Added consistency between metric and metrics

without this change we have 2 different properties. One is `spring.sleuth.metric` and the other is `spring.sleuth.metrics`.
with this change we're introducing conditionality on `spring.sleuth.metric.enabled`

fixes #477

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/metric/SleuthMetricProperties.java

@@ -11,6 +11,16 @@ import org.springframework.boot.context.properties.ConfigurationProperties;
 @ConfigurationProperties("spring.sleuth.metric")
 public class SleuthMetricProperties {
 
+	private boolean enabled;
+
+	public boolean isEnabled() {
+		return this.enabled;
+	}
+
+	public void setEnabled(boolean enabled) {
+		this.enabled = enabled;
+	}
+
 	private Span span = new Span();
 
 	public Span getSpan() {

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/metric/TraceMetricsAutoConfiguration.java

@@ -16,15 +16,23 @@
 
 package org.springframework.cloud.sleuth.metric;
 
+import java.lang.invoke.MethodHandles;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.boot.actuate.metrics.CounterService;
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.type.AnnotatedTypeMetadata;
 
 /**
  * {@link org.springframework.boot.autoconfigure.EnableAutoConfiguration Auto-configuration}
@@ -34,7 +42,7 @@ import org.springframework.context.annotation.Configuration;
  * @since 1.0.0
  */
 @Configuration
-@ConditionalOnProperty(value="spring.sleuth.metrics.enabled", matchIfMissing=true)
+@Conditional(TraceMetricsAutoConfiguration.PickMetricIfMetricsIsMissing.class)
 @EnableConfigurationProperties
 public class TraceMetricsAutoConfiguration {
 
@@ -69,4 +77,34 @@ public class TraceMetricsAutoConfiguration {
 	public SpanMetricReporter noOpSpanReporterCounterService() {
 		return new NoOpSpanMetricReporter();
 	}
+
+	static class PickMetricIfMetricsIsMissing extends SpringBootCondition {
+
+		private static final Log log = LogFactory.getLog(MethodHandles.lookup().lookupClass());
+
+		static final String DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED = "spring.sleuth.metrics.enabled";
+		static final String SPRING_SLEUTH_METRIC_ENABLED = "spring.sleuth.metric.enabled";
+
+		@Override
+		public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
+			Boolean oldValue = context.getEnvironment().getProperty(DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED, Boolean.class);
+			Boolean newValue = context.getEnvironment().getProperty(SPRING_SLEUTH_METRIC_ENABLED, Boolean.class);
+			if (oldValue != null) {
+				log.warn("You're using an old version of the metrics property. Instead of using [" +
+						DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED + "] please use [" + SPRING_SLEUTH_METRIC_ENABLED + "]");
+				return matchCondition(oldValue, DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED);
+			}
+			if (newValue != null) {
+				return matchCondition(newValue, SPRING_SLEUTH_METRIC_ENABLED);
+			}
+			return ConditionOutcome.match("No property was passed - assuming that metrics are enabled.");
+		}
+
+		private ConditionOutcome matchCondition(Boolean value, String property) {
+			if (Boolean.TRUE.equals(value)) {
+				return ConditionOutcome.match();
+			}
+			return ConditionOutcome.noMatch("Property [" + property + "] is set to false.");
+		}
+	}
 }

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/metric/TraceMetricsAutoConfigurationTests.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2013-2016 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
+ *
+ *      http://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.sleuth.metric;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.BDDMockito;
+import org.mockito.Mock;
+import org.mockito.runners.MockitoJUnitRunner;
+import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
+import org.springframework.cloud.sleuth.metric.TraceMetricsAutoConfiguration.PickMetricIfMetricsIsMissing;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+import org.springframework.mock.env.MockEnvironment;
+
+import static org.assertj.core.api.BDDAssertions.then;
+import static org.springframework.cloud.sleuth.metric.TraceMetricsAutoConfiguration.PickMetricIfMetricsIsMissing.DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED;
+import static org.springframework.cloud.sleuth.metric.TraceMetricsAutoConfiguration.PickMetricIfMetricsIsMissing.SPRING_SLEUTH_METRIC_ENABLED;
+
+/**
+ * @author Marcin Grzejszczak
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class TraceMetricsAutoConfigurationTests {
+
+	@Mock ConditionContext conditionContext;
+	@Mock AnnotatedTypeMetadata annotatedTypeMetadata;
+	MockEnvironment mockEnvironment = new MockEnvironment();
+
+	PickMetricIfMetricsIsMissing condition = new PickMetricIfMetricsIsMissing();
+
+	@Before
+	public void setup() {
+		BDDMockito.given(this.conditionContext.getEnvironment()).willReturn(this.mockEnvironment);
+	}
+
+	@Test
+	public void should_turn_on_the_feature_when_no_explicit_one_was_provided() {
+		ConditionOutcome outcome = this.condition.getMatchOutcome(this.conditionContext, this.annotatedTypeMetadata);
+
+		then(outcome.isMatch()).isTrue();
+	}
+
+	@Test
+	public void should_turn_on_the_feature_when_deprecated_property_is_enabled() {
+		this.mockEnvironment.setProperty(DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED, "true");
+
+		ConditionOutcome outcome = this.condition.getMatchOutcome(this.conditionContext, this.annotatedTypeMetadata);
+
+		then(outcome.isMatch()).isTrue();
+	}
+
+	@Test
+	public void should_turn_off_the_feature_when_deprecated_property_is_disabled() {
+		this.mockEnvironment.setProperty(DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED, "false");
+
+		ConditionOutcome outcome = this.condition.getMatchOutcome(this.conditionContext, this.annotatedTypeMetadata);
+
+		then(outcome.isMatch()).isFalse();
+	}
+
+	@Test
+	public void should_turn_on_the_feature_when_property_is_enabled() {
+		this.mockEnvironment.setProperty(SPRING_SLEUTH_METRIC_ENABLED, "true");
+
+		ConditionOutcome outcome = this.condition.getMatchOutcome(this.conditionContext, this.annotatedTypeMetadata);
+
+		then(outcome.isMatch()).isTrue();
+	}
+
+	@Test
+	public void should_turn_off_the_feature_when_property_is_disabled() {
+		this.mockEnvironment.setProperty(SPRING_SLEUTH_METRIC_ENABLED, "false");
+
+		ConditionOutcome outcome = this.condition.getMatchOutcome(this.conditionContext, this.annotatedTypeMetadata);
+
+		then(outcome.isMatch()).isFalse();
+	}
+
+	@Test
+	public void should_turn_on_the_feature_when_new_property_is_disabled_and_old_is_enabled() {
+		this.mockEnvironment.setProperty(DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED, "true");
+		this.mockEnvironment.setProperty(SPRING_SLEUTH_METRIC_ENABLED, "false");
+
+		ConditionOutcome outcome = this.condition.getMatchOutcome(this.conditionContext, this.annotatedTypeMetadata);
+
+		then(outcome.isMatch()).isTrue();
+	}
+
+	@Test
+	public void should_turn_off_the_feature_when_new_property_is_disabled_and_old_is_enabled() {
+		this.mockEnvironment.setProperty(DEPRECATED_SPRING_SLEUTH_METRICS_ENABLED, "false");
+		this.mockEnvironment.setProperty(SPRING_SLEUTH_METRIC_ENABLED, "true");
+
+		ConditionOutcome outcome = this.condition.getMatchOutcome(this.conditionContext, this.annotatedTypeMetadata);
+
+		then(outcome.isMatch()).isFalse();
+	}
+}