Datadog Tag Formatter

Datadog tags are key:value pairs that add metadata to metrics, logs, traces, and events. They enable filtering, grouping, and aggregating data across your infrastructure. Example: env:production, service:api, version:2.1.0.

Tag keys: must start with a letter, can contain letters, numbers, underscores, hyphens, slashes, and periods. Max 200 characters. Tag values: similar rules but can start with any character. Both key and value are normalized to lowercase. Avoid spaces — use underscores instead.

Host tags apply to a host across all metrics and are set in the Agent config or cloud integration. Metric tags are added per metric/log/trace in your code or pipelines. Both use the same key:value format.

Datadog recommends keeping tag cardinality low. High-cardinality tags (like user IDs or request IDs) with millions of unique values can cause index explosion and significantly increase your bill. Use lower-cardinality tags like env, service, version, region.