Add API for metrics based on Micrometer (#1576)

scm-webapp/src/main/java/sonia/scm/api/v2/resources/MetricsIndexEnricher.java

@@ -0,0 +1,72 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.api.v2.resources;
+
+import org.apache.shiro.SecurityUtils;
+import sonia.scm.metrics.MonitoringSystem;
+import sonia.scm.plugin.Extension;
+
+import javax.inject.Inject;
+import javax.inject.Provider;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+@Extension
+@Enrich(Index.class)
+public class MetricsIndexEnricher implements HalEnricher {
+
+  private final Provider<ResourceLinks> resourceLinks;
+  private final List<String> scrapeTargets;
+
+  @Inject
+  public MetricsIndexEnricher(Provider<ResourceLinks> resourceLinks, Set<MonitoringSystem> monitoringSystems) {
+    this.resourceLinks = resourceLinks;
+    this.scrapeTargets = scrapeTargets(monitoringSystems);
+  }
+
+  private List<String> scrapeTargets(Set<MonitoringSystem> monitoringSystems) {
+    return monitoringSystems.stream()
+      .filter(sys -> sys.getScrapeTarget().isPresent())
+      .map(MonitoringSystem::getName)
+      .collect(Collectors.toList());
+  }
+
+  @Override
+  public void enrich(HalEnricherContext context, HalAppender appender) {
+    if (!isPermitted() || scrapeTargets.isEmpty()) {
+      return;
+    }
+    HalAppender.LinkArrayBuilder links = appender.linkArrayBuilder("metrics");
+    for (String type : scrapeTargets) {
+      links.append(type, resourceLinks.get().metrics().forType(type));
+    }
+    links.build();
+  }
+
+  private boolean isPermitted() {
+    return SecurityUtils.getSubject().isPermitted("metrics:read");
+  }
+}

scm-webapp/src/main/java/sonia/scm/api/v2/resources/MetricsResource.java

@@ -0,0 +1,101 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.api.v2.resources;
+
+import io.swagger.v3.oas.annotations.OpenAPIDefinition;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import org.apache.shiro.SecurityUtils;
+import sonia.scm.NotFoundException;
+import sonia.scm.metrics.MonitoringSystem;
+import sonia.scm.metrics.ScrapeTarget;
+import sonia.scm.web.VndMediaType;
+
+import javax.inject.Inject;
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.PathParam;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.core.StreamingOutput;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
+import static sonia.scm.ContextEntry.ContextBuilder.entity;
+
+/**
+ * Endpoint for pull based monitoring systems, which scrape for metrics.
+ * @since 2.15.0
+ */
+@OpenAPIDefinition(tags = {
+  @Tag(name = "Metrics", description = "Scrape targets for monitoring systems")
+})
+@Path("v2/metrics")
+public class MetricsResource {
+
+  private final Map<String, MonitoringSystem> providers = new HashMap<>();
+
+  @Inject
+  public MetricsResource(Set<MonitoringSystem> monitoringSystems) {
+    for (MonitoringSystem system : monitoringSystems) {
+      providers.put(system.getName(), system);
+    }
+  }
+
+  @GET
+  @Path("{name}")
+  @Operation(summary = "Scrape target", description = "Scrape target for a monitoring system", tags = "Metrics")
+  @ApiResponse(
+    responseCode = "200",
+    description = "success"
+  )
+  @ApiResponse(responseCode = "401", description = "not authenticated / invalid credentials")
+  @ApiResponse(responseCode = "404", description = "unknown monitoring system or system without scrape target")
+  @ApiResponse(
+    responseCode = "500",
+    description = "internal server error",
+    content = @Content(
+      mediaType = VndMediaType.ERROR_TYPE,
+      schema = @Schema(implementation = ErrorDto.class)
+    ))
+  public Response metrics(@PathParam("name") String name) {
+    SecurityUtils.getSubject().checkPermission("metrics:read");
+
+    MonitoringSystem system = providers.get(name);
+    if (system == null) {
+      throw new NotFoundException(MonitoringSystem.class, name);
+    }
+
+    ScrapeTarget scrapeTarget = system.getScrapeTarget()
+      .orElseThrow(() -> NotFoundException.notFound(entity(ScrapeTarget.class, name).in(MonitoringSystem.class, name)));
+
+    StreamingOutput output = scrapeTarget::write;
+    return Response.ok(output, scrapeTarget.getContentType()).build();
+  }
+
+}

scm-webapp/src/main/java/sonia/scm/api/v2/resources/ResourceLinks.java

@@ -1085,4 +1085,21 @@ class ResourceLinks {
       return permissionLinkBuilder.method("getNamespaceResource").parameters(namespace).method("permissions").parameters().method(methodName).parameters(permissionName).href();
     }
   }
+
+  public MetricsLinks metrics() {
+    return new MetricsLinks(new LinkBuilder(scmPathInfoStore.get(), MetricsResource.class));
+  }
+
+  public static class MetricsLinks {
+
+    private final LinkBuilder metricsLinkBuilder;
+
+    private MetricsLinks(LinkBuilder metricsLinkBuilder) {
+      this.metricsLinkBuilder = metricsLinkBuilder;
+    }
+
+    public String forType(String type) {
+      return metricsLinkBuilder.method("metrics").parameters(type).href();
+    }
+  }
 }

scm-webapp/src/main/java/sonia/scm/lifecycle/modules/ScmServletModule.java

@@ -30,6 +30,7 @@ import com.google.inject.multibindings.Multibinder;
 import com.google.inject.servlet.RequestScoped;
 import com.google.inject.servlet.ServletModule;
 import com.google.inject.throwingproviders.ThrowingProviderBinder;
+import io.micrometer.core.instrument.MeterRegistry;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import sonia.scm.Default;
@@ -54,6 +55,7 @@ import sonia.scm.group.GroupDisplayManager;
 import sonia.scm.group.GroupManager;
 import sonia.scm.group.GroupManagerProvider;
 import sonia.scm.group.xml.XmlGroupDAO;
+import sonia.scm.metrics.MeterRegistryProvider;
 import sonia.scm.migration.MigrationDAO;
 import sonia.scm.net.SSLContextProvider;
 import sonia.scm.net.ahc.AdvancedHttpClient;
@@ -170,6 +172,9 @@ class ScmServletModule extends ServletModule {
     // bind extensions
     pluginLoader.getExtensionProcessor().processAutoBindExtensions(binder());
 
+    // bind metrics
+    bind(MeterRegistry.class).toProvider(MeterRegistryProvider.class).asEagerSingleton();
+
     // bind security stuff
     bind(LoginAttemptHandler.class).to(ConfigurableLoginAttemptHandler.class);
     bind(AuthorizationChangedEventProducer.class);

scm-webapp/src/main/java/sonia/scm/metrics/MeterRegistryProvider.java

@@ -0,0 +1,82 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.metrics;
+
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.instrument.binder.jvm.ClassLoaderMetrics;
+import io.micrometer.core.instrument.binder.jvm.JvmGcMetrics;
+import io.micrometer.core.instrument.binder.jvm.JvmMemoryMetrics;
+import io.micrometer.core.instrument.binder.jvm.JvmThreadMetrics;
+import io.micrometer.core.instrument.binder.system.ProcessorMetrics;
+import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
+
+import javax.inject.Inject;
+import javax.inject.Provider;
+import javax.inject.Singleton;
+import java.util.Set;
+
+@Singleton
+public class MeterRegistryProvider implements Provider<MeterRegistry> {
+
+  private final Set<MonitoringSystem> providerSet;
+
+  @Inject
+  public MeterRegistryProvider(Set<MonitoringSystem> providerSet) {
+    this.providerSet = providerSet;
+  }
+
+  @Override
+  public MeterRegistry get() {
+    MeterRegistry registry = createRegistry();
+    if (!providerSet.isEmpty()) {
+      bindCommonMetrics(registry);
+    }
+    return registry;
+  }
+
+  private MeterRegistry createRegistry() {
+    if (providerSet.size() == 1) {
+      return providerSet.iterator().next().getRegistry();
+    }
+    return createCompositeRegistry();
+  }
+
+  private CompositeMeterRegistry createCompositeRegistry() {
+    CompositeMeterRegistry registry = new CompositeMeterRegistry();
+    for (MonitoringSystem provider : providerSet) {
+      registry.add(provider.getRegistry());
+    }
+    return registry;
+  }
+
+  @SuppressWarnings("java:S2095") // we can't close JvmGcMetrics, but it should be ok
+  private void bindCommonMetrics(MeterRegistry registry) {
+    new ClassLoaderMetrics().bindTo(registry);
+    new JvmMemoryMetrics().bindTo(registry);
+    new JvmGcMetrics().bindTo(registry);
+    new ProcessorMetrics().bindTo(registry);
+    new JvmThreadMetrics().bindTo(registry);
+  }
+}