grok_exporter is the way to extract metrics from unstructured logs: github.com/fstab/grok_exporter/blob/release/CONFIG.md
It supports glob patterns in file names but not in directory names.
KStars creates directories daily, for example my latest log file is ~/.local/share/kstars/logs/2021-02-25/log_20-59-31.txt
Wonder how to workaround that.