Use config map name for configtree property sources

When Kubernetes mounts config maps onto volumes in a pod, it creates
hidden files on the pod filesystem with symbolic links to the
hidden files. The symlinks are named for the user-provided config
map that was mounted, while the hidden files have system-generated
names.

Prior to this commit, the property sources created by the
configtree property source were added to the environment using the
system-generated hidden file name instead of the user-provided
symlink name. This commit corrects that behavior so the property
sources are named as a user would expect.

Fixes gh-23232

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

@@ -25,6 +25,7 @@ import java.nio.file.attribute.BasicFileAttributes;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.EnumSet;
+import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
@@ -192,7 +193,7 @@ public class ConfigTreePropertySource extends EnumerablePropertySource<Path> imp
 		static Map<String, PropertyFile> findAll(Path sourceDirectory, Set<Option> options) {
 			try {
 				Map<String, PropertyFile> propertyFiles = new TreeMap<>();
-				Files.find(sourceDirectory, MAX_DEPTH, PropertyFile::isRegularFile).forEach((path) -> {
+				Files.find(sourceDirectory, MAX_DEPTH, PropertyFile::isPropertyFile).forEach((path) -> {
 					String name = getName(sourceDirectory.relativize(path));
 					if (StringUtils.hasText(name)) {
 						if (options.contains(Option.USE_LOWERCASE_NAMES)) {
@@ -208,8 +209,18 @@ public class ConfigTreePropertySource extends EnumerablePropertySource<Path> imp
 			}
 		}
 
-		private static boolean isRegularFile(Path path, BasicFileAttributes attributes) {
-			return attributes.isRegularFile();
+		private static boolean isPropertyFile(Path path, BasicFileAttributes attributes) {
+			return !hasHiddenPathElement(path) && (attributes.isRegularFile() || attributes.isSymbolicLink());
+		}
+
+		private static boolean hasHiddenPathElement(Path path) {
+			Iterator<Path> iterator = path.iterator();
+			while (iterator.hasNext()) {
+				if (iterator.next().toString().startsWith(".")) {
+					return true;
+				}
+			}
+			return false;
 		}
 
 		private static String getName(Path relativePath) {

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

@@ -88,6 +88,18 @@ class ConfigTreePropertySourceTests {
 		assertThat(propertySource.getPropertyNames()).containsExactly("c", "fa.a", "fa.b", "fb.a", "fb.fa.a");
 	}
 
+	@Test
+	void getPropertyNamesFromFlatWithSymlinksIgnoresHiddenFiles() throws Exception {
+		ConfigTreePropertySource propertySource = getSymlinkedFlatPropertySource();
+		assertThat(propertySource.getPropertyNames()).containsExactly("a", "b", "c");
+	}
+
+	@Test
+	void getPropertyNamesFromNestedWithSymlinksIgnoresHiddenFiles() throws Exception {
+		ConfigTreePropertySource propertySource = getSymlinkedNestedPropertySource();
+		assertThat(propertySource.getPropertyNames()).containsExactly("aa", "ab", "baa", "c");
+	}
+
 	@Test
 	void getPropertyNamesWhenLowercaseReturnsPropertyNames() throws Exception {
 		addProperty("SpRiNg", "boot");
@@ -194,6 +206,16 @@ class ConfigTreePropertySourceTests {
 		return new ConfigTreePropertySource("test", this.directory);
 	}
 
+	private ConfigTreePropertySource getSymlinkedFlatPropertySource() throws IOException {
+		addProperty("..hidden-a", "A");
+		addProperty("..hidden-b", "B");
+		addProperty("..hidden-c", "C");
+		createSymbolicLink("a", "..hidden-a");
+		createSymbolicLink("b", "..hidden-b");
+		createSymbolicLink("c", "..hidden-c");
+		return new ConfigTreePropertySource("test", this.directory);
+	}
+
 	private ConfigTreePropertySource getNestedPropertySource() throws IOException {
 		addNested();
 		return new ConfigTreePropertySource("test", this.directory);
@@ -207,10 +229,26 @@ class ConfigTreePropertySourceTests {
 		addProperty("c", "C");
 	}
 
+	private ConfigTreePropertySource getSymlinkedNestedPropertySource() throws IOException {
+		addProperty("..hidden-a/a", "AA");
+		addProperty("..hidden-a/b", "AB");
+		addProperty("..hidden-b/fa/a", "BAA");
+		addProperty("c", "C");
+		createSymbolicLink("aa", "..hidden-a/a");
+		createSymbolicLink("ab", "..hidden-a/b");
+		createSymbolicLink("baa", "..hidden-b/fa/a");
+		return new ConfigTreePropertySource("test", this.directory);
+	}
+
 	private void addProperty(String path, String value) throws IOException {
 		File file = this.directory.resolve(path).toFile();
 		file.getParentFile().mkdirs();
 		FileCopyUtils.copy(value.getBytes(StandardCharsets.UTF_8), file);
 	}
 
+	private void createSymbolicLink(String link, String target) throws IOException {
+		Files.createSymbolicLink(this.directory.resolve(link).toAbsolutePath(),
+				this.directory.resolve(target).toAbsolutePath());
+	}
+
 }