Add support for the Strimzi Metrics Reporter

CHANGELOG.md

@@ -7,6 +7,14 @@
 * Dropped support for OpenAPI v2 Swagger specification.
   * The `/openapi/v2` endpoint returns HTTP 410 Gone.
   * Both the `/openapi` and `/openapi/v3` endpoints return the OpenAPI v3 definition of the bridge REST API.
+* Added support for the [Strimzi Metrics Reporter](https://github.com/strimzi/metrics-reporter) metrics.
+  * This is a Kafka plugin that directly exports metrics in Prometheus format without passing through JMX, and can be enabled by setting `bridge.metrics=strimziMetricsReporter`.
+  * The JMX Exporter metrics can still be enabled by setting `bridge.metrics=jmxPrometheusExporter`.
+
+### Changes, deprecations and removals
+
+* `KAFKA_BRIDGE_METRICS_ENABLED` configuration has been deprecated.
+  In order to keep the current behaviour and use JMX Exporter, the `bridge.metrics` property has to be set to `jmxPrometheusExporter`.
 
 ## 0.31.1
 

bin/docker/kafka_bridge_config_generator.sh

@@ -1,16 +1,37 @@
 #!/usr/bin/env bash
 
+if [ -n "$STRIMZI_METRICS" ]; then
+    BRIDGE_METRICS="bridge.metrics=${STRIMZI_METRICS}"
+fi
+
 if [ -n "$STRIMZI_TRACING" ]; then
     BRIDGE_TRACING="bridge.tracing=${STRIMZI_TRACING}"
 fi
 
 BRIDGE_PROPERTIES=$(cat <<-EOF
 #Bridge configuration
 bridge.id=${KAFKA_BRIDGE_ID}
+${BRIDGE_METRICS}
 ${BRIDGE_TRACING}
 EOF
 )
 
+if [ -n "$KAFKA_BRIDGE_METRICS_JMX_CONFIG" ]; then
+    METRICS_JMX_PROPERTIES=$(cat <<EOF
+#JMX Exporter configuration
+bridge.metrics.jmx.exporter.config.path=${KAFKA_BRIDGE_METRICS_JMX_CONFIG}
+EOF
+)
+fi
+
+if [ -n "$KAFKA_BRIDGE_METRICS_SMR_CONFIG" ]; then
+    METRICS_SMR_PROPERTIES=$(cat <<EOF
+#Strimzi Reporter configuration
+${KAFKA_BRIDGE_METRICS_SMR_CONFIG}
+EOF
+)
+fi
+
 SECURITY_PROTOCOL=PLAINTEXT
 
 if [ "$KAFKA_BRIDGE_TLS" = "true" ]; then
@@ -163,6 +184,9 @@ EOF
 PROPERTIES=$(cat <<EOF
 $BRIDGE_PROPERTIES
 
+$METRICS_JMX_PROPERTIES
+$METRICS_SMR_PROPERTIES
+
 $KAFKA_PROPERTIES
 
 $ADMIN_CLIENT_PROPERTIES

config/application.properties

@@ -1,5 +1,17 @@
 #Bridge related settings
 bridge.id=my-bridge
+
+# uncomment the following line to enable JMX Exporter metrics, check the documentation for more details
+#bridge.metrics=jmxPrometheusExporter
+# optionally, you can also set a custom configuration file
+#bridge.metrics.jmx.exporter.config.path=/path/to/my-jmx-exporter-config.yaml
+
+# uncomment the following lines to enable Strimzi Reporter metrics, check the documentation for more details
+#bridge.metrics=strimziMetricsReporter
+#kafka.metric.reporters=io.strimzi.kafka.metrics.KafkaPrometheusMetricsReporter
+#kafka.prometheus.metrics.reporter.listener.enable=false
+#kafka.prometheus.metrics.reporter.allowlist=.*
+
 # uncomment the following line (bridge.tracing) to enable OpenTelemetry tracing, check the documentation for more details
 #bridge.tracing=opentelemetry
 

documentation/assemblies/assembly-kafka-bridge-config.adoc

@@ -8,11 +8,13 @@
 [role="_abstract"]
 Configure a deployment of the Kafka Bridge using configuration properties.
 Configure Kafka and specify the HTTP connection details needed to be able to interact with Kafka.
+It is possible to enable metrics in Prometheus format with JMX Prometheus Exporter or Strimzi Metrics Reporter.
 You can also use configuration properties to enable and use distributed tracing with the Kafka Bridge.
 Distributed tracing allows you to track the progress of transactions between applications in a distributed system.
 
 NOTE: Use the `KafkaBridge` resource to configure properties when you are xref:overview-components-running-kafka-bridge-cluster-{context}[running the Kafka Bridge on Kubernetes].
 
 include::modules/proc-configuring-kafka-bridge.adoc[leveloffset=+1]
-include::modules/proc-configuring-kafka-bridge-metrics.adoc[leveloffset=+1]
-include::modules/proc-configuring-kafka-bridge-tracing.adoc[leveloffset=+1]
+include::modules/proc-configuring-kafka-bridge-jmx-metrics.adoc[leveloffset=+1]
+include::modules/proc-configuring-kafka-bridge-smr-metrics.adoc[leveloffset=+1]
+include::modules/proc-configuring-kafka-bridge-tracing.adoc[leveloffset=+1]

documentation/modules/proc-configuring-kafka-bridge-jmx-metrics.adoc

@@ -0,0 +1,33 @@
+[id='proc-configuring-kafka-bridge-jmx-metrics-{context}']
+= Configuring JMX Exporter metrics
+
+[role="_abstract"]
+Enable metrics for the Kafka Bridge by setting the `bridge.metrics` configuration.
+
+.Prerequisites
+
+* xref:proc-downloading-kafka-bridge-{context}[The Kafka Bridge installation archive is downloaded].
+
+.Procedure
+
+. Set the `bridge.metrics` configuration to `jmxPrometheusExporter`.
++
+.Configuration for enabling metrics
+
+[source,properties]
+----
+bridge.metrics=jmxPrometheusExporter
+----
++
+Optionally, you can set a custom JMX Exporter configuration file using the `bridge.metrics.jmx.exporter.config.path` property.
+If this is not set, a default configuration will be applied.
+
+. Run the Kafka Bridge script to enable metrics.
++
+.Running the Kafka Bridge to enable metrics
+[source,shell]
+----
+./bin/kafka_bridge_run.sh --config-file=<path>/application.properties
+----
++
+With metrics enabled, you can use `GET /metrics` with the `/metrics` endpoint to retrieve Kafka Bridge metrics in Prometheus format.

documentation/modules/proc-configuring-kafka-bridge-smr-metrics.adoc

@@ -0,0 +1,36 @@
+[id='proc-configuring-kafka-bridge-smr-metrics-{context}']
+= Configuring Strimzi Metrics Reporter metrics
+
+[role="_abstract"]
+Enable metrics for the Kafka Bridge by setting the `bridge.metrics` configuration.
+
+.Prerequisites
+
+* xref:proc-downloading-kafka-bridge-{context}[The Kafka Bridge installation archive is downloaded].
+
+.Procedure
+
+. Set the `bridge.metrics` configuration to `strimziMetricsReporter` and related configuration.
++
+.Configuration for enabling metrics
+
+[source,properties]
+----
+bridge.metrics=strimziMetricsReporter
+kafka.metric.reporters=io.strimzi.kafka.metrics.KafkaPrometheusMetricsReporter
+kafka.prometheus.metrics.reporter.listener.enable=false
+kafka.prometheus.metrics.reporter.allowlist=.*
+----
++
+You can add any plugin configuration to the Bridge properties file using the `kafka.` prefix.
+See the https://github.com/strimzi/metrics-reporter[Strimzi Metrics Reporter documentation] for more details.
+
+. Run the Kafka Bridge script to enable metrics.
++
+.Running the Kafka Bridge to enable metrics
+[source,shell]
+----
+./bin/kafka_bridge_run.sh --config-file=<path>/application.properties
+----
++
+With metrics enabled, you can use `GET /metrics` with the `/metrics` endpoint to retrieve Kafka Bridge metrics in Prometheus format.

pom.xml

@@ -115,6 +115,7 @@
 		<checkstyle.version>10.12.2</checkstyle.version>
 		<hamcrest.version>2.2</hamcrest.version>
 		<junit.version>5.8.2</junit.version>
+		<mockito.version>4.11.0</mockito.version>
 		<maven-jar-plugin.version>3.3.0</maven-jar-plugin.version>
 		<maven-surefire-plugin.version>3.0.0-M7</maven-surefire-plugin.version>
 		<maven-failsafe-plugin.version>3.0.0-M7</maven-failsafe-plugin.version>
@@ -131,6 +132,7 @@
 		<spotbugs.version>4.7.3</spotbugs.version>
 		<maven.spotbugs.version>4.7.3.0</maven.spotbugs.version>
 		<strimzi-oauth.version>0.15.0</strimzi-oauth.version>
+		<strimzi-metrics-reporter.version>0.1.0</strimzi-metrics-reporter.version>
 		<opentelemetry.version>1.34.1</opentelemetry.version>
 		<opentelemetry-alpha.version>1.34.1-alpha</opentelemetry-alpha.version>
 		<opentelemetry.instrumentation.version>1.32.0-alpha</opentelemetry.instrumentation.version>
@@ -295,6 +297,11 @@
 			<artifactId>micrometer-registry-prometheus</artifactId>
 			<version>${micrometer.version}</version>
 		</dependency>
+		<dependency>
+			<groupId>io.strimzi</groupId>
+			<artifactId>metrics-reporter</artifactId>
+			<version>${strimzi-metrics-reporter.version}</version>
+		</dependency>
 		<dependency>
 			<groupId>io.prometheus.jmx</groupId>
 			<artifactId>collector</artifactId>
@@ -305,6 +312,16 @@
 			<artifactId>prometheus-metrics-model</artifactId>
 			<version>${prometheus-client.version}</version>
 		</dependency>
+		<dependency>
+			<groupId>io.prometheus</groupId>
+			<artifactId>prometheus-metrics-instrumentation-jvm</artifactId>
+			<version>${prometheus-client.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>io.prometheus</groupId>
+			<artifactId>prometheus-metrics-exporter-httpserver</artifactId>
+			<version>${prometheus-client.version}</version>
+		</dependency>
 		<dependency>
 			<groupId>io.prometheus</groupId>
 			<artifactId>prometheus-metrics-exposition-textformats</artifactId>
@@ -421,6 +438,12 @@
 			<version>${hamcrest.version}</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.mockito</groupId>
+			<artifactId>mockito-core</artifactId>
+			<version>${mockito.version}</version>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>io.strimzi</groupId>
 			<artifactId>strimzi-test-container</artifactId>
@@ -584,6 +607,10 @@
 									<!-- OpenTelemetry - used via classpath configuration opentelemetry-exporter-sender-grpc is required at runtime to replace OKHTTP -->
 									<ignoredUnusedDeclaredDependency>io.grpc:grpc-netty-shaded:jar</ignoredUnusedDeclaredDependency>
 									<ignoredUnusedDeclaredDependency>com.google.guava:guava</ignoredUnusedDeclaredDependency>
+									<!-- Strimzi Metrics Reporter - used via classpath configuration -->
+									<ignoredUnusedDeclaredDependency>io.strimzi:metrics-reporter</ignoredUnusedDeclaredDependency>
+									<ignoredUnusedDeclaredDependency>io.prometheus:prometheus-metrics-instrumentation-jvm</ignoredUnusedDeclaredDependency>
+									<ignoredUnusedDeclaredDependency>io.prometheus:prometheus-metrics-exporter-httpserver</ignoredUnusedDeclaredDependency>
 								</ignoredUnusedDeclaredDependencies>
 						</configuration>
 					</execution>