The 'matches' parameter for the Promtail journal scraper is not documented in the config reference

[adeverteuil]

The Scraping page mentions a 'matches' parameter for the journal scraper.

https://grafana.com/docs/loki/latest/clients/promtail/scraping/#journal-scraping-linux-only

The matches field adds journal filters. If multiple filters are specified matching different fields, the log entries are filtered by both, if two filters apply to the same field, then they are automatically matched as alternatives.

The example shows this value is a string. It's not clear how to provide multiple filters. Are they space separated? Comma separated? Is quoting supported? Can it be a YAML list or dict?

Also, the 'matches' field is not mentioned in the Configuration reference page.
https://grafana.com/docs/loki/latest/clients/promtail/configuration/#journal

[cbu27]

I was also confused due to the missing documentation for "matches" but i found out, that you have to provide parameters like journalctl command line arguments.

e.g. if you filter for special units

matches: _SYSTEMD_UNIT=XXX.service _SYSTEMD_UNIT=XXX.service _SYSTEMD_UNIT=XXX.service

Please note, that you have to grant access to the promtail user for the journal.