make protobuf optional

zeitlinger · zeitlinger · commit b4f5707fc5d3 · 2024-11-08T11:16:12.000+01:00
Signed-off-by: Gregor Zeitlinger &lt;gregor.zeitlinger@grafana.com&gt;
diff --git a/pom.xml b/pom.xml
@@ -91,6 +91,14 @@
     </dependencyManagement>
 
     <dependencies>
+        <dependency>
+            <groupId>com.google.code.findbugs</groupId>
+            <artifactId>jsr305</artifactId>
+            <version>3.0.2</version>
+            <scope>compile</scope>
+        </dependency>
+
+        <!-- test dependencies -->
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>
diff --git a/prometheus-metrics-exporter-common/pom.xml b/prometheus-metrics-exporter-common/pom.xml
@@ -26,10 +26,16 @@
             <artifactId>prometheus-metrics-model</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.prometheus</groupId>
+            <artifactId>prometheus-writer-textformat</artifactId>
+            <version>${project.version}</version>
+        </dependency>
         <dependency>
             <groupId>io.prometheus</groupId>
             <artifactId>prometheus-metrics-exposition-formats</artifactId>
             <version>${project.version}</version>
+            <scope>runtime</scope>
         </dependency>
     </dependencies>
 
diff --git a/prometheus-metrics-exporter-common/src/main/java/io/prometheus/metrics/exporter/common/PrometheusScrapeHandler.java b/prometheus-metrics-exporter-common/src/main/java/io/prometheus/metrics/exporter/common/PrometheusScrapeHandler.java
@@ -11,8 +11,10 @@
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Enumeration;
+import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Predicate;
 import java.util.zip.GZIPOutputStream;
@@ -23,7 +25,8 @@ public class PrometheusScrapeHandler {
   private final PrometheusRegistry registry;
   private final ExpositionFormats expositionFormats;
   private final Predicate<String> nameFilter;
-  private AtomicInteger lastResponseSize = new AtomicInteger(2 << 9); //  0.5 MB
+  private final AtomicInteger lastResponseSize = new AtomicInteger(2 << 9); //  0.5 MB
+  private final List<String> supportedFormats;
 
   public PrometheusScrapeHandler() {
     this(PrometheusProperties.get(), PrometheusRegistry.defaultRegistry);
@@ -41,6 +44,10 @@ public PrometheusScrapeHandler(PrometheusProperties config, PrometheusRegistry r
     this.expositionFormats = ExpositionFormats.init(config.getExporterProperties());
     this.registry = registry;
     this.nameFilter = makeNameFilter(config.getExporterFilterProperties());
+    supportedFormats = new ArrayList<>(Arrays.asList("openmetrics", "text"));
+    if (expositionFormats.getPrometheusProtobufWriter() != null) {
+      supportedFormats.add("prometheus-protobuf");
+    }
   }
 
   public void handleRequest(PrometheusHttpExchange exchange) throws IOException {
@@ -137,9 +144,7 @@ private boolean writeDebugResponse(MetricSnapshots snapshots, PrometheusHttpExch
       return false;
     } else {
       response.setHeader("Content-Type", "text/plain; charset=utf-8");
-      boolean supportedFormat =
-          Arrays.asList("openmetrics", "text", "prometheus-protobuf").contains(debugParam);
-      int responseStatus = supportedFormat ? 200 : 500;
+      int responseStatus = supportedFormats.contains(debugParam) ? 200 : 500;
       OutputStream body = response.sendHeadersAndGetBody(responseStatus, 0);
       switch (debugParam) {
         case "openmetrics":
diff --git a/prometheus-metrics-exporter-pushgateway/src/main/java/io/prometheus/metrics/exporter/pushgateway/PushGateway.java b/prometheus-metrics-exporter-pushgateway/src/main/java/io/prometheus/metrics/exporter/pushgateway/PushGateway.java
@@ -5,7 +5,8 @@
 import io.prometheus.metrics.config.ExporterPushgatewayProperties;
 import io.prometheus.metrics.config.PrometheusProperties;
 import io.prometheus.metrics.config.PrometheusPropertiesException;
-import io.prometheus.metrics.expositionformats.PrometheusProtobufWriter;
+import io.prometheus.metrics.expositionformats.ExpositionFormatWriter;
+import io.prometheus.metrics.expositionformats.ExpositionFormats;
 import io.prometheus.metrics.expositionformats.PrometheusTextFormatWriter;
 import io.prometheus.metrics.model.registry.Collector;
 import io.prometheus.metrics.model.registry.MultiCollector;
@@ -64,7 +65,7 @@ public class PushGateway {
   private static final int MILLISECONDS_PER_SECOND = 1000;
 
   private final URL url;
-  private final Format format;
+  private final ExpositionFormatWriter writer;
   private final Map<String, String> requestHeaders;
   private final PrometheusRegistry registry;
   private final HttpConnectionFactory connectionFactory;
@@ -76,10 +77,19 @@ private PushGateway(
       HttpConnectionFactory connectionFactory,
       Map<String, String> requestHeaders) {
     this.registry = registry;
-    this.format = format;
     this.url = url;
     this.requestHeaders = Collections.unmodifiableMap(new HashMap<>(requestHeaders));
     this.connectionFactory = connectionFactory;
+    writer = getWriter(format);
+  }
+
+  private ExpositionFormatWriter getWriter(Format format) {
+    if (format == Format.PROMETHEUS_TEXT) {
+      return new PrometheusTextFormatWriter(false);
+    } else {
+      // use reflection to avoid a compile-time dependency on the expositionformats module
+      return ExpositionFormats.createProtobufWriter();
+    }
   }
 
   /**
@@ -160,11 +170,7 @@ private void doRequest(PrometheusRegistry registry, String method) throws IOExce
     try {
       HttpURLConnection connection = connectionFactory.create(url);
       requestHeaders.forEach(connection::setRequestProperty);
-      if (format == Format.PROMETHEUS_TEXT) {
-        connection.setRequestProperty("Content-Type", PrometheusTextFormatWriter.CONTENT_TYPE);
-      } else {
-        connection.setRequestProperty("Content-Type", PrometheusProtobufWriter.CONTENT_TYPE);
-      }
+      connection.setRequestProperty("Content-Type", writer.getContentType());
       if (!method.equals("DELETE")) {
         connection.setDoOutput(true);
       }
@@ -177,11 +183,7 @@ private void doRequest(PrometheusRegistry registry, String method) throws IOExce
       try {
         if (!method.equals("DELETE")) {
           OutputStream outputStream = connection.getOutputStream();
-          if (format == Format.PROMETHEUS_TEXT) {
-            new PrometheusTextFormatWriter(false).write(outputStream, registry.scrape());
-          } else {
-            new PrometheusProtobufWriter().write(outputStream, registry.scrape());
-          }
+          writer.write(outputStream, registry.scrape());
           outputStream.flush();
           outputStream.close();
         }
diff --git a/prometheus-metrics-exposition-formats/src/main/java/io/prometheus/metrics/expositionformats/PrometheusProtobufWriter.java b/prometheus-metrics-exposition-formats/src/main/java/io/prometheus/metrics/expositionformats/PrometheusProtobufWriter.java
@@ -50,10 +50,11 @@ public String getContentType() {
     return CONTENT_TYPE;
   }
 
+  @Override
   public String toDebugString(MetricSnapshots metricSnapshots) {
     StringBuilder stringBuilder = new StringBuilder();
     for (MetricSnapshot snapshot : metricSnapshots) {
-      if (snapshot.getDataPoints().size() > 0) {
+      if (!snapshot.getDataPoints().isEmpty()) {
         stringBuilder.append(TextFormat.printer().printToString(convert(snapshot)));
       }
     }
@@ -63,7 +64,7 @@ public String toDebugString(MetricSnapshots metricSnapshots) {
   @Override
   public void write(OutputStream out, MetricSnapshots metricSnapshots) throws IOException {
     for (MetricSnapshot snapshot : metricSnapshots) {
-      if (snapshot.getDataPoints().size() > 0) {
+      if (!snapshot.getDataPoints().isEmpty()) {
         convert(snapshot).writeDelimitedTo(out);
       }
     }
diff --git a/prometheus-writer-textformat/src/main/java/io/prometheus/metrics/expositionformats/ExpositionFormatWriter.java b/prometheus-writer-textformat/src/main/java/io/prometheus/metrics/expositionformats/ExpositionFormatWriter.java
@@ -1,6 +1,7 @@
 package io.prometheus.metrics.expositionformats;
 
 import io.prometheus.metrics.model.snapshots.MetricSnapshots;
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 
@@ -10,5 +11,15 @@ public interface ExpositionFormatWriter {
   /** Text formats use UTF-8 encoding. */
   void write(OutputStream out, MetricSnapshots metricSnapshots) throws IOException;
 
+  default String toDebugString(MetricSnapshots metricSnapshots) {
+    ByteArrayOutputStream out = new ByteArrayOutputStream();
+    try {
+      write(out, metricSnapshots);
+      return out.toString("UTF-8");
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
   String getContentType();
 }
diff --git a/prometheus-writer-textformat/src/main/java/io/prometheus/metrics/expositionformats/ExpositionFormats.java b/prometheus-writer-textformat/src/main/java/io/prometheus/metrics/expositionformats/ExpositionFormats.java
@@ -2,17 +2,18 @@
 
 import io.prometheus.metrics.config.ExporterProperties;
 import io.prometheus.metrics.config.PrometheusProperties;
+import javax.annotation.Nullable;
 
 public class ExpositionFormats {
 
-  private final PrometheusProtobufWriter prometheusProtobufWriter;
-  private final PrometheusTextFormatWriter prometheusTextFormatWriter;
-  private final OpenMetricsTextFormatWriter openMetricsTextFormatWriter;
+  @Nullable private final ExpositionFormatWriter prometheusProtobufWriter;
+  private final ExpositionFormatWriter prometheusTextFormatWriter;
+  private final ExpositionFormatWriter openMetricsTextFormatWriter;
 
   private ExpositionFormats(
-      PrometheusProtobufWriter prometheusProtobufWriter,
-      PrometheusTextFormatWriter prometheusTextFormatWriter,
-      OpenMetricsTextFormatWriter openMetricsTextFormatWriter) {
+      ExpositionFormatWriter prometheusProtobufWriter,
+      ExpositionFormatWriter prometheusTextFormatWriter,
+      ExpositionFormatWriter openMetricsTextFormatWriter) {
     this.prometheusProtobufWriter = prometheusProtobufWriter;
     this.prometheusTextFormatWriter = prometheusTextFormatWriter;
     this.openMetricsTextFormatWriter = openMetricsTextFormatWriter;
@@ -24,12 +25,25 @@ public static ExpositionFormats init() {
 
   public static ExpositionFormats init(ExporterProperties properties) {
     return new ExpositionFormats(
-        new PrometheusProtobufWriter(),
+        createProtobufWriter(),
         new PrometheusTextFormatWriter(properties.getIncludeCreatedTimestamps()),
         new OpenMetricsTextFormatWriter(
             properties.getIncludeCreatedTimestamps(), properties.getExemplarsOnAllMetricTypes()));
   }
 
+  @Nullable
+  public static ExpositionFormatWriter createProtobufWriter() {
+    try {
+      return Class.forName("io.prometheus.metrics.expositionformats.PrometheusProtobufWriter")
+          .asSubclass(ExpositionFormatWriter.class)
+          .getDeclaredConstructor()
+          .newInstance();
+    } catch (Exception e) {
+      // not in classpath
+      return null;
+    }
+  }
+
   public ExpositionFormatWriter findWriter(String acceptHeader) {
     if (prometheusProtobufWriter.accepts(acceptHeader)) {
       return prometheusProtobufWriter;
@@ -40,15 +54,15 @@ public ExpositionFormatWriter findWriter(String acceptHeader) {
     return prometheusTextFormatWriter;
   }
 
-  public PrometheusProtobufWriter getPrometheusProtobufWriter() {
+  public ExpositionFormatWriter getPrometheusProtobufWriter() {
     return prometheusProtobufWriter;
   }
 
-  public PrometheusTextFormatWriter getPrometheusTextFormatWriter() {
+  public ExpositionFormatWriter getPrometheusTextFormatWriter() {
     return prometheusTextFormatWriter;
   }
 
-  public OpenMetricsTextFormatWriter getOpenMetricsTextFormatWriter() {
+  public ExpositionFormatWriter getOpenMetricsTextFormatWriter() {
     return openMetricsTextFormatWriter;
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -50,10 +50,11 @@ public String getContentType() {`
`50`	`50`	`return CONTENT_TYPE;`
`51`	`51`	`}`
`52`	`52`
	`53`	`+ @Override`
`53`	`54`	`public String toDebugString(MetricSnapshots metricSnapshots) {`
`54`	`55`	`StringBuilder stringBuilder = new StringBuilder();`
`55`	`56`	`for (MetricSnapshot snapshot : metricSnapshots) {`
`56`		`- if (snapshot.getDataPoints().size() > 0) {`
	`57`	`+ if (!snapshot.getDataPoints().isEmpty()) {`
`57`	`58`	`stringBuilder.append(TextFormat.printer().printToString(convert(snapshot)));`
`58`	`59`	`}`
`59`	`60`	`}`
`@@ -63,7 +64,7 @@ public String toDebugString(MetricSnapshots metricSnapshots) {`
`63`	`64`	`@Override`
`64`	`65`	`public void write(OutputStream out, MetricSnapshots metricSnapshots) throws IOException {`
`65`	`66`	`for (MetricSnapshot snapshot : metricSnapshots) {`
`66`		`- if (snapshot.getDataPoints().size() > 0) {`
	`67`	`+ if (!snapshot.getDataPoints().isEmpty()) {`
`67`	`68`	`convert(snapshot).writeDelimitedTo(out);`
`68`	`69`	`}`
`69`	`70`	`}`