Add integration tests for Prometheus

implementations/micrometer-registry-prometheus/build.gradle

@@ -11,6 +11,9 @@ dependencies {
     api 'io.prometheus:prometheus-metrics-tracer-common'
     implementation 'io.prometheus:prometheus-metrics-exposition-formats'
 
-    testImplementation 'io.prometheus:prometheus-metrics-tracer-common'
     testImplementation project(':micrometer-test')
+    testImplementation 'io.prometheus:prometheus-metrics-tracer-common'
+    testImplementation 'io.rest-assured:rest-assured'
+    testImplementation 'org.testcontainers:junit-jupiter'
+    testImplementation 'org.awaitility:awaitility'
 }

implementations/micrometer-registry-prometheus/src/test/java/io/micrometer/prometheusmetrics/PrometheusMeterRegistryIntegrationTest.java

@@ -0,0 +1,305 @@
+/*
+ * Copyright 2024 VMware, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.micrometer.prometheusmetrics;
+
+import com.sun.net.httpserver.HttpServer;
+import io.micrometer.common.lang.Nullable;
+import io.micrometer.core.instrument.*;
+import io.micrometer.core.instrument.Meter.Type;
+import io.micrometer.core.instrument.binder.jvm.JvmInfoMetrics;
+import io.prometheus.metrics.model.registry.PrometheusRegistry;
+import io.prometheus.metrics.tracer.common.SpanContext;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.containers.ContainerState;
+import org.testcontainers.containers.GenericContainer;
+import org.testcontainers.containers.wait.strategy.Wait;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.net.InetSocketAddress;
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
+
+import static io.restassured.RestAssured.given;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.awaitility.Awaitility.await;
+import static org.hamcrest.Matchers.*;
+import static org.testcontainers.containers.BindMode.READ_ONLY;
+
+/**
+ * Integration tests for {@link PrometheusMeterRegistry}.
+ *
+ * @author Jonatan Ivanov
+ */
+@Testcontainers
+@Tag("docker")
+class PrometheusMeterRegistryIntegrationTest {
+
+    @Container
+    static GenericContainer<?> prometheus = new GenericContainer<>(DockerImageName.parse("prom/prometheus:latest"))
+        .withCommand("--config.file=/etc/prometheus/prometheus.yml")
+        .withClasspathResourceMapping("prometheus.yml", "/etc/prometheus/prometheus.yml", READ_ONLY)
+        .waitingFor(Wait.forLogMessage(".*Server is ready to receive web requests.*", 1))
+        .withExposedPorts(9090)
+        .withAccessToHost(true);
+
+    private PrometheusMeterRegistry registry;
+
+    @Nullable
+    private HttpServer openMetricsServer;
+
+    @Nullable
+    private HttpServer prometheusTextServer;
+
+    @BeforeEach
+    void setUp() {
+        org.testcontainers.Testcontainers.exposeHostPorts(12345, 12346);
+        registry = new PrometheusMeterRegistry(PrometheusConfig.DEFAULT, new PrometheusRegistry(), Clock.SYSTEM,
+                new TestSpanContext());
+        System.out.println("Prometheus server is listening on http://localhost:" + prometheus.getFirstMappedPort());
+    }
+
+    @AfterEach
+    void tearDown() {
+        if (openMetricsServer != null) {
+            openMetricsServer.stop(0);
+            openMetricsServer = null;
+        }
+        if (prometheusTextServer != null) {
+            prometheusTextServer.stop(0);
+            prometheusTextServer = null;
+        }
+    }
+
+    @Test
+    void prometheusShouldScrapeOpenMetricsResult() throws IOException {
+        this.openMetricsServer = startHttpServer(12345);
+        verifyBuildInfo();
+        recordMetrics();
+        verifyOpenMetricsScrapeResult();
+        await().atMost(Duration.ofSeconds(10)).untilAsserted(() -> verifyIfPrometheusHasAnyMetrics("test-app-om"));
+        verifyPrometheusHasAllMetrics("test-app-om");
+    }
+
+    @Test
+    void prometheusShouldScrapePrometheusTextResult() throws IOException {
+        this.prometheusTextServer = startHttpServer(12346);
+        verifyBuildInfo();
+        recordMetrics();
+        verifyPrometheusTextScrapeResult();
+
+        await().atMost(Duration.ofSeconds(10)).untilAsserted(() -> verifyIfPrometheusHasAnyMetrics("test-app-pt"));
+        verifyPrometheusHasAllMetrics("test-app-pt");
+    }
+
+    private void recordMetrics() {
+        new JvmInfoMetrics().bindTo(registry);
+        registry.counter("test.counter").increment();
+        registry.gauge("test.gauge", prometheus.getFirstMappedPort());
+        DistributionSummary.builder("test.ds")
+            .publishPercentileHistogram()
+            .serviceLevelObjectives(10, 100)
+            .publishPercentiles(0.99)
+            .register(registry)
+            .record(42);
+        Timer.builder("test.timer")
+            .publishPercentileHistogram()
+            .serviceLevelObjectives(Duration.ofMillis(10), Duration.ofMillis(100))
+            .publishPercentiles(0.99)
+            .register(registry)
+            .record(200, MILLISECONDS);
+        LongTaskTimer.builder("test.ltt").publishPercentileHistogram().register(registry).start();
+        // @formatter:off
+        FunctionTimer.builder(
+            "test.ft",
+                prometheus,
+                GenericContainer::getStartupAttempts,
+                ContainerState::getFirstMappedPort,
+                SECONDS
+            ).register(registry);
+        // @formatter:on
+        FunctionCounter.builder("test.fc", prometheus, ContainerState::getFirstMappedPort).register(registry);
+        TimeGauge.builder("test.tg", () -> 42, MILLISECONDS).register(registry);
+
+        List<Measurement> measurements = new ArrayList<>();
+        for (int i = 0; i < Statistic.values().length; i++) {
+            final int value = i;
+            measurements.add(new Measurement(() -> value + 10, Statistic.values()[i]));
+        }
+        Meter.builder("test.custom", Type.OTHER, measurements).register(registry);
+    }
+
+    private void verifyBuildInfo() {
+        // @formatter:off
+        given()
+            .port(prometheus.getFirstMappedPort())
+        .when()
+            .get("/api/v1/status/buildinfo")
+        .then()
+            .body("status", equalTo("success"))
+            .body("data.version", startsWith("2."))
+            .statusCode(200);
+        // @formatter:on
+    }
+
+    private void verifyOpenMetricsScrapeResult() {
+        // @formatter:off
+        given()
+            .port(12345)
+        .when()
+            .header("Accept", "application/openmetrics-text")
+            .get("/metrics")
+        .then()
+            .statusCode(200)
+            .header("Content-Type", "application/openmetrics-text; version=1.0.0; charset=utf-8")
+            .body(endsWith("# EOF\n")) // indicates OpenMetrics body
+            // exemplars should present
+            .body(containsString("test_counter_total 1.0 # {span_id=\"321\",trace_id=\"123\"} 1.0 "))
+            .body(containsString("test_ds_bucket{le=\"46.0\"} 1 # {span_id=\"321\",trace_id=\"123\"} 42.0"))
+            .body(containsString("test_ds_count 1 # {span_id=\"321\",trace_id=\"123\"} 42.0"))
+            .body(containsString("test_timer_seconds_bucket{le=\"0.20132659\"} 1 # {span_id=\"321\",trace_id=\"123\"} 0.2"))
+            .body(containsString("test_timer_seconds_count 1 # {span_id=\"321\",trace_id=\"123\"} 0.2"));
+        // @formatter:on
+    }
+
+    private void verifyPrometheusTextScrapeResult() {
+        // @formatter:off
+        given()
+            .port(12346)
+        .when()
+            .header("Accept", "*/*")
+            .get("/metrics")
+        .then()
+            .statusCode(200)
+            .header("Content-Type", "text/plain; version=0.0.4; charset=utf-8")
+            .body(not((contains("# EOF"))));
+        // @formatter:on
+    }
+
+    private void verifyIfPrometheusHasAnyMetrics(String jobName) {
+        // @formatter:off
+        given()
+            .port(prometheus.getFirstMappedPort())
+        .when()
+            .queryParam("match[]", "{job=\"" + jobName + "\"}")
+            .get("/federate")
+        .then()
+            .statusCode(200)
+            .body(containsString("test_counter_total"));
+        // @formatter:on
+    }
+
+    private void verifyPrometheusHasAllMetrics(String jobName) {
+        // @formatter:off
+        given()
+            .port(prometheus.getFirstMappedPort())
+        .when()
+            .queryParam("match[]", "{job=\"" + jobName + "\"}")
+            .get("/federate")
+        .then()
+            .statusCode(200)
+            .body(
+                containsString("jvm_info"),
+                containsString("test_counter_total"),
+                containsString("test_gauge"),
+
+                containsString("test_ds_bucket"),
+                containsString("test_ds_count"),
+                containsString("test_ds_sum"),
+                containsString("test_ds_max"),
+
+                containsString("test_timer_seconds_bucket"),
+                containsString("test_timer_seconds_count"),
+                containsString("test_timer_seconds_sum"),
+                containsString("test_timer_seconds_max"),
+
+                containsString("test_ltt_seconds_bucket"),
+                containsString("test_ltt_seconds_gcount"),
+                containsString("test_ltt_seconds_gsum"),
+                containsString("test_ltt_seconds_max"),
+
+                containsString("test_ft_seconds_count"),
+                containsString("test_ft_seconds_sum"),
+                containsString("test_fc_total"),
+                containsString("test_tg_seconds"),
+
+                containsString("test_custom_total"),
+                containsString("test_custom_active_count"),
+                containsString("test_custom_duration_sum"),
+                containsString("test_custom_max"),
+                containsString("test_custom_sum_total"),
+                containsString("test_custom_value")
+            );
+        // @formatter:on
+    }
+
+    private HttpServer startHttpServer(int port) throws IOException {
+        HttpServer server = HttpServer.create(new InetSocketAddress(port), 0);
+        server.createContext("/metrics", httpExchange -> {
+            String acceptHeader = httpExchange.getRequestHeaders().getFirst("Accept");
+            String contentType;
+            if (acceptHeader.startsWith("application/openmetrics-text")) {
+                contentType = "application/openmetrics-text; version=1.0.0; charset=utf-8";
+            }
+            else {
+                contentType = "text/plain; version=0.0.4; charset=utf-8";
+            }
+            String response = registry.scrape(acceptHeader);
+
+            httpExchange.getResponseHeaders().add("Content-Type", contentType);
+            httpExchange.sendResponseHeaders(200, response.getBytes().length);
+            try (OutputStream outputStream = httpExchange.getResponseBody()) {
+                outputStream.write(response.getBytes());
+            }
+        });
+        new Thread(server::start).start();
+
+        return server;
+    }
+
+    static class TestSpanContext implements SpanContext {
+
+        @Override
+        public String getCurrentTraceId() {
+            return "123";
+        }
+
+        @Override
+        public String getCurrentSpanId() {
+            return "321";
+        }
+
+        @Override
+        public boolean isCurrentSpanSampled() {
+            return true;
+        }
+
+        @Override
+        public void markCurrentSpanAsExemplar() {
+            // noop
+        }
+
+    }
+
+}

implementations/micrometer-registry-prometheus/src/test/resources/prometheus.yml

@@ -0,0 +1,27 @@
+#
+# Copyright 2024 VMware, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+global:
+  scrape_interval: 5s
+  evaluation_interval: 5s
+
+scrape_configs:
+  - job_name: 'test-app-om' # test app that produces OpenMetrics output
+    static_configs:
+      - targets: [ 'host.testcontainers.internal:12345']
+  - job_name: 'test-app-pt'  # test app that produces Prometheus text output
+    static_configs:
+      - targets: [ 'host.testcontainers.internal:12346' ]