Migrate to actively-maintained Prometheus client

cwms-data-api/src/main/java/cwms/cda/CdaMetricsContextListener.java

@@ -5,16 +5,18 @@
 import com.codahale.metrics.MetricRegistry;
 import com.codahale.metrics.servlets.MetricsServlet;
 
-import io.prometheus.client.CollectorRegistry;
-import io.prometheus.client.dropwizard.DropwizardExports;
+import io.prometheus.metrics.instrumentation.dropwizard.DropwizardExports;
+import io.prometheus.metrics.model.registry.PrometheusRegistry;
 
 @WebListener
 public class CdaMetricsContextListener extends MetricsServlet.ContextListener {
 
     public static final MetricRegistry METRIC_REGISTRY = new MetricRegistry();
 
     static {
-        CollectorRegistry.defaultRegistry.register(new DropwizardExports(METRIC_REGISTRY));
+        DropwizardExports.builder()
+                .dropwizardRegistry(METRIC_REGISTRY)
+                .register(PrometheusRegistry.defaultRegistry);
     }
 
     @Override

cwms-data-api/src/main/webapp/WEB-INF/web.xml

@@ -11,7 +11,7 @@
 
     <servlet>
         <servlet-name>metrics-prometheus</servlet-name>
-        <servlet-class>io.prometheus.client.exporter.MetricsServlet</servlet-class>
+        <servlet-class>io.prometheus.metrics.exporter.servlet.javax.PrometheusMetricsServlet</servlet-class>
     </servlet>
     <servlet-mapping>
         <servlet-name>metrics-prometheus</servlet-name>

cwms-data-api/src/test/java/cwms/cda/CdaMetricsContextListenerTest.java

@@ -0,0 +1,34 @@
+package cwms.cda;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import com.codahale.metrics.MetricRegistry;
+import io.prometheus.metrics.instrumentation.dropwizard.DropwizardExports;
+import io.prometheus.metrics.model.registry.PrometheusRegistry;
+import io.prometheus.metrics.model.snapshots.CounterSnapshot;
+import io.prometheus.metrics.model.snapshots.MetricSnapshots;
+import org.junit.jupiter.api.Test;
+
+class CdaMetricsContextListenerTest {
+
+    @Test
+    void webXmlServletClassIsOnClasspath() {
+        assertDoesNotThrow(() -> Class.forName(
+                "io.prometheus.metrics.exporter.servlet.javax.PrometheusMetricsServlet"));
+    }
+
+    @Test
+    void codahaleCounterIsExportedToPrometheusRegistry() {
+        MetricRegistry codaHale = new MetricRegistry();
+        PrometheusRegistry prom = new PrometheusRegistry();
+        DropwizardExports.builder().dropwizardRegistry(codaHale).register(prom);
+
+        codaHale.counter("cda_test_counter").inc(7);
+
+        MetricSnapshots snapshots = prom.scrape();
+        CounterSnapshot snapshot = (CounterSnapshot) snapshots.iterator().next();
+        assertEquals("cda_test_counter", snapshot.getMetadata().getPrometheusName());
+        assertEquals(7.0, snapshot.getDataPoints().get(0).getValue());
+    }
+}

gradle/libs.versions.toml

@@ -16,7 +16,7 @@ swagger-core = "2.2.23"
 jackson = "2.17.1"
 geojson-jackson = "1.14"
 dropwizard = "4.2.12"
-dropwizard_prometheus = "0.15.0"
+prometheus_client = "1.6.1"
 owasp = "20220608.1"
 java-ee = "8.0.1"
 cwms-tomcat-auth = "1.1.0"
@@ -73,8 +73,8 @@ javalin-openapi = { module = "io.javalin:javalin-openapi", version.ref = "javali
 swagger-core = { module = "io.swagger.core.v3:swagger-core", version.ref = "swagger-core" }
 metrics-core = { module = "io.dropwizard.metrics:metrics-core", version.ref = "dropwizard" }
 metrics-servlets = { module = "io.dropwizard.metrics:metrics-servlets", version.ref = "dropwizard" }
-metrics-prometheus-client = { module = "io.prometheus:simpleclient_dropwizard", version.ref = "dropwizard_prometheus" }
-metrics-prometheus-servlets = { module = "io.prometheus:simpleclient_servlet", version.ref = "dropwizard_prometheus" }
+metrics-prometheus-client = { module = "io.prometheus:prometheus-metrics-instrumentation-dropwizard", version.ref = "prometheus_client" }
+metrics-prometheus-servlets = { module = "io.prometheus:prometheus-metrics-exporter-servlet-javax", version.ref = "prometheus_client" }
 password4j = { module = "com.password4j:password4j", version = "1.8.4" }