Prometheus format problems (helidon-io#1427) Do not repeat LINE and H…

…ELP lines in Prometheus format as this is a violation that can be flagged by tools with validation enabled. This can happen for metrics with same name and different tags. We now keep track of TYPE and HELP lines added to format to avoid repetition.

metrics/metrics/src/main/java/io/helidon/metrics/HelidonConcurrentGauge.java

@@ -90,11 +90,13 @@ public void jsonData(JsonObjectBuilder builder, MetricID metricID) {
     }
 
     @Override
-    public void prometheusData(StringBuilder sb, MetricID metricID) {
+    public void prometheusData(StringBuilder sb, MetricID metricID, boolean withHelpType) {
         String name = prometheusNameWithUnits(metricID);
         final String nameCurrent = name + "_current";
-        prometheusType(sb, nameCurrent, metadata().getType());
-        prometheusHelp(sb, nameCurrent);
+        if (withHelpType) {
+            prometheusType(sb, nameCurrent, metadata().getType());
+            prometheusHelp(sb, nameCurrent);
+        }
         sb.append(nameCurrent).append(prometheusTags(metricID.getTags()))
                 .append(" ").append(prometheusValue()).append('\n');
         final String nameMin = name + "_min";

metrics/metrics/src/main/java/io/helidon/metrics/HelidonHistogram.java

@@ -71,7 +71,7 @@ public Snapshot getSnapshot() {
     }
 
     @Override
-    public void prometheusData(StringBuilder sb, MetricID metricID) {
+    public void prometheusData(StringBuilder sb, MetricID metricID, boolean withHelpType) {
         Units units = getUnits();
         String tags = prometheusTags(metricID.getTags());
         String name = metricID.getName();
@@ -84,7 +84,9 @@ public void prometheusData(StringBuilder sb, MetricID metricID) {
         // # TYPE application:file_sizes_mean_bytes gauge
         // application:file_sizes_mean_bytes 4738.231
         nameUnits = prometheusNameWithUnits(name + "_mean", unit);
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
@@ -94,7 +96,9 @@ public void prometheusData(StringBuilder sb, MetricID metricID) {
         // # TYPE application:file_sizes_max_bytes gauge
         // application:file_sizes_max_bytes 31716
         nameUnits = prometheusNameWithUnits(name + "_max", unit);
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
@@ -104,7 +108,9 @@ public void prometheusData(StringBuilder sb, MetricID metricID) {
         // # TYPE application:file_sizes_min_bytes gauge
         // application:file_sizes_min_bytes 180
         nameUnits = prometheusNameWithUnits(name + "_min", unit);
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
@@ -114,7 +120,9 @@ public void prometheusData(StringBuilder sb, MetricID metricID) {
         // # TYPE application:file_sizes_stddev_bytes gauge
         // application:file_sizes_stddev_bytes 1054.7343037063602
         nameUnits = prometheusNameWithUnits(name + "_stddev", unit);
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
@@ -125,8 +133,10 @@ public void prometheusData(StringBuilder sb, MetricID metricID) {
         // # HELP application:file_sizes_bytes Users file size
         // application:file_sizes_bytes_count 2037
         nameUnits = prometheusNameWithUnits(name, unit);
-        prometheusType(sb, nameUnits, "summary");
-        prometheusHelp(sb, nameUnits);
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "summary");
+            prometheusHelp(sb, nameUnits);
+        }
         nameUnits = prometheusNameWithUnits(name, unit) + "_count";
         sb.append(nameUnits)
                 .append(tags)

metrics/metrics/src/main/java/io/helidon/metrics/HelidonMeter.java

@@ -77,12 +77,15 @@ static HelidonMeter create(String type, Metadata metadata, Meter delegate) {
     application:requests_fifteen_min_rate_per_second 12.126
     */
     @Override
-    public void prometheusData(StringBuilder sb, MetricID metricID) {
+    public void prometheusData(StringBuilder sb, MetricID metricID, boolean withHelpType) {
         String name = metricID.getName();
         String nameUnits = prometheusNameWithUnits(name, Optional.empty()) + "_total";
         String tags = prometheusTags(metricID.getTags());
-        prometheusType(sb, nameUnits, "counter");
-        prometheusHelp(sb, nameUnits);
+
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "counter");
+            prometheusHelp(sb, nameUnits);
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")

metrics/metrics/src/main/java/io/helidon/metrics/HelidonMetric.java

@@ -56,8 +56,9 @@ interface HelidonMetric extends Metric {
      *
      * @param sb the {@code StringBuilder} used to accumulate the output
      * @param metricID the {@code MetricID} for the metric to be formatted
+     * @param withHelpType flag to control if TYPE and HELP are to be included
      */
-    void prometheusData(StringBuilder sb, MetricID metricID);
+    void prometheusData(StringBuilder sb, MetricID metricID, boolean withHelpType);
 
     /**
      * Return a name for this metric, possibly including a unit suffix.

metrics/metrics/src/main/java/io/helidon/metrics/HelidonTimer.java

@@ -106,36 +106,44 @@ public Snapshot getSnapshot() {
     }
 
     @Override
-    public void prometheusData(StringBuilder sb, MetricID metricID) {
+    public void prometheusData(StringBuilder sb, MetricID metricID, boolean withHelpType) {
         String nameUnits;
         String name = metricID.getName();
         String tags = prometheusTags(metricID.getTags());
         nameUnits = prometheusNameWithUnits(name, Optional.empty()) + "_rate_per_second";
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
                 .append(getMeanRate())
                 .append("\n");
 
         nameUnits = prometheusNameWithUnits(name, Optional.empty()) + "_one_min_rate_per_second";
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
                 .append(getOneMinuteRate())
                 .append("\n");
 
         nameUnits = prometheusNameWithUnits(name, Optional.empty()) + "_five_min_rate_per_second";
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
                 .append(getFiveMinuteRate())
                 .append("\n");
 
         nameUnits = prometheusNameWithUnits(name, Optional.empty()) + "_fifteen_min_rate_per_second";
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
@@ -147,40 +155,50 @@ public void prometheusData(StringBuilder sb, MetricID metricID) {
         Snapshot snap = getSnapshot();
 
         nameUnits = prometheusNameWithUnits(name + "_mean", unit);
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
                 .append(units.convert(snap.getMean()))
                 .append("\n");
 
         nameUnits = prometheusNameWithUnits(name + "_max", unit);
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
                 .append(units.convert(snap.getMax()))
                 .append("\n");
 
         nameUnits = prometheusNameWithUnits(name + "_min", unit);
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
                 .append(units.convert(snap.getMin()))
                 .append("\n");
 
         nameUnits = prometheusNameWithUnits(name + "_stddev", unit);
-        prometheusType(sb, nameUnits, "gauge");
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "gauge");
+        }
         sb.append(nameUnits)
                 .append(tags)
                 .append(" ")
                 .append(units.convert(snap.getStdDev()))
                 .append("\n");
 
         nameUnits = prometheusNameWithUnits(name, unit);
-        prometheusType(sb, nameUnits, "summary");
-        prometheusHelp(sb, nameUnits);
+        if (withHelpType) {
+            prometheusType(sb, nameUnits, "summary");
+            prometheusHelp(sb, nameUnits);
+        }
         nameUnits = prometheusNameWithUnits(name, unit) + "_count";
         sb.append(nameUnits)
                 .append(tags)

metrics/metrics/src/main/java/io/helidon/metrics/MetricImpl.java

@@ -214,10 +214,12 @@ void prometheusHelp(StringBuilder sb, String nameWithUnits) {
     }
 
     @Override
-    public void prometheusData(StringBuilder sb, MetricID metricID) {
+    public void prometheusData(StringBuilder sb, MetricID metricID, boolean withHelpType) {
         String nameWithUnits = prometheusNameWithUnits(metricID);
-        prometheusType(sb, nameWithUnits, metadata.getType());
-        prometheusHelp(sb, nameWithUnits);
+        if (withHelpType) {
+            prometheusType(sb, nameWithUnits, metadata.getType());
+            prometheusHelp(sb, nameWithUnits);
+        }
         sb.append(nameWithUnits).append(prometheusTags(metricID.getTags())).append(" ").append(prometheusValue()).append('\n');
     }
 

metrics/metrics/src/main/java/io/helidon/metrics/MetricsSupport.java

@@ -22,10 +22,12 @@
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.Set;
 import java.util.function.BiConsumer;
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -187,29 +189,39 @@ private void optionsAll(ServerRequest req, ServerResponse res, Registry registry
 
     static String toPrometheusData(Registry... registries) {
         return Arrays.stream(registries)
+                .filter(r -> !r.empty())
                 .map(MetricsSupport::toPrometheusData)
                 .collect(Collectors.joining());
     }
 
     static String toPrometheusData(Registry registry) {
-        return registry.stream()
-                .sorted(Comparator.comparing(Map.Entry::getKey))
-                .collect(StringBuilder::new,
-                        (sb, entry) -> toPrometheusData(sb, entry.getKey(), entry.getValue()),
-                        StringBuilder::append)
-                .toString();
+        StringBuilder builder = new StringBuilder();
+        Set<String> serialized = new HashSet<>();
+        registry.stream()
+                .sorted(Map.Entry.comparingByKey())
+                .forEach(entry -> {
+                    String name = entry.getKey().getName();
+                    if (!serialized.contains(name)) {
+                        toPrometheusData(builder, entry.getKey(), entry.getValue(), true);
+                        serialized.add(name);
+                    } else {
+                        toPrometheusData(builder, entry.getKey(), entry.getValue(), false);
+                    }
+                });
+        return builder.toString();
     }
 
     /**
      * Formats a metric in Prometheus format.
      *
      * @param metricID the {@code MetricID} for the metric to be formatted
      * @param metric the {@code Metric} containing the data to be formatted
+     * @param withHelpType flag controlling serialization of HELP and TYPE
      * @return metric info in Prometheus format
      */
-    public static String toPrometheusData(MetricID metricID, Metric metric) {
+    public static String toPrometheusData(MetricID metricID, Metric metric, boolean withHelpType) {
         final StringBuilder sb = new StringBuilder();
-        checkMetricTypeThenRun(sb, metricID, metric);
+        checkMetricTypeThenRun(sb, metricID, metric, withHelpType);
         return sb.toString();
     }
 
@@ -218,10 +230,11 @@ public static String toPrometheusData(MetricID metricID, Metric metric) {
      *
      * @param name the name of the metric
      * @param metric the {@code Metric} containing the data to be formatted
+     * @param withHelpType flag controlling serialization of HELP and TYPE
      * @return metric info in Prometheus format
      */
-    public static String toPrometheusData(String name, Metric metric) {
-        return toPrometheusData(new MetricID(name), metric);
+    public static String toPrometheusData(String name, Metric metric, boolean withHelpType) {
+        return toPrometheusData(new MetricID(name), metric, withHelpType);
     }
 
     /**
@@ -233,13 +246,15 @@ public static String toPrometheusData(String name, Metric metric) {
      *
      * @param metricID the {@code MetricID} for the metric to convert
      * @param metric the {@code Metric} to convert to Prometheus format
+     * @param withHelpType flag controlling serialization of HELP and TYPE
      * @return {@code String} containing the Prometheus data
      */
-    static void toPrometheusData(StringBuilder sb, MetricID metricID, Metric metric) {
-        checkMetricTypeThenRun(sb, metricID, metric);
+    static void toPrometheusData(StringBuilder sb, MetricID metricID, Metric metric, boolean withHelpType) {
+        checkMetricTypeThenRun(sb, metricID, metric, withHelpType);
     }
 
-    private static void checkMetricTypeThenRun(StringBuilder sb, MetricID metricID, Metric metric) {
+    private static void checkMetricTypeThenRun(StringBuilder sb, MetricID metricID, Metric metric,
+                                               boolean withHelpType) {
         Objects.requireNonNull(metric);
 
         if (!(metric instanceof HelidonMetric)) {
@@ -249,7 +264,7 @@ private static void checkMetricTypeThenRun(StringBuilder sb, MetricID metricID,
                     HelidonMetric.class.getName()));
         }
 
-        ((HelidonMetric) metric).prometheusData(sb, metricID);
+        ((HelidonMetric) metric).prometheusData(sb, metricID, withHelpType);
     }
 
     // unit testable
@@ -418,7 +433,7 @@ private void getOne(ServerRequest req, ServerResponse res, Registry registry) {
                         res.send(builder.build());
                     } else if (mediaType == MediaType.TEXT_PLAIN) {
                         final StringBuilder sb = new StringBuilder();
-                        entry.getValue().prometheusData(sb, entry.getKey());
+                        entry.getValue().prometheusData(sb, entry.getKey(), true);
                         res.send(sb.toString());
                     } else {
                         res.status(Http.Status.NOT_ACCEPTABLE_406);

metrics/metrics/src/test/java/io/helidon/metrics/HelidonCounterTest.java

@@ -109,14 +109,14 @@ void testPrometheusData() {
                 + "# HELP base_theName_total theDescription\n"
                 + "base_theName_total{a=\"b\",c=\"d\"} 17\n";
 
-        counter.prometheusData(sb, counterID);
+        counter.prometheusData(sb, counterID, true);
         assertThat(sb.toString(), is(expected));
 
         expected = "# TYPE base_theName_total counter\n"
                 + "# HELP base_theName_total theDescription\n"
                 + "base_theName_total 49\n";
         sb = new StringBuilder();
-        wrappingCounter.prometheusData(sb, wrappingCounterID);
+        wrappingCounter.prometheusData(sb, wrappingCounterID, true);
         assertThat(sb.toString(), is(expected));
     }
 

metrics/metrics/src/test/java/io/helidon/metrics/HelidonHistogramTest.java

@@ -210,7 +210,7 @@ void testJson() {
     @Test
     void testPrometheus() throws IOException, ParseException {
         final StringBuilder sb = new StringBuilder();
-        histoInt.prometheusData(sb, histoIntID);
+        histoInt.prometheusData(sb, histoIntID, true);
         parsePrometheusText(new LineNumberReader(new StringReader(sb.toString())).lines())
                 .forEach(entry -> assertThat("Unexpected value checking " + entry.getKey(),
                                     EXPECTED_PROMETHEUS_RESULTS.get(entry.getKey()),

metrics/metrics/src/test/java/io/helidon/metrics/HelidonMeterTest.java

@@ -133,7 +133,7 @@ void testJson() {
     @Test
     void testPrometheus() {
         final StringBuilder sb = new StringBuilder();
-        meter.prometheusData(sb, meterID);
+        meter.prometheusData(sb, meterID, true);
         String data = sb.toString();
 
         assertThat(data, startsWith(EXPECTED_PROMETHEUS_START));

metrics/metrics/src/test/java/io/helidon/metrics/HelidonTimerTest.java

@@ -198,7 +198,7 @@ void testJson() {
     @Test
     void testPrometheus() {
         final StringBuilder sb = new StringBuilder();
-        dataSetTimer.prometheusData(sb, dataSetTimerID);
+        dataSetTimer.prometheusData(sb, dataSetTimerID, true);
         final String prometheusData = sb.toString();
         assertThat(prometheusData, startsWith("# TYPE application_response_time_rate_per_second gauge\n"
                                                       + "application_response_time_rate_per_second 200.0\n"