Limit unbound label cardinality on request errors

This converts all request errors to the string `<error>` instead of passing the full error string. Error strings can have arbitrary values and thus have a cardinality that is not suitable for a metric use case.

Limit unbound label cardinality on request errors
a247736f · Fabian Reinartz · 68a7c2c6 · a247736f
Commit a247736f authored Nov 12, 2016 by Fabian Reinartz
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request.go pkg/client/restclient/request.go +3 -2

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--- a/pkg/client/restclient/request.go
+++ b/pkg/client/restclient/request.go
@@ -693,9 +693,10 @@ func updateURLMetrics(req *Request, resp *http.Response, err error) {
 		url = req.baseURL.Host
 	}

-	// If we have an error (i.e. apiserver down) we report that as a metric label.
+	// Errors can be arbitrary strings. Unbound label cardinality is not suitable for a metric
+	// system so we just report them as `<error>`.
 	if err != nil {
-		metrics.RequestResult.Increment(err.Error(), req.verb, url)
+		metrics.RequestResult.Increment("<error>", req.verb, url)
 	} else {
 		//Metrics for failure codes
 		metrics.RequestResult.Increment(strconv.Itoa(resp.StatusCode), req.verb, url)