1. Download Debian 12 Server from here: debian.org/distrib and install your machine.
2. Install Java 17:

   sudo apt install openjdk-17-jdk

3. Add user nexus to run Nexus3:

   adduser nexus

4. Download the latest Nexus3 from https://help.sonatype.com/en/download.html
5. Unpack it to /opt/:

   tar xzvf <downloaded-tar-package>.tar.gz -C /opt

6. Change owner of unpacked files:

   chown nexus -R /opt/nexus-<version>

7. Make binary executeable:

   chmod +x /opt/nexus-<version>/bin/nexus

8. Create systemservice with the name nexus.service and copy it to /etc/systemd/system (keep in mind to add the nexus version):

   nexus.service

   [Unit]
   Description=nexus service
   After=network.target
    
   [Service]
   Type=forking
   Environment="NEXUS_SECRETS_KEY_FILE=/opt/sonatype-work/nexus3/keystores/nexus.secrets.json"
   LimitNPROC=65536
   LimitNOFILE=65536
   ExecStart=/opt/nexus-<version>/bin/nexus start
   ExecStop=/opt/nexus-<version>/bin/nexus stop 
   User=nexus
   Restart=on-abort
   TimeoutSec=600
    
   [Install]
   WantedBy=multi-user.target

   cp nexus.service /etc/systemd/system

   systemctl start nexus.service

   systemctl enable nexus.service

9. When everything was successful, enter the webservice with http://<ip>:8081/
10. The password for admin is located under /opt/sonatype/sonatype-work/nexus3/admin.password after entering the password, it's forced to be changed.

    cat /opt/sonatype/sonatype-work/nexus3/admin.password

    The installation of Nexus is now finished!

1. Firstly create a GPG-Key for signing the release file:
2. Therefore install gpg and generate a key with

   gpg --gen-key

   . Then export the key with to paste it under APT Settings:

   gpg --export-secret-key --armor <KEY-ID> > Key.gpg

3. If your key is password-secured enter the passphrase in the field below.
4. Then add the name above e.g. apt, and set the distribution e.g. to stable
5. It's then recommended to upload the public-release-key to a RAW storage to make it easy to download. Therefore export the public key with:

   gpg --armor --export <KEY-ID> > Key.gpg

6. Finally add the repo to APT:

   echo "deb [signed-by=/usr/share/keyrings/your-repo.gpg] https://<your-repo>/repository/apt/ stable main" | sudo tee /etc/apt/sources.list.d/<your-repo>.list

7. And add the key:

   curl -sS https://<your-repo>/repository/storage/ReleaseKey.gpg | gpg --dearmor | sudo tee /usr/share/keyrings/<your-repo>.gpg > /dev/null

8. Finished!

Sourced from:

• github.com/sonatype-nexus-community
• howtoforge.com - install Nexus3 on Ubuntu22
• stackoverflow.com - Nexus serve up chocolatey