Support Observations for CommandLineRunner and ApplicationRunner

First pass on observation

Added automatic docs generation

Renamed Observed -> Observation

Fixed copyright dates

Removed execution task listener - it makes runner spans share the same trace id

Updated version for micrometer docs to milestone

spring-cloud-task-core/src/test/java/org/springframework/cloud/task/configuration/observation/ObservationIntegrationTests.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2017-2022 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 org.springframework.cloud.task.configuration.observation;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import brave.handler.SpanHandler;
+import brave.sampler.Sampler;
+import brave.test.TestSpanHandler;
+import io.micrometer.common.KeyValues;
+import io.micrometer.core.instrument.MeterRegistry;
+import io.micrometer.core.tck.MeterRegistryAssert;
+import io.micrometer.tracing.Tracer;
+import io.micrometer.tracing.brave.bridge.BraveFinishedSpan;
+import io.micrometer.tracing.exporter.FinishedSpan;
+import io.micrometer.tracing.test.simple.SpansAssert;
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import zipkin2.Span;
+import zipkin2.reporter.Reporter;
+import zipkin2.reporter.brave.ZipkinSpanHandler;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.ApplicationRunner;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.actuate.autoconfigure.metrics.CompositeMeterRegistryAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.observation.ObservationAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.tracing.BraveAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.tracing.MicrometerTracingAutoConfiguration;
+import org.springframework.boot.actuate.autoconfigure.tracing.zipkin.ZipkinAutoConfiguration;
+import org.springframework.boot.autoconfigure.ImportAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.task.configuration.EnableTask;
+import org.springframework.cloud.task.configuration.SimpleTaskAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@SpringBootTest(classes = ObservationIntegrationTests.Config.class)
+class ObservationIntegrationTests {
+
+	@Autowired
+	TestSpanHandler testSpanHandler;
+
+	@Autowired
+	MeterRegistry meterRegistry;
+
+	@Test
+	void testSuccessfulObservation() {
+		List<FinishedSpan> finishedSpans = finishedSpans();
+
+		SpansAssert.then(finishedSpans)
+			.thenASpanWithNameEqualTo("my-command-line-runner")
+			.hasTag("spring.cloud.task.runner.bean-name", "myCommandLineRunner")
+			.backToSpans()
+			.thenASpanWithNameEqualTo("my-application-runner")
+			.hasTag("spring.cloud.task.runner.bean-name", "myApplicationRunner");
+		MeterRegistryAssert.then(this.meterRegistry)
+			.hasTimerWithNameAndTags("spring.cloud.task.runner", KeyValues.of("spring.cloud.task.runner.bean-name", "myCommandLineRunner"))
+			.hasTimerWithNameAndTags("spring.cloud.task.runner", KeyValues.of("spring.cloud.task.runner.bean-name", "myApplicationRunner"));
+	}
+
+	private List<FinishedSpan> finishedSpans() {
+		return this.testSpanHandler.spans().stream().map(BraveFinishedSpan::fromBrave).collect(Collectors.toList());
+	}
+
+	@Configuration
+	@ImportAutoConfiguration({SimpleTaskAutoConfiguration.class, ObservationAutoConfiguration.class, ObservationTaskAutoConfiguration.class, BraveAutoConfiguration.class, MicrometerTracingAutoConfiguration.class, MetricsAutoConfiguration.class, CompositeMeterRegistryAutoConfiguration.class, ZipkinAutoConfiguration.class})
+	@EnableTask
+	static class Config {
+		private static final Logger log = LoggerFactory.getLogger(Config.class);
+
+		@Bean
+		TestSpanHandler testSpanHandler() {
+			return new TestSpanHandler();
+		}
+
+		@Bean
+		SpanHandler zipkinSpanHandler(Reporter<Span> spanReporter) {
+			return ZipkinSpanHandler.newBuilder(spanReporter).build();
+		}
+
+		@Bean
+		Sampler sampler() {
+			return Sampler.ALWAYS_SAMPLE;
+		}
+
+		@Bean
+		CommandLineRunner myCommandLineRunner(Tracer tracer) {
+			return args -> log.info("<TRACE:{}> Hello from command line runner", tracer.currentSpan().context().traceId());
+		}
+
+		@Bean
+		ApplicationRunner myApplicationRunner(Tracer tracer) {
+			return args -> log.info("<TRACE:{}> Hello from application runner", tracer.currentSpan().context().traceId());
+		}
+	}
+}