Install SonaType Nexus 3 on Ubuntu 16.0.4 | How to configure SonaType Nexus 3 on Ubuntu | Install Nexus 3 on Ubuntu

How to setup SonaType Nexus3 on Ubuntu:

SonaType Nexus3 is one of the popular binary repository managers, used for storing build artifacts such as Jars,WARs, EARs. SonaType Nexus3 is java based application. 

Java
sudo apt-get update

Java 8 installation
sudo apt install openjdk-8-jre-headless -y

Note: Nexus is not compatible with Java 11 in Ubuntu 18.0.4. So we need to install Java 8.

Execute the below commands -  navigate to /opt directory by changing directory:
cd /opt

Download Nexus

sudo wget http://download.sonatype.com/nexus/3/nexus-3.26.1-02-unix.tar.gz

Extract Nexus
sudo tar -xvf nexus-3.26.1-02-unix.tar.gz
sudo mv nexus-3.26.1-02 nexus

Create a user called Nexus
sudo adduser nexus

give some password may be as admin, but do remember.

Keep entering enter for all other values and press y to confirm the entries.

Give permission to Nexus user  
sudo chown -R nexus:nexus /opt/nexus
sudo chown -R nexus:nexus /opt/sonatype-work

sudo vi /opt/nexus/bin/nexus.rc

change run_as_user="nexus"

Modify memory settings
sudo vi /opt/nexus/bin/nexus.vmoptions

Add all the below changes the file with below yellow highlighted entry:

Configure Nexus to run as a service
sudo vi /etc/systemd/system/nexus.service
Copy the below content highlighted in green color.

[Unit]
Description=nexus service
After=network.target

[Service]
Type=forking
LimitNOFILE=65536
User=nexus
Group=nexus
ExecStart=/opt/nexus/bin/nexus start
ExecStop=/opt/nexus/bin/nexus stop
User=nexus
Restart=on-abort

[Install]
WantedBy=multi-user.target

Now Start Nexus

sudo systemctl enable nexus

sudo systemctl start nexus 

sudo systemctl status nexus 

If it says stopped, review the steps above and you can troubleshoot by looking into Nexus logs by executing below command:

tail -f /opt/sonatype-work/nexus3/log/nexus.log

It should say Nexus is running..If you see Nexus stopped message, review the steps above.

Press control C to come out of the above window. 

Once Nexus is successfully installed, you can access it in the browser by 

 URL - http://public_dns_name:8081

Now click on Sign in, enter admin as user name and password by executing below cat command.

cat /opt/sonatype-work/nexus3/admin.password
Now change admin password as admin123



Now click next, do not check Enable anonymous access.

Click Finish.

Now login with user name/password is admin/admin123

Please follow steps for integrating Nexus with Jenkins

http://www.cidevops.com/2018/06/jenkins-nexus-integration-how-to.html