How to parse apache error logs with Promtail?

Hello, I’m actually sending my apache logs to loki with promtail. I achieved to parse the access.log thanks to this topic : How labels in Loki can make log queries faster and easier | Grafana Labs

But I don’t understand how works the regex with promtail. So can you help me to parse this type of logs with promtail ?

[Wed Mar 03 03:08:18.252744 2021] [php7:notice] [pid 36] [client :50966]

Thank you by advance