grafana + prometheus conditional query

I have this query:

sum by (name) (rate(container_cpu_usage_seconds_total{image!="",
container_label_org_label_schema_group="$group"}
[1m])) / scalar(count(node_cpu_seconds_total{mode="$mode"})) * 100

$group is a list and values can be 'monitoring', 'web', or 'all'.

When $group is 'web', I'd like to replace $group with empty string. So the container_label_org_label_schema_group condition should be:

container_label_org_label_schema_group  = ''

When $group is 'all', then i want to match where container_label_org_label_schema_group is equal to 'monitoring' or empty string. Effectively something like:

container_label_org_label_schema_group  = '"monitoring"|""'

Not sure how to do do this with the promQL. It doesn't seem like the use of some AND operators to do pseudo IFs is working here. I'm thinking maybe substitution could be an option. But I don't not have success there either.

Not really. In grafana you can specify label for every value of you variable: it will be shown in drop down. But when substituted corresponding value will be used instead.

To do it you provide values for variable in format label1 : value1, label2 : value2.

And then simply use it in query like $example

For your exact problem use variable with the following values:

web :  , monitoring : monitoring, all : monitoring|

Please notice double space between first colon and comma.