Caching exporter is modified version of mtail with several additions to collect metrics stored in a plist file. Caching Exporter collects metrics from the following locations:

• /Library/Server/Caching/Config/Config.plist
• /Library/Server/Caching/Logs/LastState.plist
• /Library/Server/Caching/Logs/Debug.log

sudo ./caching_exporter -progs ./progs --logs /Library/Server/Caching/Logs/Debug.log

Now point Prometheus at localhost:3903/metrics to collect the data exposed by Caching exporter.

Progs are files that contain regex rules for parsing data from log files into time series. This is the functionality enabled by mtail and can be extended by rewriting or adding our own rules in the progs folder. An example:

# simple line counter
counter line_count
/$/ {
    line_count++
}