__name__ can't be used in labels

Signed-off-by: Gregor Zeitlinger <[email protected]>

Author: zeitlinger

prometheus-metrics-model/src/main/java/io/prometheus/metrics/model/snapshots/PrometheusNaming.java

@@ -30,8 +30,6 @@ public class PrometheusNaming {
    */
   public static final String ESCAPING_KEY = "escaping";
 
-  private static final String METRIC_NAME_LABEL = "__name__";
-
   private static final Pattern METRIC_NAME_PATTERN = Pattern.compile("^[a-zA-Z_:][a-zA-Z0-9_:]*$");
 
   /** Legal characters for label names. */
@@ -290,19 +288,15 @@ public static MetricSnapshot escapeMetricSnapshot(MetricSnapshot v, EscapingSche
     List<DataPointSnapshot> outDataPoints = new ArrayList<>();
 
     for (DataPointSnapshot d : v.getDataPoints()) {
-      if (!metricNeedsEscaping(d)) {
+      if (!metricNeedsEscaping(d, scheme)) {
         outDataPoints.add(d);
         continue;
       }
 
       Labels.Builder outLabelsBuilder = Labels.builder();
 
       for (Label l : d.getLabels()) {
-        if (METRIC_NAME_LABEL.equals(l.getName())) {
-          outLabelsBuilder.label(l.getName(), escapeName(l.getValue(), scheme));
-        } else {
-          outLabelsBuilder.label(escapeName(l.getName(), scheme), l.getValue());
-        }
+        outLabelsBuilder.label(escapeName(l.getName(), scheme), l.getValue());
       }
 
       Labels outLabels = outLabelsBuilder.build();
@@ -314,13 +308,10 @@ public static MetricSnapshot escapeMetricSnapshot(MetricSnapshot v, EscapingSche
         v, escapeName(v.getMetadata().getName(), scheme), outDataPoints);
   }
 
-  static boolean metricNeedsEscaping(DataPointSnapshot d) {
+  static boolean metricNeedsEscaping(DataPointSnapshot d, EscapingScheme scheme) {
     Labels labels = d.getLabels();
     for (Label l : labels) {
-      if (l.getName().equals(METRIC_NAME_LABEL) && !isValidLegacyMetricName(l.getValue())) {
-        return true;
-      }
-      if (!isValidLegacyMetricName(l.getName())) {
+      if (needsEscaping(l.getName(), scheme)) {
         return true;
       }
     }
@@ -479,11 +470,7 @@ private static MetricSnapshot createEscapedMetricSnapshot(
    * which by definition is a noop). This method does not do any validation of the name.
    */
   public static String escapeName(String name, EscapingScheme scheme) {
-    boolean noEscapeNeeded =
-        isValidLegacyMetricName(name)
-            && !(scheme == EscapingScheme.DOTS_ESCAPING
-                && (name.contains(".") || name.contains("_")));
-    if (name.isEmpty() || noEscapeNeeded) {
+    if (name.isEmpty() || !needsEscaping(name, scheme)) {
       return name;
     }
 
@@ -547,6 +534,11 @@ public static String escapeName(String name, EscapingScheme scheme) {
     }
   }
 
+  private static boolean needsEscaping(String name, EscapingScheme scheme) {
+    return !isValidLegacyMetricName(name)
+        || (scheme == EscapingScheme.DOTS_ESCAPING && (name.contains(".") || name.contains("_")));
+  }
+
   /**
    * Unescapes the incoming name according to the provided escaping scheme if possible. Some schemes
    * are partially or totally non-roundtripable. If any error is encountered, returns the original

prometheus-metrics-model/src/test/java/io/prometheus/metrics/model/snapshots/PrometheusNamingTest.java

@@ -104,8 +104,7 @@ public void testEmptyUnitName() {
 
   @ParameterizedTest
   @MethodSource("nameIsValid")
-  public void testLabelNameIsValidUtf8(
-      String labelName, boolean utf8Valid) {
+  public void testLabelNameIsValidUtf8(String labelName, boolean utf8Valid) {
     assertMetricName(labelName, utf8Valid);
     assertLabelName(labelName, utf8Valid);
   }
@@ -128,13 +127,13 @@ static Stream<Arguments> nameIsValid() {
         Arguments.of("Avalid_23name", true),
         Arguments.of("_Avalid_23name", true),
         Arguments.of("1valid_23name", true),
-        Arguments.of("avalid_23name",  true),
-        Arguments.of("Ava:lid_23name",  true),
+        Arguments.of("avalid_23name", true),
+        Arguments.of("Ava:lid_23name", true),
         Arguments.of("a lid_23name", true),
-        Arguments.of(":leading_colon",  true),
-        Arguments.of("colon:in:the:middle",true),
+        Arguments.of(":leading_colon", true),
+        Arguments.of("colon:in:the:middle", true),
         Arguments.of("aΩz", true),
-        Arguments.of("a\ud800z",  false));
+        Arguments.of("a\ud800z", false));
   }
 
   @ParameterizedTest
@@ -369,27 +368,23 @@ private void testEscapeMetricSnapshot(
 
     DataPointSnapshot escapedData = got.getDataPoints().get(0);
     assertThat((Iterable<? extends Label>) escapedData.getLabels())
-        .isEqualTo(
-            Labels.builder()
-                .label("__name__", expectedName)
-                .label(expectedLabelName, expectedLabelValue)
-                .build());
+        .isEqualTo(Labels.builder().label(expectedLabelName, expectedLabelValue).build());
 
     assertThat(original.getMetadata().getName()).isEqualTo(name);
     assertThat(original.getMetadata().getHelp()).isEqualTo("some help text");
     assertThat(original.getDataPoints()).hasSize(1);
 
     DataPointSnapshot originalData = original.getDataPoints().get(0);
     assertThat((Iterable<? extends Label>) originalData.getLabels())
-        .isEqualTo(Labels.builder().label("__name__", name).label(labelName, labelValue).build());
+        .isEqualTo(Labels.builder().label(labelName, labelValue).build());
   }
 
   private MetricSnapshot createTestSnapshot(
       String name,
       String labelName,
       String labelValue,
       Class<? extends MetricSnapshot> snapshotType) {
-    Labels labels = Labels.builder().label("__name__", name).label(labelName, labelValue).build();
+    Labels labels = Labels.builder().label(labelName, labelValue).build();
 
     if (snapshotType.equals(CounterSnapshot.class)) {
       return CounterSnapshot.builder()