Restrict wildcard pattern support for configuration files

This commit restricts how wildcards can be used in search
locations for property files. If a search location contains
a pattern, there must be only one '*' and the location should
end with a '*/'. For search locations that specify the file
name, the pattern should end with '*/<filename>'.

The list of files read from wildcard locations are now sorted
alphabetically according to the absolute path of the file.

Closes gh-21217

Author: mbhave

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -499,7 +499,8 @@ For example, if you have some Redis configuration and some MySQL configuration,
 This might result in two separate `application.properties` files mounted at different locations such as `/config/redis/application.properties` and `/config/mysql/application.properties`.
 In such a case, having a wildcard location of `config/*/`, will result in both files being processed.
 
-NOTE: Locations with wildcards are not processed in a deterministic order and files that match the wildcard cannot be used to override keys in the other.
+NOTE: A wildcard location must contain only one `*` and end with `*/` for search locations that are directories or `*/<filename>` for search locations that are files.
+Locations with wildcards are sorted alphabetically based on the absolute path of the file names.
 
 
 [[boot-features-external-config-application-json]]

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigFileApplicationListener.java

@@ -16,10 +16,12 @@
 
 package org.springframework.boot.context.config;
 
+import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Deque;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -28,9 +30,12 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.function.BiConsumer;
+import java.util.function.Function;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.apache.commons.logging.Log;
 
@@ -60,9 +65,9 @@
 import org.springframework.core.env.Profiles;
 import org.springframework.core.env.PropertySource;
 import org.springframework.core.io.DefaultResourceLoader;
+import org.springframework.core.io.FileSystemResource;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
-import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
 import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.core.io.support.SpringFactoriesLoader;
 import org.springframework.util.Assert;
@@ -163,6 +168,8 @@ public class ConfigFileApplicationListener implements EnvironmentPostProcessor,
 
 	private static final Resource[] EMPTY_RESOURCES = {};
 
+	private static final Comparator<File> FILE_COMPARATOR = Comparator.comparing(File::getAbsolutePath);
+
 	private String searchLocations;
 
 	private String names;
@@ -304,8 +311,6 @@ private class Loader {
 
 		private final ResourceLoader resourceLoader;
 
-		private final PathMatchingResourcePatternResolver patternResolver;
-
 		private final List<PropertySourceLoader> propertySourceLoaders;
 
 		private Deque<Profile> profiles;
@@ -325,7 +330,6 @@ private class Loader {
 					: new DefaultResourceLoader(getClass().getClassLoader());
 			this.propertySourceLoaders = SpringFactoriesLoader.loadFactories(PropertySourceLoader.class,
 					getClass().getClassLoader());
-			this.patternResolver = new PathMatchingResourcePatternResolver(this.resourceLoader);
 		}
 
 		void load() {
@@ -555,9 +559,22 @@ private void load(PropertySourceLoader loader, String location, Profile profile,
 
 		private Resource[] getResources(String location) {
 			try {
-				return this.patternResolver.getResources(location);
+				if (location.contains("*")) {
+					String directoryPath = location.substring(0, location.indexOf("*/"));
+					String fileName = location.substring(location.lastIndexOf("/") + 1);
+					Resource resource = this.resourceLoader.getResource(directoryPath);
+					File[] files = resource.getFile().listFiles(File::isDirectory);
+					if (files != null) {
+						Arrays.sort(files, FILE_COMPARATOR);
+						return Arrays.stream(files).map((file) -> file.listFiles((dir, name) -> name.equals(fileName)))
+								.filter(Objects::nonNull).flatMap((Function<File[], Stream<File>>) Arrays::stream)
+								.map(FileSystemResource::new).toArray(Resource[]::new);
+					}
+					return EMPTY_RESOURCES;
+				}
+				return new Resource[] { this.resourceLoader.getResource(location) };
 			}
-			catch (IOException ex) {
+			catch (Exception ex) {
 				return EMPTY_RESOURCES;
 			}
 		}
@@ -658,7 +675,8 @@ private Set<String> getSearchLocations(String propertyName) {
 					if (!path.contains("$")) {
 						path = StringUtils.cleanPath(path);
 						Assert.state(!path.startsWith(ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX),
-								"Classpath wildard patterns cannot be used as a search location");
+								"Classpath wildcard patterns cannot be used as a search location");
+						validateWildcardLocation(path);
 						if (!ResourceUtils.isUrl(path)) {
 							path = ResourceUtils.FILE_URL_PREFIX + path;
 						}
@@ -669,6 +687,15 @@ private Set<String> getSearchLocations(String propertyName) {
 			return locations;
 		}
 
+		private void validateWildcardLocation(String path) {
+			if (path.contains("*")) {
+				Assert.state(StringUtils.countOccurrencesOf(path, "*") == 1,
+						"Wildard pattern with multiple '*'s cannot be used as search location");
+				String directoryPath = path.substring(0, path.lastIndexOf("/") + 1);
+				Assert.state(directoryPath.endsWith("*/"), "Wildcard patterns must end with '*/'");
+			}
+		}
+
 		private Set<String> getSearchNames() {
 			if (this.environment.containsProperty(CONFIG_NAME_PROPERTY)) {
 				String property = this.environment.getProperty(CONFIG_NAME_PROPERTY);

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigFileApplicationListenerTests.java

@@ -716,7 +716,7 @@ void classpathWildcardResourceThrowsException() {
 				"spring.config.location=classpath*:override.properties");
 		assertThatIllegalStateException()
 				.isThrownBy(() -> this.initializer.postProcessEnvironment(this.environment, this.application))
-				.withMessage("Classpath wildard patterns cannot be used as a search location");
+				.withMessage("Classpath wildcard patterns cannot be used as a search location");
 	}
 
 	@Test
@@ -1032,6 +1032,36 @@ void whenConfigLocationSpecifiesDirectoryConfigFileProcessingContinues() {
 		this.initializer.postProcessEnvironment(this.environment, this.application);
 	}
 
+	@Test
+	void directoryLocationsWithWildcardShouldHaveWildcardAsLastCharacterBeforeSlash() {
+		String location = "file:src/test/resources/*/config/";
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.environment,
+				"spring.config.location=" + location);
+		assertThatIllegalStateException()
+				.isThrownBy(() -> this.initializer.postProcessEnvironment(this.environment, this.application))
+				.withMessage("Wildcard patterns must end with '*/'");
+	}
+
+	@Test
+	void directoryLocationsWithMultipleWildcardsShouldThrowException() {
+		String location = "file:src/test/resources/config/**/";
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.environment,
+				"spring.config.location=" + location);
+		assertThatIllegalStateException()
+				.isThrownBy(() -> this.initializer.postProcessEnvironment(this.environment, this.application))
+				.withMessage("Wildard pattern with multiple '*'s cannot be used as search location");
+	}
+
+	@Test
+	void locationsWithWildcardDirectoriesShouldRestrictToOneLevelDeep() {
+		String location = "file:src/test/resources/config/*/";
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.environment,
+				"spring.config.location=" + location);
+		this.initializer.setSearchNames("testproperties");
+		this.initializer.postProcessEnvironment(this.environment, this.application);
+		assertThat(this.environment.getProperty("third.property")).isNull();
+	}
+
 	@Test
 	void locationsWithWildcardDirectoriesShouldLoadAllFilesThatMatch() {
 		String location = "file:src/test/resources/config/*/";
@@ -1045,6 +1075,22 @@ void locationsWithWildcardDirectoriesShouldLoadAllFilesThatMatch() {
 		assertThat(second).isEqualTo("ball");
 	}
 
+	@Test
+	void locationsWithWildcardDirectoriesShouldSortAlphabeticallyBasedOnAbsolutePath() {
+		String location = "file:src/test/resources/config/*/";
+		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(this.environment,
+				"spring.config.location=" + location);
+		this.initializer.setSearchNames("testproperties");
+		this.initializer.postProcessEnvironment(this.environment, this.application);
+		List<String> sources = this.environment.getPropertySources().stream()
+				.filter((source) -> source.getName().contains("applicationConfig")).map((source) -> {
+					String name = source.getName();
+					return name.substring(name.indexOf("src/test/resources"));
+				}).collect(Collectors.toList());
+		assertThat(sources).containsExactly("src/test/resources/config/1-first/testproperties.properties]]",
+				"src/test/resources/config/2-second/testproperties.properties]]");
+	}
+
 	@Test
 	void locationsWithWildcardFilesShouldLoadAllFilesThatMatch() {
 		String location = "file:src/test/resources/config/*/testproperties.properties";

spring-boot-project/spring-boot/src/test/resources/config/nested/3-third/testproperties.properties

@@ -0,0 +1 @@
+third.property=shouldnotbefound