How to use Grafana dashboard variable in another variables regex?

Question

I created a Grafana dashboard variable and tried to filter the values via the regex field. This works for static regex definition.

I would now like to use another variable inside the regex which provides the regex value.

So the regex field should look somehow like: /$theRealRegexVar/

I tried it with many different versions like /${theRealRegexVar}/ or /[[theRealRegexVar]]/ but it seems not to work.

Does it work somehow or is it simply impossible?

Update

The datasource is prometheus.

The regex would be a regex ;-) (for example "^.*$" - however the user would provide it in the other variable)

Answer 1

Don't know, if an answer is still relevant. But there are two options:

1. Use $theRealRegexVar directly in the query that delivers the values of your dashboard variable. For sure this only applies if your variable is a query.
2. Apply a format option on $theRealRegexVar, see https://grafana.com/docs/grafana/latest/variables/advanced-variable-format-options/. A similar task worked for me with :raw, so in your case put ${theRealRegexVar:raw} into the regex field.