuntu dedicated server

As a developer, often you are blocked by repetitive tasks that need be done. This is something that can become frustrating, but luckly we have some tools to help. In the following lines we will talk about Jenkins, an automation server written in Java.

Assumptions

Your Ubuntu has a public IP address
Your sudo username is: admin
Your host is: jenkins.example.com
You have a cname DNS entry for every subdomain of jenkins.example.com pointing to itself.

The setup

Please note that there are commands which are not mandatory and everything can be adapted to the needs of your system (e.g. You might choose not to use nginx)

Sudo user

sudo apt-get update
adduser admin
usermod -aG sudo admin
sudo passwd -l root
su - admin

The locale

locale
sudo apt-get install language-pack-en-base
sudo dpkg-reconfigure locales

Swap

If using digitalocean, swap is not recommended.

sudo swapon --show
sudo fallocate -l 4G /swapfile
ls -lh /swapfile
sudo chmod 600 /swapfile
ls -lh /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile
sudo swapon --show

Make swap permanent

sudo nano /etc/fstab
and add at the end:
/swapfile none swap sw 0 0

Firewall

sudo ufw allow 8080
sudo ufw allow OpenSSH
sudo ufw enable

Setup java

sudo apt-get install default-jre

Jenkins

sudo apt-get install jenkins
sudo systemctl start jenkins
sudo systemctl status jenkins
sudo nano /var/lib/jenkins/secrets/initialAdminPassword
Access `http://jenkins.example.com:8080/` to finish setup.

"Package 'jenkins' has no installation candidate"

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

"ubuntu 18.04 jenkins found an incorrect java version"

sudo add-apt-repository ppa:webupd8team/java
sudo apt install oracle-java8-installer
wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add -
sudo apt-add-repository "deb https://pkg.jenkins.io/debian-stable binary/"
sudo apt install jenkins

nginx

sudo apt-get update
sudo apt-get install nginx
sudo ufw allow 'Nginx HTTP'
sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update
sudo apt-get install python-certbot-nginx
sudo nano /etc/nginx/sites-available/default
- replace `server_name _` with server_name jenkins.example.com www.jenkins.example.com;
sudo nginx -t
sudo systemctl reload nginx

sudo ufw allow 'Nginx Full'
sudo ufw delete allow 'Nginx HTTP'
sudo certbot --nginx -d jenkins.example.com -d www.jenkins.example.com
Choose redirect all traffic to https://

Use Jenkins with ssl nginx

sudo nano /etc/nginx/sites-available/default

find try_files $uri $uri/ =404;

replace with:

# try_files $uri $uri/ =404;
include /etc/nginx/proxy_params;
proxy_pass          http://localhost:8080;
proxy_read_timeout  90s;
# Fix potential "It appears that your reverse proxy set up is broken" error.
proxy_redirect      http://localhost:8080 https://jenkins.example.com;

sudo nano /etc/default/jenkins
- find
  JENKINS_ARGS="--webroot=/var/cache/$NAME/war --httpPort=$HTTP_PORT"
- replace with:
  JENKINS_ARGS="--webroot=/var/cache/$NAME/war --httpPort=$HTTP_PORT --httpListenAddress=127.0.0.1"
sudo systemctl restart jenkins
sudo systemctl restart nginx
Go to: https://jenkins.example.com and choose: Manage jenkins > Configure system and update Jenkins location > Jenkins URL to https://jenkins.example.com.

Blueocean

For a better UI/UX experience, you could install the BlueOcean plugin, from the jenkins available plugins.

Docker

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
sudo apt-get update
apt-cache policy docker-ce
sudo apt-get install -y docker-ce