Observation instrumentation for gRPC

Add Observation instrumentation for gRPC client and server.

Closes #3427

dependencies.gradle

@@ -36,6 +36,7 @@ def VERSIONS = [
         'io.grpc:grpc-services:latest.release',
         'io.grpc:grpc-stubs:latest.release',
         'io.grpc:grpc-alts:latest.release',
+        'io.grpc:grpc-testing-proto:latest.release',
         'info.ganglia.gmetric4j:gmetric4j:latest.release',
         'io.prometheus:simpleclient_common:latest.release',
         'io.prometheus:simpleclient_pushgateway:latest.release',

micrometer-core/build.gradle

@@ -157,6 +157,10 @@ dependencies {
     }
     testImplementation("org.apache.maven.resolver:maven-resolver-connector-basic:latest.release")
     testImplementation("org.springframework:spring-core:latest.release")
+
+    // gRPC
+    testImplementation("io.grpc:grpc-core")
+    testImplementation("io.grpc:grpc-testing-proto")
 }
 
 task shenandoahTest(type: Test) {

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/grpc/DefaultGrpcClientObservationConvention.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * 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.grpc;
+
+import io.micrometer.common.KeyValue;
+import io.micrometer.common.KeyValues;
+import io.micrometer.core.instrument.binder.grpc.GrpcObservationDocumentation.LowCardinalityKeyNames;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Default convention for gRPC client. This class defines how to extract values from
+ * {@link GrpcClientObservationContext}.
+ *
+ * @author Tadaya Tsuyukubo
+ * @since 1.10.0
+ */
+public class DefaultGrpcClientObservationConvention implements GrpcClientObservationConvention {
+
+    @Override
+    public String getName() {
+        return "grpc.client";
+    }
+
+    @Override
+    public String getContextualName(GrpcClientObservationContext context) {
+        return context.getFullMethodName();
+    }
+
+    @Override
+    public KeyValues getLowCardinalityKeyValues(GrpcClientObservationContext context) {
+        List<KeyValue> keyValues = new ArrayList<>();
+        keyValues.add(LowCardinalityKeyNames.METHOD.withValue(context.getMethodName()));
+        keyValues.add(LowCardinalityKeyNames.SERVICE.withValue(context.getServiceName()));
+        keyValues.add(LowCardinalityKeyNames.METHOD_TYPE.withValue(context.getMethodType().name()));
+        if (context.getStatusCode() != null) {
+            keyValues.add(LowCardinalityKeyNames.STATUS_CODE.withValue(context.getStatusCode().name()));
+        }
+        return KeyValues.of(keyValues);
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/grpc/DefaultGrpcServerObservationConvention.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * 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.grpc;
+
+import io.micrometer.common.KeyValue;
+import io.micrometer.common.KeyValues;
+import io.micrometer.core.instrument.binder.grpc.GrpcObservationDocumentation.LowCardinalityKeyNames;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Default convention for gRPC server. This class defines how to extract values from
+ * {@link GrpcServerObservationContext}.
+ *
+ * @author Tadaya Tsuyukubo
+ * @since 1.10.0
+ */
+public class DefaultGrpcServerObservationConvention implements GrpcServerObservationConvention {
+
+    @Override
+    public String getName() {
+        return "grpc.server";
+    }
+
+    @Override
+    public String getContextualName(GrpcServerObservationContext context) {
+        return context.getFullMethodName();
+    }
+
+    @Override
+    public KeyValues getLowCardinalityKeyValues(GrpcServerObservationContext context) {
+        List<KeyValue> keyValues = new ArrayList<>();
+        keyValues.add(LowCardinalityKeyNames.METHOD.withValue(context.getMethodName()));
+        keyValues.add(LowCardinalityKeyNames.SERVICE.withValue(context.getServiceName()));
+        keyValues.add(LowCardinalityKeyNames.METHOD_TYPE.withValue(context.getMethodType().name()));
+        if (context.getStatusCode() != null) {
+            keyValues.add(LowCardinalityKeyNames.STATUS_CODE.withValue(context.getStatusCode().name()));
+        }
+        return KeyValues.of(keyValues);
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/grpc/GrpcClientObservationContext.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * 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.grpc;
+
+import io.grpc.Metadata;
+import io.grpc.MethodDescriptor.MethodType;
+import io.grpc.Status.Code;
+import io.micrometer.common.lang.Nullable;
+import io.micrometer.observation.Observation;
+import io.micrometer.observation.transport.Propagator.Setter;
+import io.micrometer.observation.transport.RequestReplySenderContext;
+
+/**
+ * {@link Observation.Context} for gRPC client.
+ *
+ * @author Tadaya Tsuyukubo
+ * @since 1.10.0
+ */
+public class GrpcClientObservationContext extends RequestReplySenderContext<Metadata, Object> {
+
+    private String serviceName;
+
+    private String methodName;
+
+    private String fullMethodName;
+
+    private MethodType methodType;
+
+    @Nullable
+    private Code statusCode;
+
+    public GrpcClientObservationContext(Setter<Metadata> setter) {
+        super(setter);
+    }
+
+    public String getServiceName() {
+        return this.serviceName;
+    }
+
+    public void setServiceName(String serviceName) {
+        this.serviceName = serviceName;
+    }
+
+    public String getMethodName() {
+        return this.methodName;
+    }
+
+    public void setMethodName(String methodName) {
+        this.methodName = methodName;
+    }
+
+    public String getFullMethodName() {
+        return this.fullMethodName;
+    }
+
+    public void setFullMethodName(String fullMethodName) {
+        this.fullMethodName = fullMethodName;
+    }
+
+    public MethodType getMethodType() {
+        return this.methodType;
+    }
+
+    public void setMethodType(MethodType methodType) {
+        this.methodType = methodType;
+    }
+
+    @Nullable
+    public Code getStatusCode() {
+        return this.statusCode;
+    }
+
+    public void setStatusCode(Code statusCode) {
+        this.statusCode = statusCode;
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/grpc/GrpcClientObservationConvention.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * 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.grpc;
+
+import io.micrometer.observation.Observation.Context;
+import io.micrometer.observation.ObservationConvention;
+
+/**
+ * {@link ObservationConvention} for gRPC client.
+ *
+ * @author Tadaya Tsuyukubo
+ * @since 1.10.0
+ */
+public interface GrpcClientObservationConvention extends ObservationConvention<GrpcClientObservationContext> {
+
+    @Override
+    default boolean supportsContext(Context context) {
+        return context instanceof GrpcClientObservationContext;
+    }
+
+}

micrometer-core/src/main/java/io/micrometer/core/instrument/binder/grpc/GrpcObservationDocumentation.java

@@ -0,0 +1,128 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * 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.grpc;
+
+import io.micrometer.common.docs.KeyName;
+import io.micrometer.observation.Observation.Context;
+import io.micrometer.observation.Observation.Event;
+import io.micrometer.observation.ObservationConvention;
+import io.micrometer.observation.docs.ObservationDocumentation;
+
+/**
+ * {@link ObservationDocumentation} for gRPC.
+ *
+ * @author Tadaya Tsuyukubo
+ * @since 1.10.0
+ */
+public enum GrpcObservationDocumentation implements ObservationDocumentation {
+
+    CLIENT {
+        @Override
+        public Class<? extends ObservationConvention<? extends Context>> getDefaultConvention() {
+            return GrpcClientObservationConvention.class;
+        }
+
+        @Override
+        public KeyName[] getLowCardinalityKeyNames() {
+            return LowCardinalityKeyNames.values();
+        }
+    },
+    SERVER {
+        @Override
+        public Class<? extends ObservationConvention<? extends Context>> getDefaultConvention() {
+            return GrpcServerObservationConvention.class;
+        }
+
+        @Override
+        public KeyName[] getLowCardinalityKeyNames() {
+            return LowCardinalityKeyNames.values();
+        }
+    };
+
+    public enum LowCardinalityKeyNames implements KeyName {
+
+        METHOD {
+            @Override
+            public String asString() {
+                return "rpc.method";
+            }
+        },
+        METHOD_TYPE {
+            @Override
+            public String asString() {
+                return "rpc.type";
+            }
+        },
+        SERVICE {
+            @Override
+            public String asString() {
+                return "rpc.service";
+            }
+        },
+        ERROR_CODE {
+            @Override
+            public String asString() {
+                return "rpc.error_code";
+            }
+        },
+        STATUS_CODE {
+            @Override
+            public String asString() {
+                return "grpc.status_code";
+            }
+        }
+
+    }
+
+    public enum GrpcClientEvents implements Event {
+
+        MESSAGE_SENT {
+            @Override
+            public String getName() {
+                return "sent";
+            }
+
+        },
+        MESSAGE_RECEIVED {
+            @Override
+            public String getName() {
+                return "received";
+            }
+
+        }
+
+    }
+
+    public enum GrpcServerEvents implements Event {
+
+        MESSAGE_RECEIVED {
+            @Override
+            public String getName() {
+                return "received";
+            }
+
+        },
+        MESSAGE_SENT {
+            @Override
+            public String getName() {
+                return "sent";
+            }
+
+        }
+
+    }
+
+}