Apache HTTP client instrumentation with Observation

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/httpcomponents/ApacheHttpClientContext.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2022 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.core.instrument.binder.httpcomponents;
+
+import io.micrometer.observation.transport.RequestReplySenderContext;
+import org.apache.http.HttpRequest;
+import org.apache.http.HttpResponse;
+import org.apache.http.protocol.HttpContext;
+
+import java.util.function.Function;
+
+/**
+ * {@link io.micrometer.observation.Observation.Context} for use with Apache HTTP client
+ * {@link io.micrometer.observation.Observation} instrumentation.
+ *
+ * @since 1.10.0
+ */
+public class ApacheHttpClientContext extends RequestReplySenderContext<HttpRequest, HttpResponse> {
+
+    private final HttpContext apacheHttpContext;
+
+    private final Function<HttpRequest, String> uriMapper;
+
+    private final boolean exportTagsForRoute;
+
+    public ApacheHttpClientContext(HttpRequest request, HttpContext apacheHttpContext,
+            Function<HttpRequest, String> uriMapper, boolean exportTagsForRoute) {
+        super((httpRequest, key, value) -> {
+            if (httpRequest != null) {
+                httpRequest.addHeader(key, value);
+            }
+        });
+        this.uriMapper = uriMapper;
+        this.exportTagsForRoute = exportTagsForRoute;
+        setCarrier(request);
+        this.apacheHttpContext = apacheHttpContext;
+    }
+
+    public HttpContext getApacheHttpContext() {
+        return apacheHttpContext;
+    }
+
+    public Function<HttpRequest, String> getUriMapper() {
+        return uriMapper;
+    }
+
+    public boolean shouldExportTagsForRoute() {
+        return exportTagsForRoute;
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/httpcomponents/ApacheHttpClientDocumentedObservation.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2017 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.core.instrument.binder.httpcomponents;
+
+import io.micrometer.common.docs.KeyName;
+import io.micrometer.observation.Observation;
+import io.micrometer.observation.docs.DocumentedObservation;
+
+/**
+ * {@link DocumentedObservation} for Apache HTTP client instrumentation.
+ * @since 1.10.0
+ * @see MicrometerHttpRequestExecutor
+ */
+public enum ApacheHttpClientDocumentedObservation implements DocumentedObservation {
+
+    DEFAULT {
+        @Override
+        public Class<? extends Observation.ObservationConvention<? extends Observation.Context>> getDefaultConvention() {
+            return DefaultApacheHttpClientObservationConvention.class;
+        }
+
+        @Override
+        public KeyName[] getLowCardinalityKeyNames() {
+            return ApacheHttpClientTags.values();
+        }
+    };
+
+    enum ApacheHttpClientTags implements KeyName {
+
+        STATUS {
+            @Override
+            public String asString() {
+                return "status";
+            }
+        },
+        METHOD {
+            @Override
+            public String asString() {
+                return "method";
+            }
+        },
+        URI {
+            @Override
+            public String asString() {
+                return "uri";
+            }
+        },
+        TARGET_SCHEME {
+            @Override
+            public String asString() {
+                return "target.scheme";
+            }
+        },
+        TARGET_HOST {
+            @Override
+            public String asString() {
+                return "target.host";
+            }
+        },
+        TARGET_PORT {
+            @Override
+            public String asString() {
+                return "target.port";
+            }
+        }
+
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/httpcomponents/ApacheHttpClientObservationConvention.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2022 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.core.instrument.binder.httpcomponents;
+
+import io.micrometer.observation.Observation;
+import io.micrometer.observation.Observation.ObservationConvention;
+
+/**
+ * {@link ObservationConvention} for Apache HTTP client instrumentation.
+ *
+ * @since 1.10.0
+ * @see DefaultApacheHttpClientObservationConvention
+ */
+public interface ApacheHttpClientObservationConvention extends ObservationConvention<ApacheHttpClientContext> {
+
+    @Override
+    default boolean supportsContext(Observation.Context context) {
+        return context instanceof ApacheHttpClientContext;
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/httpcomponents/DefaultApacheHttpClientObservationConvention.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2022 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.core.instrument.binder.httpcomponents;
+
+import io.micrometer.common.KeyValues;
+import io.micrometer.common.lang.Nullable;
+import org.apache.http.HttpRequest;
+import org.apache.http.HttpResponse;
+
+/**
+ * Default implementation of {@link ApacheHttpClientObservationConvention}.
+ *
+ * @since 1.10.0
+ * @see ApacheHttpClientDocumentedObservation
+ */
+public class DefaultApacheHttpClientObservationConvention implements ApacheHttpClientObservationConvention {
+
+    /**
+     * Singleton instance of this convention.
+     */
+    public static final DefaultApacheHttpClientObservationConvention INSTANCE = new DefaultApacheHttpClientObservationConvention();
+
+    // There is no need to instantiate this class multiple times, but it may be extended,
+    // hence protected visibility.
+    protected DefaultApacheHttpClientObservationConvention() {
+    }
+
+    @Override
+    public String getName() {
+        return MicrometerHttpRequestExecutor.METER_NAME;
+    }
+
+    @Override
+    public String getContextualName(ApacheHttpClientContext context) {
+        return "HTTP " + getMethodString(context.getCarrier());
+    }
+
+    @Override
+    public KeyValues getLowCardinalityKeyValues(ApacheHttpClientContext context) {
+        KeyValues keyValues = KeyValues.of(
+                ApacheHttpClientDocumentedObservation.ApacheHttpClientTags.METHOD
+                        .withValue(getMethodString(context.getCarrier())),
+                ApacheHttpClientDocumentedObservation.ApacheHttpClientTags.URI
+                        .withValue(context.getUriMapper().apply(context.getCarrier())),
+                ApacheHttpClientDocumentedObservation.ApacheHttpClientTags.STATUS
+                        .withValue(getStatusValue(context.getResponse())));
+        if (context.shouldExportTagsForRoute()) {
+            keyValues = keyValues.and(HttpContextUtils.generateTagStringsForRoute(context.getApacheHttpContext()));
+        }
+        return keyValues;
+    }
+
+    String getStatusValue(@Nullable HttpResponse response) {
+        return response != null ? Integer.toString(response.getStatusLine().getStatusCode()) : "CLIENT_ERROR";
+    }
+
+    String getMethodString(@Nullable HttpRequest request) {
+        return request != null && request.getRequestLine().getMethod() != null ? request.getRequestLine().getMethod()
+                : "UNKNOWN";
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/httpcomponents/HttpContextUtils.java

@@ -23,6 +23,10 @@
 class HttpContextUtils {
 
     static Tags generateTagsForRoute(HttpContext context) {
+        return Tags.of(generateTagStringsForRoute(context));
+    }
+
+    static String[] generateTagStringsForRoute(HttpContext context) {
         String targetScheme = "UNKNOWN";
         String targetHost = "UNKNOWN";
         String targetPort = "UNKNOWN";
@@ -33,7 +37,10 @@ static Tags generateTagsForRoute(HttpContext context) {
             targetHost = host.getHostName();
             targetPort = String.valueOf(host.getPort());
         }
-        return Tags.of("target.scheme", targetScheme, "target.host", targetHost, "target.port", targetPort);
+        return new String[] { ApacheHttpClientDocumentedObservation.ApacheHttpClientTags.TARGET_SCHEME.asString(),
+                targetScheme, ApacheHttpClientDocumentedObservation.ApacheHttpClientTags.TARGET_HOST.asString(),
+                targetHost, ApacheHttpClientDocumentedObservation.ApacheHttpClientTags.TARGET_PORT.asString(),
+                targetPort };
     }
 
 }