Linux systemd service to prevent a server from going to sleep when there are (active) clients.
Supports SSH and NFS clients. Uses D-Bus inhibit to prevent sleep/suspend.
Note: For full functionality you must run this as root to allow access to /proc/.... in order to determine if SSH sessions are active or idle. Depending on Linux configuration, access to the system D-Bus may also require root. In this case the program must be run as root. Installation instructions are for a service running as root.
Tested on Fedora 39 with NFSv4.
Installation
Install OS package dependencies
sudo dnf install python3-pystemd
Create a python virtual environment and install prevent-sleep
cd /opt
sudo python -m venv prevent_sleep --system-site-packages --upgrade-deps
sudo prevent_sleep/bin/python -m pip install --upgrade prevent-sleep # or use path to sourcedir
prevent_sleep/bin/prevent-sleep --versionSetup systemd service
sudo prevent_sleep/bin/prevent-sleep --install-service
sudo systemctl daemon-reload
sudo systemctl enable --now prevent-sleepVerify
Note: Use systemd-inhibit to check if this or other programs are preventing suspend.
[xxx@yyy opt]$ systemd-inhibit
WHO UID USER PID COMM WHAT WHY MODE
ModemManager 0 root 1197 ModemManager sleep ModemManager needs to reset devices delay
NetworkManager 0 root 1239 NetworkManager sleep NetworkManager needs to turn off networks delay
UPower 0 root 1794 upowerd sleep Pause device polling delay
prevent-sleep 0 root 4678 prevent-sleep sleep SSH: 2 active clients [(3567, 'john'), (4007, 'jane')] block
gdm 42 gdm 1846 gsd-power handle-lid-switch External monitor attached or configuration changed recently block
gdm 42 gdm 1846 gsd-power sleep GNOME needs to lock the screen delay
6 inhibitors listed.
[xxx@yyy opt]$ systemd-inhibit
WHO UID USER PID COMM WHAT WHY MODE
ModemManager 0 root 1197 ModemManager sleep ModemManager needs to reset devices delay
NetworkManager 0 root 1239 NetworkManager sleep NetworkManager needs to turn off networks delay
UPower 0 root 1794 upowerd sleep Pause device polling delay
prevent-sleep 0 root 4678 prevent-sleep sleep NFS: 1 clients [('4', '192.168.4.107, Linux NFSv4.2 mylaptop')] block
prevent-sleep 0 root 4678 prevent-sleep sleep SSH: No activity. Will remove block at 2024-01-28T19:36:51 block
gdm 42 gdm 1846 gsd-power handle-lid-switch External monitor attached or configuration changed recently block
gdm 42 gdm 1846 gsd-power sleep GNOME needs to lock the screen delay
7 inhibitors listed.
Note that only SSH clients with traffic during the last check period will prevent sleep!
Development
sudo dnf install systemd-devel python3{.10,.11,.12}-devel # For all python versions listen in noxfile.py
pip install nox
nox # In root of checked out sourcesNote that the test is rather rudimentary. It is not mocked (yet) so running it will require D-Bus access and it will fail if being run on a server with NFS clients (if not run as root).
More
This program [https://pypi.org/project/sleep-inhibitor/], which I found after writing prevent-sleep, does a similar thing.
