# Cross compile and upload to your raspberry:
$ GOARCH=arm64 go build && scp pi-temp raspberry:/usr/local/bin/pi-temp
pi-temp                                                    100% 9619KB   9.4MB/s   00:01

# Log into your Pi:
$ ssh raspberry

# Helpful help output is helpful:
Usage of pi-temp:
  -addr string
    	The address to listen on for HTTP requests. (default ":8080")
  -debug
    	Enable debug output.
  -file string
    	Path to the thermal zone file. (default "/sys/class/thermal/thermal_zone0/temp")
  -interval duration
    	The interval at which the temperature is checked. (default 10s)

# Run it:
$ pi-temp -debug
Checking temperature every 10s from "/sys/class/thermal/thermal_zone0/temp"
CPU temperature: 55.306°C
CPU temperature: 54.768°C
CPU temperature: 54.768°C
CPU temperature: 54.768°C
…

# Upload systemd unit file:
$ scp pi-temp.service raspberry:/etc/systemd/system/pi-temp.service

# Log into your Pi:
$ ssh raspberry

# Enable service to start on boot:
$ systemctl enable pi-temp.service

# Start pi-temp service now:
$ systemctl start pi-temp

# Check its running:
$ systemctl status pi-temp
● pi-temp.service - Prometheus Temperature Monitor
   Loaded: loaded (/etc/systemd/system/pi-temp.service; enabled; vendor preset: disabled)
   Active: active (running) since Sun 2018-08-12 23:20:18 CEST; 1s ago
 Main PID: 7886 (pi-temp)
    Tasks: 7 (limit: 1053)
   Memory: 1.3M
   CGroup: /system.slice/pi-temp.service
           └─7886 /usr/local/bin/pi-temp -interval=10s -addr=:9101

Aug 12 23:24:49 rasputin systemd[1]: Started Prometheus Temperature Monitor.
Aug 12 23:24:49 rasputin pi-temp[7953]: Starting pi-temp web server at ":9101"
Aug 12 23:24:49 rasputin pi-temp[7953]: If you want to see more verbose log run with -debug