Water Cooler Monitor

Water Cooler Monitor is a simple linux service to send temperature information in C⁰ to your water cooler display. Its build to fix the absence of software support for linux systems.

This tutorial was tested in Fedora distribution.

• How to use: Using wcoolmon -h command line will print the help below with many command options.

❯ wcoolmon -h
Usage: wcoolmon [OPTIONS]

Options:
  -v, --vendor-id <VENDOR_ID>    HID device vendor Id [default: 43656]
  -p, --product-id <PRODUCT_ID>  HID device product Id [default: 34406]
  -i, --interval <INTERVAL>      Time interval to update temperature info [default: 1000]
  -r, --verbose                  Verbose. Prints temperature info in C⁰ to stdout
  -h, --help                     Print help
  -V, --version                  Print version

• You need to list your HID Devices using lsusb and indentify your cooler pid(product_id) and vid(vendor_id).

❯ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID aa88:8666 东莞铭研电子科技 温度显示HID设备 **
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 002: ID 0403:6001 Future Technology Devices International, Ltd FT232 Serial (UART) IC
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 004 Device 002: ID 0bda:b82c Realtek Semiconductor Corp. 802.11ac NIC

After run wcoolmon with the necessary options options above and fill your vendor id and product id water cooler hardware:

❯ sudo wcoolmon -v<vendor_id> -p<product_id>

• Installation: First of all, you need to clone this repository and compile wcoolmon. Its a Rust application static contained, thats it, you dont need to care with dependencies at runtime (only in compile time).

So, using gh github commandline, or git, just clone the repository:

❯ gh repo clone jgardona/wcoolmon

Build the release profile version of this service. Its configured to be high optimized at level z, and remove unecessary strings from the executable to save size. Once in wcoolmon root folder:

❯ cargo build --release

1- Installing the service:

• Monitor permissions: Its necessary to give the linux system permissions to access the device we found above. For that, we need to create a rule in the folder rules.d, as we can see below.

sudo nano /etc/udev/rules.d/99-wcoolmon.rules

We have to write the following content to the file

SUBSYSTEM=="hidraw", ATTRS{idVendor}=="<Seu_IDVendor>", ATTRS{idProduct}=="<Seu_IDProduct>", MODE="0666", TAG+="uaccess"

Important

• In Fedora, the user group I found to give permission to the device, is uaccess, but in another distribution, may have other name.

• Executable permission:

We need to show that the owner of the wcoolmon executable is root user, because root will be also the owner of the service.

sudo restorecon -F -v ./wcoolmon 

Without the step above, the wcoolmon executable cant do IO in the cooler device. Not necessary in ubuntu.

• Copy the wcoolmon executable to /usr/local/bin.
• Create a systemd in /etc/systemd/system/wcoolmon.service

❯ nano /etc/systemd/system/wcoolmon.service

The service template:

[Unit]
Description=Water Cooler Monitor
After=network.target

[Service]
Type=simple
ExecStart=/usr/local/bin/wcoolmon
Restart=always
User=root

[Install]
WantedBy=multi-user.target

• Update the systemctl service list, start the service and check the status.

❯ sudo systemctl daemon-reload 
❯ sudo systemctl start wcoolmon.service 
❯ systemctl status wcoolmon.service 

You must see something like this:

❯ systemctl status wcoolmon.service 
● wcoolmon.service - Water Cooler Monitor
     Loaded: loaded (/etc/systemd/system/wcoolmon.service; enabled; preset: disabled)
    Drop-In: /usr/lib/systemd/system/service.d
             └─10-timeout-abort.conf
     Active: active (running) since Sun 2025-12-07 16:38:28 -03; 34min ago
 Invocation: 551794869fa34392b87a4521a45932bd
   Main PID: 1188 (wcoolmon)
      Tasks: 1 (limit: 18817)
     Memory: 1.8M (peak: 3.8M)
        CPU: 10.609s
     CGroup: /system.slice/wcoolmon.service
             └─1188 /usr/local/bin/wcoolmon

Dec 07 16:38:28 fedora systemd[1]: Started wcoolmon.service - Water Cooler Monitor.
Dec 07 16:38:28 fedora wcoolmon[1188]: Connected to Device: 8666

• Exemple: Running on Mancer Water Cooler.