Core: Support prometheus namespace and subsystem prefixes (prebid#1802)

docs/config-app.md

@@ -249,8 +249,11 @@ For `console` backend type available next options:
 - `metrics.console.interval` - interval in seconds between successive sending metrics.
 
 For `prometheus` backend type available next options:
-- `metrics.prometheus.port` - if a port is specified a prometheus reporter will start on that port 
-- `metrics.prometheus.labels.enabled` - If set to `true` it enables tags/labels for prometheus metrics instead of including them in the metrics path
+- `metrics.prometheus.enabled` - if equals to `true` then prometheus reporter will be started
+- `metrics.prometheus.port` - prometheus reporter port
+- `metrics.prometheus.namespace` - optional namespace prefix for metrics
+- `metrics.prometheus.subsystem` - optional subsystem prefix for metrics
+- `metrics.prometheus.custom-labels-enabled` - If set to `true` it enables tags/labels for prometheus metrics instead of including them in the metrics path
 
 It is possible to define how many account-level metrics will be submitted on per-account basis.
 See [metrics documentation](metrics.md) for complete list of metrics submitted at each verbosity level.

src/main/java/org/prebid/server/metric/prometheus/NamespaceSubsystemSampleBuilder.java

@@ -0,0 +1,47 @@
+package org.prebid.server.metric.prometheus;
+
+import io.prometheus.client.Collector;
+import io.prometheus.client.dropwizard.samplebuilder.SampleBuilder;
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.List;
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+public class NamespaceSubsystemSampleBuilder implements SampleBuilder {
+
+    private static final String VALID_PREFIX_REGEX = "[a-zA-Z_:]?[a-zA-Z0-9_:]*";
+
+    private final SampleBuilder delegate;
+    private final String prefix;
+
+    public NamespaceSubsystemSampleBuilder(SampleBuilder sampleBuilder, String namespace, String subsystem) {
+        delegate = Objects.requireNonNull(sampleBuilder);
+        prefix = toPrefix(namespace) + toPrefix(subsystem);
+
+        final Pattern prefixPattern = Pattern.compile(VALID_PREFIX_REGEX);
+        if (!prefixPattern.matcher(prefix).matches()) {
+            throw new IllegalArgumentException(String.format(
+                    "Invalid prefix: %s, namespace and subsystem should match regex: %s", prefix, VALID_PREFIX_REGEX));
+        }
+    }
+
+    @Override
+    public Collector.MetricFamilySamples.Sample createSample(String dropwizardName,
+                                                             String nameSuffix,
+                                                             List<String> additionalLabelNames,
+                                                             List<String> additionalLabelValues,
+                                                             double value) {
+
+        return delegate.createSample(
+                prefix + dropwizardName,
+                nameSuffix,
+                additionalLabelNames,
+                additionalLabelValues,
+                value);
+    }
+
+    private static String toPrefix(String value) {
+        return StringUtils.isNotEmpty(value) ? value + "_" : "";
+    }
+}

src/main/java/org/prebid/server/spring/config/VertxConfiguration.java

@@ -8,6 +8,7 @@
 import io.vertx.ext.dropwizard.Match;
 import io.vertx.ext.dropwizard.MatchType;
 import io.vertx.ext.web.handler.BodyHandler;
+import org.prebid.server.spring.config.metrics.MetricsConfiguration;
 import org.prebid.server.vertx.ContextRunner;
 import org.prebid.server.vertx.LocalMessageCodec;
 import org.springframework.beans.factory.annotation.Value;