This content is out of date. See the Ubuntu installation section of the handbook on jenkins.io for Debian and Ubuntu installation instructions

On Debian-based distributions, such as Ubuntu, you can install Jenkins through apt-get.

Recent versions are available in an apt repository. Older but stable LTS versions are in this apt repository.

You need to have a JDK and JRE installed. openjdk-7-jre and openjdk-7-jdk are suggested. As of 2011-08 gcj is known to be problematic - see https://issues.jenkins-ci.org/browse/JENKINS-743.

Please make sure to back up any current Hudson or Jenkins files you may have.

Installation

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

Upgrade

Once installed like this, you can update to the later version of Jenkins (when it comes out) by running the following commands:

sudo apt-get update
sudo apt-get install jenkins

(aptitude or apt-get doesn't make any difference.)

What does this package do?

Jenkins will be launched as a daemon up on start. See /etc/init.d/jenkins for more details.
The 'jenkins' user is created to run this service.
Log file will be placed in /var/log/jenkins/jenkins.log. Check this file if you are troubleshooting Jenkins.
/etc/default/jenkins will capture configuration parameters for the launch like e.g JENKINS_HOME
By default, Jenkins listen on port 8080. Access this port with your browser to start configuration.

If your /etc/init.d/jenkins file fails to start jenkins, edit the /etc/default/jenkins to replace the line

HTTP_PORT=8080

by

HTTP_PORT=8081

Here, 8081 was chosen but you can put another port available.

Deploying on Ubuntu in a cloud (EC2, HP Cloud, OpenStack)

The Ubuntu Jenkins maintainer also maintains the Juju charm deployment/management script for deployment in clouds. It's designed to make it easy to deploy a master with multiple slaves:

juju deploy jenkins
juju deploy -n 5 jenkins-slave
juju add-relation jenkins jenkins-slave

The default password for the 'admin' account will be auto-generated. You can set it using:

juju set jenkins password=mypassword

Always change it this way - this account is used by the charm to manage slave configuration. Then feel free to expose your jenkins master:

juju expose jenkins

Using Linux iptables for port 80 -> 8080

This enables port forwarding of traffic between ports 80 and 8080. You can keep Jenkins on the default port 8080 and access it with a normal url without installing anything extra.
sudo nano /etc/rc.local
Then add the following just before the exit 0

#Requests from outside
iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 8080
#Requests from localhost
iptables -t nat -I OUTPUT -p tcp -d 127.0.0.1 --dport 80 -j REDIRECT --to-ports 8080

Now reboot or run sudo /etc/rc.local to enable port forwarding. Additional info: https://gist.github.com/m5m1th/6870a54717c0387468c3

Setting up an Apache Proxy for port 80 -> 8080

This configuration will setup Apache2 to proxy port 80 to 8080 so that you can keep Jenkins on 8080.
sudo aptitude install apache2
sudo a2enmod proxy
sudo a2enmod proxy_http

do not do this next command if you already have virtual hosting setup that depends on the default site. See my comment below - danapsimer

sudo a2dissite default

If you get ERROR: Site default does not exist! then try this instead:

sudo a2dissite 000-default

And if all else fails just have a look if there is a default site set up at all:

ls /etc/apache2/sites-enabled/

Create a file called jenkins.conf in /etc/apache2/sites-available

<VirtualHost *:80>
	ServerAdmin webmaster@localhost
	ServerName ci.company.com
	ServerAlias ci
	ProxyRequests Off
	<Proxy *>
		Order deny,allow
		Allow from all
	</Proxy>
	ProxyPreserveHost on
	ProxyPass / http://localhost:8080/ nocanon
	AllowEncodedSlashes NoDecode
</VirtualHost>

sudo a2ensite jenkins
sudo apache2ctl restart

Setting up an Nginx Proxy for port 80 -> 8080

This configuration will setup Nginx to proxy port 80 to 8080 so that you can keep Jenkins on 8080. Instructions originally found in a GitHub Gist from rdegges: https://gist.github.com/913102

Install Nginx.
sudo aptitude -y install nginx

Remove default configuration.

cd /etc/nginx/sites-available
sudo rm default ../sites-enabled/default

Create new configuration for Jenkins. This example uses cat, but you can use your favorite text editor. Make sure to replace 'ci.yourcompany.com' with your domain name.
Note: Sometimes your permissions (umask, etc) might be setup such that this won't work. Create the file somewhere else then copy it into place if you run into that problem.

sudo cat > jenkins
upstream app_server {
    server 127.0.0.1:8080 fail_timeout=0;
}

server {
    listen 80;
    listen [::]:80 default ipv6only=on;
    server_name ci.yourcompany.com;

    location / {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;

        if (!-f $request_filename) {
            proxy_pass http://app_server;
            break;
        }
    }
}
^D # Hit CTRL + D to finish writing the file

Link your configuration from sites-available to sites-enabled:

sudo ln -s /etc/nginx/sites-available/jenkins /etc/nginx/sites-enabled/

Restart Nginx
sudo service nginx restart

Where to go from here?

You might want to make Jenkins visible through Apache, to make it available on port 80 (for example, http://myserver/jenkins/ instead of http://myserver:8080/). See this blog for more details
You might want to see latest releases of Jenkins Debian packages. See http://pkg.jenkins-ci.org/debian-stable/