Concepts
Data Model
Metric and Label
Every time series is uniquely identified by its metric name and optional key-value pairs called labels.
The metric name specifies the general feature of a system that is measured (e.g. http_requests_total - the total number of HTTP requests received). It may contain ASCII letters and digits, as well as underscores and colons. It must match the regex [a-zA-Z_:][a-zA-Z0-9_:]*.
Note: The colons are reserved for user defined recording rules. They should not be used by exporters or direct instrumentation.
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.
Label names may contain ASCII letters, numbers, 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.
Label values may contain any Unicode characters.
A label with an empty label value is considered equivalent to a label that does not exist.
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