Allow use of custom DatadogConfig without requiring api-key property

Closes gh-11979

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/datadog/DatadogMetricsExportAutoConfiguration.java

@@ -24,9 +24,9 @@ import org.springframework.boot.actuate.autoconfigure.metrics.MetricsAutoConfigu
 import org.springframework.boot.actuate.autoconfigure.metrics.export.simple.SimpleMetricsExportAutoConfiguration;
 import org.springframework.boot.autoconfigure.AutoConfigureBefore;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+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.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -41,7 +41,7 @@ import org.springframework.context.annotation.Configuration;
 @AutoConfigureBefore({ MetricsAutoConfiguration.class,
 		SimpleMetricsExportAutoConfiguration.class })
 @ConditionalOnClass(DatadogMeterRegistry.class)
-@ConditionalOnProperty("management.metrics.export.datadog.api-key")
+@ConditionalOnBean(Clock.class)
 @EnableConfigurationProperties(DatadogProperties.class)
 public class DatadogMetricsExportAutoConfiguration {
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/SpringApplicationHierarchyTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.actuate.autoconfigure;
 import org.junit.After;
 import org.junit.Test;
 
+import org.springframework.boot.actuate.autoconfigure.metrics.export.datadog.DatadogMetricsExportAutoConfiguration;
 import org.springframework.boot.actuate.autoconfigure.metrics.export.jmx.JmxMetricsExportAutoConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration;
@@ -72,8 +73,8 @@ public class SpringApplicationHierarchyTests {
 			MongoDataAutoConfiguration.class, Neo4jDataAutoConfiguration.class,
 			Neo4jRepositoriesAutoConfiguration.class, RedisAutoConfiguration.class,
 			RedisRepositoriesAutoConfiguration.class, FlywayAutoConfiguration.class,
-			JestAutoConfiguration.class,
-			JmxMetricsExportAutoConfiguration.class }, excludeName = {
+			JestAutoConfiguration.class, JmxMetricsExportAutoConfiguration.class,
+			DatadogMetricsExportAutoConfiguration.class }, excludeName = {
 					"org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchAutoConfiguration" })
 	public static class Child {
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/export/datadog/DatadogMetricsExportAutoConfigurationTests.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2012-2018 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.boot.actuate.autoconfigure.metrics.export.datadog;
+
+import io.micrometer.core.instrument.Clock;
+import io.micrometer.datadog.DatadogConfig;
+import io.micrometer.datadog.DatadogMeterRegistry;
+import org.junit.Test;
+
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link DatadogMetricsExportAutoConfiguration}
+ *
+ * @author Andy Wilkinson
+ */
+public class DatadogMetricsExportAutoConfigurationTests {
+
+	private final ApplicationContextRunner runner = new ApplicationContextRunner()
+			.withConfiguration(
+					AutoConfigurations.of(DatadogMetricsExportAutoConfiguration.class));
+
+	@Test
+	public void backsOffWithoutAClock() {
+		this.runner.run((context) -> assertThat(context)
+				.doesNotHaveBean(DatadogMeterRegistry.class));
+	}
+
+	@Test
+	public void failsWithoutAnApiKey() {
+		this.runner.withUserConfiguration(BaseConfiguration.class)
+				.run((context) -> assertThat(context).hasFailed());
+	}
+
+	@Test
+	public void autoConfiguresItsConfigAndMeterRegistry() {
+		this.runner.withUserConfiguration(BaseConfiguration.class)
+				.withPropertyValues("management.metrics.export.datadog.api-key=abcde")
+				.run((context) -> assertThat(context)
+						.hasSingleBean(DatadogMeterRegistry.class)
+						.hasSingleBean(DatadogConfig.class));
+	}
+
+	@Test
+	public void allowsCustomConfigToBeUsed() {
+		this.runner.withUserConfiguration(CustomConfigConfiguration.class)
+				.run((context) -> assertThat(context)
+						.hasSingleBean(DatadogMeterRegistry.class)
+						.hasSingleBean(DatadogConfig.class).hasBean("customConfig"));
+	}
+
+	@Test
+	public void allowsCustomRegistryToBeUsed() {
+		this.runner.withUserConfiguration(CustomRegistryConfiguration.class)
+				.withPropertyValues("management.metrics.export.datadog.api-key=abcde")
+				.run((context) -> assertThat(context)
+						.hasSingleBean(DatadogMeterRegistry.class)
+						.hasBean("customRegistry").hasSingleBean(DatadogConfig.class));
+	}
+
+	@Configuration
+	static class BaseConfiguration {
+
+		@Bean
+		public Clock clock() {
+			return Clock.SYSTEM;
+		}
+
+	}
+
+	@Configuration
+	@Import(BaseConfiguration.class)
+	static class CustomConfigConfiguration {
+
+		@Bean
+		public DatadogConfig customConfig() {
+			return new DatadogConfig() {
+
+				@Override
+				public String get(String k) {
+					if ("datadog.apiKey".equals(k)) {
+						return "12345";
+					}
+					return null;
+				}
+
+			};
+		}
+
+	}
+
+	@Configuration
+	@Import(BaseConfiguration.class)
+	static class CustomRegistryConfiguration {
+
+		@Bean
+		public DatadogMeterRegistry customRegistry(DatadogConfig config, Clock clock) {
+			return new DatadogMeterRegistry(config, clock);
+		}
+
+	}
+
+}