Power Saving

Wake-on-LAN #

When the cluster is setup it is often not needed to have the machines powered when there is no job in the queue.

What you can setup is a simple Wake-on-LAN script that will only wakeup the machines when there is job in the queue waiting.

For examplary purposes we document a script here that works on a low power Raspberry PI that we have active in our local network, but any simple microcontroller that has HTTP capabilites will.

#!/bin/bash
# filename: wake_machine.sh


# Install this script as a cronjob
# m h  dom mon dow   command
# 15\/* * * * * bash /home/pi/wake_machine.sh

## You need the wakeonlan and the jq package installed
## sudo apt install wakeonlan jq -y


output=$(curl "https://api.green-coding.io/v1/jobs?machine_id=7&state=WAITING" --silent  |  jq '.["data"] | length')

# Check if the output is a specific string
if [[ "$output" =~ ^[0-9]+$ && $output -ne 0 ]]; then
    echo "Having waiting jobs. Sending Wake on LAN magic packet ..."

    # Please replace '80:1B:3E:A8:26:19' with your machines MAC address
    # Using port 1234 will usually work. If you run into issues try port 9, 8 or 7 also
    # Do not use the IP address of the machine, but the broadcast address (usually the last number block must be replaced by 255)
    wakeonlan -i 10.1.0.255 -p 1234 80:1B:3E:A8:26:19

    echo "Wake on LAN magic packet send!"
else
    echo "Command output is '0'. No other program started."
fi

Turning machine off on empty queue #

To use this functionality you should have Wake-on-LAN activated.

You can then set the shutdown_on_job_no to True and the machine will turn off when the job queue is empty.

cluster:
  client:
    ...  
    shutdown_on_job_no: True

In order for the shutdown to be triggered by the client.py you must allow the sudo call without password in an /etc/sudoers.d/ entry.

Example:

echo 'ALL ALL=(ALL) NOPASSWD:/usr/bin/systemctl suspend' | sudo tee /etc/sudoers.d/green-coding-shutdown
sudo chmod 500 /etc/sudoers.d/green-coding-shutdown