As I'm currently participating on Grafana observability stack Plan & Design exercise, I would like to know what is the average size of log line ingested into the observability stack. Such information is pretty useful for capacity planning and sizing.
Log lines are stored on Loki log database and Loki itself is exposing metrics into Mimir time series database for self monitoring purpose. Grafana Loki and Promtail metrics are documented here.
The following formula calculates average size of log message:
sum(rate(loki_distributor_bytes_received_total [7d])) / sum(rate(loki_distributor_lines_received_total [7d]))
The result is visualized in the screenshot below.
Hope this tip will be useful for someone else.