ovsdb-server.service Warning and Network Timeout After Upgrade

Problem Statement

After updating Ubuntu systems with apt upgrade and rebooting, many users encounter two related issues:

1. OVSDB Service Warning:
   When applying network configurations with sudo netplan apply, the system outputs:

   WARNING:root:Cannot call Open vSwitch: ovsdb-server.service is not running.

   This occurs despite Open vSwitch (OVS) never being installed.

2. Network Configuration Timeout:
   The systemd-networkd-wait-online.service fails with a timeout:

   × systemd-networkd-wait-online.service - Wait for Network to be Configured
     Active: failed (Result: timeout)

   This happens even though Ethernet/Wi-Fi interfaces obtain valid IP addresses.

These issues are caused by:

• A known bug in netplan that incorrectly checks for OVS
• Overly broad network interface waiting logic in systemd
• Specific package interactions in recent Ubuntu updates

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Solutions

1. Resolving OVSB Server Warning

Recommended Method: Install Open vSwitch

sudo apt update
sudo apt install openvswitch-switch
sudo netplan apply  # Verify warning disappears

For Raspberry Pi Systems:

sudo apt install linux-modules-extra-raspi
sudo apt install openvswitch-switch
sudo netplan try

If you prefer not to install OVS, ignore the harmless warning (bug fix pending).

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2. Fixing Network Timeout Failure

Modify the wait service to target only essential interfaces:

Step 1: Find Active Interfaces

ip a

Identify critical interfaces (e.g., eth0, wlan0)

Step 2: Create Service Override

sudo mkdir -p /etc/systemd/system/systemd-networkd-wait-online.service.d
sudo nano /etc/systemd/system/systemd-networkd-wait-online.service.d/override.conf

Add this configuration (adapt interfaces as needed):

[Service]
ExecStart=
ExecStart=/lib/systemd/systemd-networkd-wait-online --interface=eth0 --interface=wlan0
TimeoutStartSec=30sec

Step 3: Apply Changes

sudo systemctl daemon-reload
sudo systemctl restart systemd-networkd-wait-online.service
sudo systemctl status systemd-networkd-wait-online.service  # Verify active status

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Alternative Network Wait Approach

To skip waiting entirely (not recommended for servers):

sudo systemctl mask systemd-networkd-wait-online.service

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Explanation

Why Does This Happen?

1. OVS Warning Bug
   Recent netplan updates contain a defect that incorrectly checks for OVS database services, triggering false warnings.

2. Network Timeout Causes
   The default systemd-networkd-wait-online.service waits for all interfaces, including:

   • Dormant virtual interfaces
   • Disconnected ports
   • Non-essential devices
     This causes unnecessary timeouts.

Best Practice Recommendations

1. Prefer Targeted Interface Waiting
   Constraining --interface to essential connections aligns with the Ubuntu 22.04+ recommendation for headless servers.

2. Adjust Timeouts Conservatively
   30sec works for most systems - increase only if using complex network topologies.

3. Monitor Bug Fixes
   Track Launchpad Bug #2041727 for native resolution of OVS warnings.

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Verification

Confirm both issues are resolved with:

sudo netplan apply  # Should show no warnings
systemctl status systemd-networkd-wait-online.service  # Should show active

Important: After fixing, reboot once to confirm persistence:

sudo reboot