[dynatraceexporter] truncate long unmarshalable responses (open-telem…

…etry#10568)

* [dynatraceexporter] truncate long unmarshalable responses

* Update changelog

CHANGELOG.md

@@ -24,6 +24,7 @@
 - `tailsamplingprocessor`: Add support for string invert matching to `and` policy (#9553)
 - `mezemoexporter`: Add user agent string to outgoing HTTP requests (#10470)
 - `transformprocessor`: Add functions for conversion of scalar metric types (`gauge_to_sum` and `sum_to_gauge`) (#10255)
+- `dynatraceexporter`: Truncate unmarshalable responses to avoid long log lines (#10568)
 
 ### 🧰 Bug fixes 🧰
 

exporter/dynatraceexporter/metrics_exporter.go

@@ -227,7 +227,9 @@ func (e *exporter) sendBatch(ctx context.Context, lines []string) error {
 		responseBody := metricsResponse{}
 		if err := json.Unmarshal(bodyBytes, &responseBody); err != nil {
 			// if the response cannot be read, do not retry the batch as it may have been successful
-			e.settings.Logger.Error("Failed to unmarshal response from Dynatrace", zap.Error(err), zap.ByteString("body", bodyBytes))
+			bodyStr := string(bodyBytes)
+			bodyStr = truncateString(bodyStr, 1000)
+			e.settings.Logger.Error("Failed to unmarshal response from Dynatrace", zap.Error(err), zap.String("body", bodyStr))
 			return nil
 		}
 
@@ -279,6 +281,17 @@ func (e *exporter) start(_ context.Context, host component.Host) (err error) {
 	return nil
 }
 
+func truncateString(str string, num int) string {
+	truncated := str
+	if len(str) > num {
+		if num > 3 {
+			num -= 3
+		}
+		truncated = str[0:num] + "..."
+	}
+	return truncated
+}
+
 // Response from Dynatrace is expected to be in JSON format
 type metricsResponse struct {
 	Ok      int                  `json:"linesOk"`