What best practices are recommended for naming metrics and tags?

Datadog recommends certain best practices for naming metrics, tags, and services.

Rules and best practices for naming metrics

  • Metric names must start with a letter.
  • Can only contain ASCII alphanumerics, underscores, and periods. Other characters are converted to underscores.
  • Should not exceed 200 characters (though less than 100 is generally preferred from a UI perspective)
  • Unicode is not supported.
  • It is recommended to avoid spaces.

Metrics reported by the Agent are in a pseudo-hierarchical dotted format, for example: http.nginx.response_time. This is described as pseudo-hierarchical because a hierarchy is not actually enforced, but the structure is used to infer certain relationships, for example: “I see hostA and hostB are reporting http.nginx.*, those must be web frontends”).

Note: Metric names are case sensitive in Datadog.

Rules and best practices for naming tags

As a best practice, Datadog recommends using unified service tagging when assigning tags. Unified service tagging ties Datadog telemetry together through the use of three standard tags: env, service, and version. To learn how to configure your environment with unified tagging, see Unified service tagging.

  • Tags must start with a letter.
  • May contain alphanumerics, underscores, minuses, colons, periods, and slashes. Other characters are converted to underscores.
  • A trailing underscore is removed, whether if it originated from a converted character or if it was in the original tag value.
  • Contiguous underscores are reduced to a single underscore.
  • Tags can be up to 200 characters long and support Unicode.
  • Tags are converted to lowercase.
  • For optimal functionality, it is recommended to use the key:value syntax.

Examples of commonly used metric tag keys are instance, name, and role.

Further Reading