Add Retrofit sample (#46)

* Created retrofit sample

* Removed target tags

* Improve tests (check logs, metrics and spans)

* retrofit -> micrometer-samples-boot3-retrofit

* format

* Add license

---------

Co-authored-by: Jonatan Ivanov <[email protected]>

micrometer-samples-boot3-retrofit/build.gradle

@@ -0,0 +1,44 @@
+buildscript {
+	repositories {
+		gradlePluginPortal()
+		if (springBootVersion.endsWith('SNAPSHOT') || springCloudVersion.endsWith('SNAPSHOT')) {
+			maven { url 'https://repo.spring.io/snapshot' }
+		}
+	}
+	dependencies {
+		classpath "org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}"
+	}
+}
+
+apply plugin: 'org.springframework.boot'
+
+dependencies {
+	implementation platform("org.springframework.boot:spring-boot-dependencies:${springBootVersion}")
+
+	implementation 'org.springframework.boot:spring-boot-starter-web'
+	implementation 'org.springframework.boot:spring-boot-starter-actuator'
+	implementation 'io.micrometer:micrometer-registry-prometheus'
+	implementation 'com.squareup.retrofit2:retrofit:latest.release'
+	implementation 'com.squareup.retrofit2:converter-scalars:latest.release'
+
+	// Default is Brave + Zipkin, you can opt in via "-Pwavefront" to Wavefront and "-Potel" for OTel
+	if (project.hasProperty('wavefront')) {
+		implementation 'io.micrometer:micrometer-tracing-reporter-wavefront'
+	}
+	if (project.hasProperty('otel')) {
+		implementation 'io.micrometer:micrometer-tracing-bridge-otel'
+		implementation 'io.opentelemetry:opentelemetry-exporter-zipkin'
+	}
+	else {
+		implementation 'io.micrometer:micrometer-tracing-bridge-brave'
+		implementation 'io.zipkin.reporter2:zipkin-reporter-brave'
+	}
+
+	testImplementation platform('org.testcontainers:testcontainers-bom:1.+')
+	testImplementation 'org.springframework.boot:spring-boot-starter-test'
+	testImplementation 'com.github.tomakehurst:wiremock-jre8-standalone:latest.release'
+	testImplementation 'io.micrometer:micrometer-test'
+	testImplementation 'io.rest-assured:rest-assured'
+	testImplementation 'org.testcontainers:junit-jupiter'
+	testImplementation 'org.awaitility:awaitility'
+}

micrometer-samples-boot3-retrofit/src/main/java/com/example/micrometer/GreetingClient.java

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+/*
+ * Copyright 2023 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 com.example.micrometer;
+
+import retrofit2.Call;
+import retrofit2.http.GET;
+import retrofit2.http.Path;
+
+public interface GreetingClient {
+
+    @GET("/greeting/{name}")
+    Call<String> getGreeting(@Path("name") String name);
+
+}

micrometer-samples-boot3-retrofit/src/main/java/com/example/micrometer/RetrofitApplication.java

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+/*
+ * Copyright 2023 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 com.example.micrometer;
+
+import io.micrometer.core.instrument.binder.okhttp3.OkHttpObservationInterceptor;
+import io.micrometer.observation.ObservationRegistry;
+import okhttp3.OkHttpClient;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import retrofit2.Retrofit;
+import retrofit2.converter.scalars.ScalarsConverterFactory;
+
+@SpringBootApplication
+public class RetrofitApplication {
+
+    public static void main(String... args) {
+        SpringApplication.run(RetrofitApplication.class, args);
+    }
+
+    @Bean
+    GreetingClient greetingClient(ObservationRegistry observationRegistry,
+            @Value("${greeting.endpoint}") String greetingEndpoint) {
+        return new Retrofit.Builder().baseUrl(greetingEndpoint)
+            .client(new OkHttpClient.Builder()
+                .addInterceptor(
+                        OkHttpObservationInterceptor.builder(observationRegistry, "http.client.requests").build())
+                .build())
+            .addConverterFactory(ScalarsConverterFactory.create())
+            .build()
+            .create(GreetingClient.class);
+    }
+
+}

micrometer-samples-boot3-retrofit/src/main/java/com/example/micrometer/SampleController.java

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+/*
+ * Copyright 2023 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 com.example.micrometer;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.io.IOException;
+import java.util.Map;
+
+@RestController
+public class SampleController {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(SampleController.class);
+
+    private final GreetingClient client;
+
+    public SampleController(GreetingClient client) {
+        this.client = client;
+    }
+
+    @GetMapping("/greet/{name}")
+    Map<String, String> greet(@PathVariable String name) throws IOException {
+        LOGGER.info("<TEST_MARKER> Greeting {}...", name);
+        return Map.of("greeting", client.getGreeting(name).execute().body());
+    }
+
+    @GetMapping("/greeting/{name}")
+    String greeting(@PathVariable String name) {
+        return "Hi %s!".formatted(name);
+    }
+
+}

micrometer-samples-boot3-retrofit/src/main/resources/application.properties

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+#
+# Copyright 2023 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.
+#
+spring.application.name=boot3-retrofit-sample
+server.port=8080
+
+management.endpoints.web.exposure.include=*
+management.tracing.sampling.probability=1.0
+management.metrics.distribution.percentiles-histogram.http.server.requests=true
+management.metrics.distribution.percentiles-histogram.http.client.requests=true
+
+spring.output.ansi.enabled=always
+logging.pattern.level=%5p [${spring.application.name:},%X{traceId:-},%X{spanId:-}]
+logging.level.org.springframework.web.servlet.DispatcherServlet=DEBUG
+
+greeting.endpoint=http://localhost:${server.port}