Prometheus

It's more commonly paired with Prometheus.

Query variables

• label_names() returns a list of label names.
• label_values(label) returns a list of values for the given label name.
• label_values(metric, label) returns a list of values for the given label name in the given metric.
• metrics(regex) yields a list of metrics that match the supplied regular expression.
• query_result(query) yields a list of values for the specified query.