Labels enable Prometheus's dimensional data model
Any given combination of labels for the same metric name identifies a particular dimensional instantiation of that metric (for example: all HTTP requests that used the method POST to the /api/tracks handler).
The query language allows filtering and aggregation based on these dimensions.
Changing any label value, including adding or removing a label, will create a new time series.
Example of two labels:
Label names may contain:
- as well as underscores.
They must match the regex [a-zA-Z_][a-zA-Z0-9_]*.
Label names beginning with __ are reserved for internal use.
More … naming
Label values may contain any Unicode characters.
A label with an empty label value is considered equivalent to a label that does not exist.