Fix NPE when configuring global Prometheus labels

palantir · Aug 11, 2023 · f5e077f · f5e077f
1 parent b0cabda
commit f5e077f
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Showing 2 changed files with 8 additions and 2 deletions.
diff --git a/appmetrics/emitter/prometheus/collector.go b/appmetrics/emitter/prometheus/collector.go
@@ -174,12 +174,13 @@ func (c *Collector) descFromName(name string, help string) func(string) *prometh
 // labelsFromName extracts the labels from a metric name and returns the
 // sanitized base name and the sanitized labels.
 func labelsFromName(name string) (string, prometheus.Labels) {
+	labels := make(prometheus.Labels)
+
 	start := strings.IndexRune(name, '[')
 	if start < 0 || name[len(name)-1] != ']' {
-		return sanitizeName(name), nil
+		return sanitizeName(name), labels
 	}
 
-	labels := make(prometheus.Labels)
 	labelPairs := strings.Split(name[start+1:len(name)-1], ",")
 	for _, pair := range labelPairs {
 		key, value, ok := strings.Cut(strings.TrimSpace(pair), ":")

diff --git a/appmetrics/emitter/prometheus/collector_test.go b/appmetrics/emitter/prometheus/collector_test.go
@@ -87,15 +87,20 @@ timer_seconds_count 0
 
 		counterA := metrics.NewRegisteredCounter("counter[subsystem:a,role:server]", r)
 		counterB := metrics.NewRegisteredCounter("counter[subsystem:b,role:server]", r)
+		counterC := metrics.NewRegisteredCounter("unlabeled_counter", r)
 
 		counterA.Inc(1)
 		counterB.Inc(2)
+		counterC.Inc(3)
 
 		expected := `
 # HELP counter metrics.Counter
 # TYPE counter untyped
 counter{role="server",subsystem="a",test="labels"} 1
 counter{role="server",subsystem="b",test="labels"} 2
+# HELP unlabeled_counter metrics.Counter
+# TYPE unlabeled_counter untyped
+unlabeled_counter{test="labels"} 3
 `
 
 		if err := testutil.CollectAndCompare(c, strings.NewReader(expected)); err != nil {