Setting Up Cockpit for Multi-Server Management (Linux Mint)

This knowledge base article summarizes the steps taken to get Cockpit running, including specific fixes for errors encountered.

Objective

To install Cockpit on a primary Linux Mint server and connect other Linux Mint servers to manage them from a single web interface.

Prerequisites

Step 1: Install Cockpit on the Primary Server

Run these commands on the computer you want to use as your main controller:

1. Install the software:

   sudo apt update && sudo apt install cockpit -y

2. Enable the service:

   sudo systemctl enable --now cockpit.socket

3. Open the firewall:

   sudo ufw allow 9090

Step 2: Troubleshooting Installation Errors

Issue: apt failed due to a broken "synosnap" (Synology Active Backup) package.

Fix: Use a dummy script to trick the system into removing the broken package.

1. Create the dummy script structure:

   sudo mkdir -p /opt/synosnap/hooks/
   sudo touch /opt/synosnap/hooks/dpkg-post-hook.sh
   sudo chmod +x /opt/synosnap/hooks/dpkg-post-hook.sh

2. Force the install to finish:

   sudo apt -f install

3. Purge the broken package:

   sudo dpkg --purge synosnap

Step 3: Prepare Secondary Servers

Issue: "Unable to contact... port 22" when adding a host.
Cause: Linux Mint does not have the SSH server enabled by default.

Run these commands on every secondary server you want to control:

1. Install and enable SSH:

   sudo apt install openssh-server -y
   sudo systemctl enable --now ssh

2. Allow SSH through firewall:

   sudo ufw allow ssh

3. Install Cockpit packages (for metrics):

   sudo apt install cockpit cockpit-pcp -y

Step 4: Connect Servers in the GUI

1. Access the Web Interface: Open a browser and go to https://<PRIMARY_IP>:9090.
2. Note: Accept the "Not Secure" / SSL warning (Advanced -> Proceed).
3. Log in: Use your Linux username and password.
4. Add Host:
   • Click the dropdown menu in the top-left (or "Overview").
   • Click "Add new host".
   • Enter the IP of the secondary server.
   • Check "Log in automatically" to save credentials.

Step 5: Enabling Metrics & History

Issue: Missing graphs/history.
Fix: The cockpit-dashboard package is deprecated. Use PCP (Performance Co-Pilot) instead.

Run this on all servers to enable history recording:

sudo apt install cockpit-pcp -y
sudo systemctl enable --now pmlogger
sudo systemctl enable --now pmproxy

Known Limitations

• Home Assistant: Cannot be added to Cockpit (unless running as a VM inside Linux).
• "Single Pane" Dashboard: The old grid view of all servers at once has been deprecated.
• Navigation: Use the dropdown menu to switch between servers.