Merge pull request #536 from wavefrontHQ/K8SSAAS-1242-v2-add-dropped-metrics-logic-to-readme

change readme

Author: yuqijin-cb

README.md

@@ -37,6 +37,24 @@ Commonly used `make` options include:
 * `build` that creates a local executable
 * `container` that uses a docker container to build for consistency and reproducability 
 
+## Troubleshooting Dropped Metrics
+
+Formerly, we would see the following error in the proxy logs when a metric has too many tags: `Too many point tags`.
+However, logic has been added to the collector to automatically drop tags in priority order
+to ensure that metrics make it through to the proxy and no longer cause this error.
+This is the order of the logic used to drop tags:
+1. Explicitly excluded tags (from `tagExclude` config).
+   Refer [here](https://github.com/wavefrontHQ/wavefront-operator-for-kubernetes/blob/main/deploy/kubernetes/scenarios/wavefront-full-config.yaml) for an example scenario.
+1. Tags are empty or are interpreted to be empty (`"tag.key": ""`, `"tag.key": "-"`, or `"tag.key": "/"`).
+1. Tags are explicitly excluded
+   (`"namespace_id": "..."`, `"host_id": "..."`, `"pod_id": "..."`, or `"hostname": "..."`).
+1. Tag **values** are duplicated, and the shorter key is kept
+   (`"tag.key": "same value"` is kept instead of `"tag.super.long.key": "same value"`).
+1. Tag key matches `alpha.*` or `beta.*`, after keys have been sorted
+   (e.g. `"alpha.eksctl.io/nodegroup-name": "arm-group"` or `"beta.kubernetes.io/arch": "amd64"`).
+1. (As a last resort) tag key matches IaaS-specific tags, after keys have been sorted
+   (`"kubernetes.azure.com/agentpool": "agentpool"`, `"topology.gke.io/zone": "us-central1-c"`, `"eksctl.io/nodegroup-name": "arm-group"`, etc.).
+
 ## Contributing
 Public contributions are always welcome. Please feel free to report issues or submit pull requests.