A Trafficlight-style status display for the Checkmk monitoring solution.

... is the interface to the Checkmk in memory stateDB used to gather the status data. A description can be found here: https://docs.checkmk.com/latest/en/livestatus.html

A Linux board with three i/o ports and a LAN interface is used as platform. For me a wired LAN interface and a small form factor was important. This is the board I've used: http://www.orangepi.org/orangepizero/

I've chosen Armbian as OS: https://www.armbian.com/orange-pi-zero/

Downloaded and installed at a Sandisk 16GB uSD card as described there. Installed Armbian version:

VERSION="20.04.1 LTS (Focal Fossa)"
PRETTY_NAME="Armbian 20.08 Focal"
VERSION_ID="20.04"

update the Linux system and compile the GPIO library. The used version from "nvl1109" is a adapted to the OrangePi Zero.

root@orangepizero:~# 
armbian-config
apt update
apt upgrade
apt install python3-dev
apt install python3-sdnotify #for watchdog
mkdir /opt/trafficlight/
cd /opt/trafficlight/
git clone https://github.com/nvl1109/orangepi_zero_gpio.git
cd orangepi_zero_gpio/
python3 setup.py install

Installed Python version at day of writing: Python 3.8.2

Copy the Python program "checkstatus.py" to the folder /opt/trafficlight and make it executable:

root@orangepizero:~#
chmod +x /opt/trafficlight/checkstatus.py

Tasks of the program:

• Query Livestatus
• calculate and set LED Status
• Loop every [INTERVAL] seconds.

created a systemd service with watchdog functionality: /lib/systemd/system/trafficlight.service or for SLES: /usr/lib/systemd/system/trafficlight.service

[Unit]
Description=Trafficlight service
After=multi-user.target
[Service]
#Type=simple
WatchdogSec=30s
Restart=on-failure
StartLimitInterval=5min
StartLimitBurst=4
StartLimitAction=reboot-force
WorkingDirectory=/opt/trafficlight
ExecStart=/usr/bin/python3 /opt/trafficlight/checkstatus.py
[Install]
WantedBy=multi-user.target

Enable and start:

sudo systemctl daemon-reload
sudo systemctl enable trafficlight
sudo systemctl start trafficlight

Three queries are necessary:

1. check if hosts, which relates to certain 'contact_groups' are unacknowledged (and not in scheduled maintanance) in status CRITICAL or WARN
2. check if services, which relates to hosts in certain 'contact_groups' are unacknowledged (and not in scheduled maintanance) in status CRITICAL
3. check if services, which relates to hosts in certain 'contact_groups' are unacknowledged (and not in scheduled maintanance) in status WARN

1. st Query's result is >0 = red Light on
2. nd Query's result is >0 = red Light on
3. rd Query's result is >0 = yellow Light on

If none of the queries returns a number greater 0, the green light is turned on and all other lights are turned off.

Enable Livestatus API access in Checkmk from network (TCP/IP):

[sitename-user]@checkmk server:~#
omd stop;omd config set LIVESTATUS_TCP on;omd config set LIVESTATUS_TCP_ONLY_FROM '172.18.1.91';omd start

I've used these pins as output for the LEDs:

• RED LED: Port PG6
• YELLOW LED: Port PG7
• GREEN LED: Port PA7

https://github.com/nvl1109/orangepi_zero_gpio

I've soldered a 7-pin male header to the OrangePi Zero and the female opposite to the flexible cables. Two pins (1 und 7) are unused. they are connected to the +5V and GND and could be used to feed the power to the board. Currently unused in my case.

I've decided to choose a 12V/0.5A feeding via Ethernet cable spare pins. This should be enough for 5 to 15 meters cable length depending on the cable quality. If you need to provide the power over a longer cable, you should use a higher voltage. But ATTENTION: two resistors must be removed from the OrangePi Zero board. They are 750 Ohms parallel to the PoE input and would overheat at such high voltages. See documentation here I've removed them anyway. A stepdown (buck) converter is needed to provide the neccesary 5V for the OrangePi Zero.

A passive PoE injector is used to provide the 12V.

The PoE pin of the Orangepi Zero is wired to the input of the stepdown converter. The output of of the stepdown converter is wired to the 5V pin of the Orangepizero.

Also, I've added a Diode 1N4007 in series between 12V+ PoE and Vin of the buck converter as a protection in case of wrong polarity.

+12V PoE o----=>|----o +Vin buck converter +5V Vout o----------o +5V OrangePi Zero
             1N4007
             
  0V PoE o-----------o -Vin buck converter -5V Vout o----------o GND OrangePi Zero

Power consumtion: The maximum power consumtion I saw at the 12V side was 3.4 Watt during bootup when all LEDs (external, trafficlight) are on. After bootup a maximum of 1.6 Watts is drawn if all LEDs are on.

Here I bought the buck converter (no affiliate link ;-) ): https://www.electrodragon.com/product/dc-dc-step-power-module-mp1584-fixed-output/

Use the fixed-output voltage version. These with variable output voltage are unreliable (at least the cheap ones).

If you like you can use the file Ampelfuss.stl as 3D print template for the new base of the Trafficlight holding the OrangePi Zero.

Here are some more pictures taken during the realisation of the project.

(The trafficlight was delivered with a tiny microcontroller and driver transistors at the LED board)

(I've removed the microcontroller and connected the OrangePi Zero through flexible cables to the solder pads where the output pins of the removed microcontroller where)

(Fixed the wires with hot glue)

(LED board remounted at backside)

(View inside the head, baseplate mounted. Originally it had a MicroUSB port and I've extended the smaller hole to a rectangular to fit the RJ45 plug.)

(In action prior to mounting the base plate) (passive PoE injector used)