Outer join by slightly different label values

Hi Community,

Im trying to outer join query results by “slightly different” instance labels.

The data source is Prometheus with regular jobs for VM groups and a Blackbox Exporter ICMP job for all VMs.

The regular prometheus querys are containing the FQDN + the port (vmname.mycompany.com:9100) as the instance value while the Blackbox Exporter’s probe_success is containing just the FQDN (vmname.mycompany.com).

Outer join by instance provides me two rows for each endpoint. Any ideas how to solve this?

An override for the instance column with a value mapping regex condition “:9100” → empty does not do the trick.

Grafana v8.3.1 (8d38082755) is being used.

Thank you in advance.