Nexus_Install_Nginx_Proxy

To install Nexus Repository Manager on Ubuntu 24.04 with Nginx configured as a reverse proxy, follow these steps:

These steps can also work on Ubuntu 16.04, 18, 20, 22, 24.04 (2GB Ram, 1 CPU capacity server) 
And off-course on RHEL Family too. 

Minimum Hardware Requirements:
CPU: 2 CPU cores
RAM: 2/4 GB of RAM
Disk Space: 8-10 GB

*Pre-requisites*
	Java/JDK 

Security groups/Port numbers
-	8081
-	80  

Step 1: Install Java (OpenJDK)
Nexus requires Java to run. Install OpenJDK:
$ sudo apt update
$ sudo apt install openjdk-11-jdk -y

Verify Java installation:
$ java -version

Step 2: Create a Nexus User
Create a user for Nexus:
$ sudo adduser nexus
$ sudo passwd nexus
$ sudo usermod -aG sudo nexus

Step 3: Download and Install Nexus
Download the latest Nexus version:   
wget https://download.sonatype.com/nexus/3/latest-unix.tar.gz
Extract the archive:
$ tar -xvzf latest-unix.tar.gz

Move the files to /opt/:
$ sudo mv nexus-3.* /opt/nexus
$ sudo mv sonatype-work /opt/sonatype-work


Step 4: Set Permissions
Assign the correct permissions:
$ sudo chown -R nexus:nexus /opt/nexus
$ sudo chown -R nexus:nexus /opt/sonatype-work

Step 5: Configure Nexus
Edit the Nexus configuration file to specify the Nexus user:
$ sudo vi /opt/nexus/bin/nexus.rc

Add this line:
run_as_user="nexus"

Step 6: Create a Systemd Service for Nexus
Create a service file for Nexus:
$ sudo vi /etc/systemd/system/nexus.service

Add the following content:
[Unit]
Description=Nexus Repository Manager 
After=network.target

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

[Install]
WantedBy=multi-user.target

Enable and start Nexus:  
$ sudo systemctl enable nexus
$ sudo systemctl start nexus

Verify the service is running:   
$ sudo systemctl status nexus

Step 7: Install Nginx
Install Nginx, which will serve as the reverse proxy for Nexus:
$ sudo apt install nginx -y

Step 8: Configure Nginx as a Reverse Proxy
Edit the Nginx configuration file:

$ sudo vi /etc/nginx/sites-available/nexus

Add the following content, assuming Nexus is running on localhost and Nginx will proxy traffic on port 8081:
   
server {
    listen 80;
    server_name nexus.example.com;  # Change to your domain or IP

    location / {
        proxy_pass http://localhost:8081;
        proxy_set_header   Host $host;
        proxy_set_header   X-Real-IP $remote_addr;
        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header   X-Forwarded-Proto $scheme;
        proxy_buffering off;
    }
}

Create a symbolic link to enable the configuration:

$ sudo ln -s /etc/nginx/sites-available/nexus /etc/nginx/sites-enabled/

Test the Nginx configuration:
$ sudo nginx -t

Reload Nginx:
 	$ sudo systemctl reload nginx


Step 9: Open Nexus in Browser
Nexus is now accessible at:
http://nexus.example.com
Replace nexus.example.com with your domain or server's public IP address.

Step 10: Initial Nexus Login
The default admin credentials for Nexus:
•	Username: admin
•	Password: Found in the file /opt/sonatype-work/nexus3/admin.password.
Retrieve the password:
     
$ cat /opt/sonatype-work/nexus3/admin.password
You can now log in and start using Nexus through the Nginx reverse proxy.