Fix loading of devtools yaml files

Fixes gh-19081

spring-boot-project/spring-boot-devtools/pom.xml

@@ -206,6 +206,11 @@
 			<artifactId>thymeleaf-spring5</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.yaml</groupId>
+			<artifactId>snakeyaml</artifactId>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>nz.net.ultraq.thymeleaf</groupId>
 			<artifactId>thymeleaf-layout-dialect</artifactId>

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/env/DevToolsHomePropertiesPostProcessor.java

@@ -19,18 +19,23 @@ package org.springframework.boot.devtools.env;
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
-import java.util.Properties;
+import java.util.Set;
 import java.util.function.Function;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.devtools.system.DevToolsEnablementDeducer;
 import org.springframework.boot.env.EnvironmentPostProcessor;
+import org.springframework.boot.env.PropertiesPropertySourceLoader;
+import org.springframework.boot.env.PropertySourceLoader;
+import org.springframework.boot.env.YamlPropertySourceLoader;
 import org.springframework.core.env.ConfigurableEnvironment;
-import org.springframework.core.env.PropertiesPropertySource;
 import org.springframework.core.env.PropertySource;
 import org.springframework.core.io.FileSystemResource;
-import org.springframework.core.io.support.PropertiesLoaderUtils;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -52,6 +57,17 @@ public class DevToolsHomePropertiesPostProcessor implements EnvironmentPostProce
 
 	private static final String CONFIG_PATH = "/.config/spring-boot/";
 
+	private static final Set<PropertySourceLoader> PROPERTY_SOURCE_LOADERS;
+
+	static {
+		Set<PropertySourceLoader> propertySourceLoaders = new HashSet<>();
+		propertySourceLoaders.add(new PropertiesPropertySourceLoader());
+		if (ClassUtils.isPresent("org.yaml.snakeyaml.Yaml", null)) {
+			propertySourceLoaders.add(new YamlPropertySourceLoader());
+		}
+		PROPERTY_SOURCE_LOADERS = Collections.unmodifiableSet(propertySourceLoaders);
+	}
+
 	@Override
 	public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
 		if (DevToolsEnablementDeducer.shouldEnable(Thread.currentThread())) {
@@ -88,15 +104,23 @@ public class DevToolsHomePropertiesPostProcessor implements EnvironmentPostProce
 	private void addPropertySource(List<PropertySource<?>> propertySources, FileSystemResource resource,
 			Function<File, String> propertySourceNamer) {
 		try {
-			Properties properties = PropertiesLoaderUtils.loadProperties(resource);
 			String name = propertySourceNamer.apply(resource.getFile());
-			propertySources.add(new PropertiesPropertySource(name, properties));
+			for (PropertySourceLoader loader : PROPERTY_SOURCE_LOADERS) {
+				if (canLoadFileExtension(loader, resource.getFilename())) {
+					propertySources.addAll(loader.load(name, resource));
+				}
+			}
 		}
 		catch (IOException ex) {
 			throw new IllegalStateException("Unable to load " + resource.getFilename(), ex);
 		}
 	}
 
+	private boolean canLoadFileExtension(PropertySourceLoader loader, String name) {
+		return Arrays.stream(loader.getFileExtensions())
+				.anyMatch((fileExtension) -> StringUtils.endsWithIgnoreCase(name, fileExtension));
+	}
+
 	protected File getHomeFolder() {
 		String home = System.getProperty("user.home");
 		if (StringUtils.hasLength(home)) {

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/env/DevToolsHomePropertiesPostProcessorTests.java

@@ -20,6 +20,7 @@ import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.file.Files;
 import java.util.Properties;
 
 import org.junit.jupiter.api.BeforeEach;
@@ -27,6 +28,7 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
 import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.io.ClassPathResource;
 import org.springframework.mock.env.MockEnvironment;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -74,42 +76,41 @@ class DevToolsHomePropertiesPostProcessorTests {
 
 	@Test
 	void loadsPropertiesFromConfigFolderUsingYml() throws Exception {
-		Properties properties = new Properties();
-		properties.put("abc", "def");
 		OutputStream out = new FileOutputStream(new File(this.configDir, "spring-boot-devtools.yml"));
-		properties.store(out, null);
+		File file = new ClassPathResource("spring-devtools.yaml", getClass()).getFile();
+		byte[] content = Files.readAllBytes(file.toPath());
+		out.write(content);
 		out.close();
 		ConfigurableEnvironment environment = getPostProcessedEnvironment();
-		assertThat(environment.getProperty("abc")).isEqualTo("def");
+		assertThat(environment.getProperty("abc.xyz")).isEqualTo("def");
 	}
 
 	@Test
 	void loadsPropertiesFromConfigFolderUsingYaml() throws Exception {
-		Properties properties = new Properties();
-		properties.put("abc", "def");
 		OutputStream out = new FileOutputStream(new File(this.configDir, "spring-boot-devtools.yaml"));
-		properties.store(out, null);
+		File file = new ClassPathResource("spring-devtools.yaml", getClass()).getFile();
+		byte[] content = Files.readAllBytes(file.toPath());
+		out.write(content);
 		out.close();
 		ConfigurableEnvironment environment = getPostProcessedEnvironment();
-		assertThat(environment.getProperty("abc")).isEqualTo("def");
+		assertThat(environment.getProperty("abc.xyz")).isEqualTo("def");
 	}
 
 	@Test
 	void loadFromConfigFolderWithPropertiesTakingPrecedence() throws Exception {
-		Properties properties = new Properties();
-		properties.put("abc", "def");
-		properties.put("bar", "baz");
 		OutputStream out = new FileOutputStream(new File(this.configDir, "spring-boot-devtools.yaml"));
-		properties.store(out, null);
+		File file = new ClassPathResource("spring-devtools.yaml", getClass()).getFile();
+		byte[] content = Files.readAllBytes(file.toPath());
+		out.write(content);
 		out.close();
 		Properties properties2 = new Properties();
-		properties2.put("abc", "jkl");
+		properties2.put("abc.xyz", "jkl");
 		OutputStream out2 = new FileOutputStream(new File(this.configDir, "spring-boot-devtools.properties"));
 		properties2.store(out2, null);
 		out2.close();
 		ConfigurableEnvironment environment = getPostProcessedEnvironment();
-		assertThat(environment.getProperty("abc")).isEqualTo("jkl");
-		assertThat(environment.getProperty("bar")).isEqualTo("baz");
+		assertThat(environment.getProperty("abc.xyz")).isEqualTo("jkl");
+		assertThat(environment.getProperty("bing")).isEqualTo("blip");
 	}
 
 	@Test
@@ -131,16 +132,16 @@ class DevToolsHomePropertiesPostProcessorTests {
 	@Test
 	void loadFromConfigFolderWithYamlTakesPrecedenceOverHomeFolder() throws Exception {
 		Properties properties = new Properties();
-		properties.put("abc", "def");
+		properties.put("abc.xyz", "jkl");
 		properties.put("bar", "baz");
 		writeFile(properties, ".spring-boot-devtools.properties");
-		Properties properties2 = new Properties();
-		properties2.put("abc", "jkl");
 		OutputStream out2 = new FileOutputStream(new File(this.configDir, "spring-boot-devtools.yml"));
-		properties2.store(out2, null);
+		File file = new ClassPathResource("spring-devtools.yaml", getClass()).getFile();
+		byte[] content = Files.readAllBytes(file.toPath());
+		out2.write(content);
 		out2.close();
 		ConfigurableEnvironment environment = getPostProcessedEnvironment();
-		assertThat(environment.getProperty("abc")).isEqualTo("jkl");
+		assertThat(environment.getProperty("abc.xyz")).isEqualTo("def");
 		assertThat(environment.getProperty("bar")).isEqualTo(null);
 	}
 

spring-boot-project/spring-boot-devtools/src/test/resources/org/springframework/boot/devtools/env/spring-devtools.yaml

@@ -0,0 +1,3 @@
+abc:
+  xyz: def
+bing: blip