Properties from file system should be search with the same rules used…

… for environment variables (#276)

Properties from file system should be search with the same rules used for environment variables.

doc/modules/ROOT/pages/config-sources/filesystem-config-source.adoc

@@ -25,6 +25,12 @@ Nested directories are not supported.
 This Config Source can be used to read configuration from
 https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap[Kubernetes ConfigMap].
 
+The same mapping rules as defined for environment variables are applied, so the FileSystemConfigSource will search for a given property name (e.g. com.ACME.size):
+
+* Exact match (i.e. com.ACME.size)
+* Replace each character that is neither alphanumeric nor _ with _ (i.e. com_ACME_size)
+* Replace each character that is neither alphanumeric nor _ with _; then convert the name to upper case (i.e. COM_ACME_SIZE)
+
 === Usage
 
 To use the FileSystem Config Source, add the following to your Maven `pom.xml`:

sources/file-system/src/main/java/io/smallrye/config/source/file/FileSystemConfigSource.java

@@ -23,6 +23,7 @@
 import java.nio.file.Path;
 import java.util.Collections;
 import java.util.Map;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -59,6 +60,7 @@
 public class FileSystemConfigSource extends MapBackedConfigSource {
     private static final long serialVersionUID = 654034634846856045L;
 
+    private static final Pattern PATTERN = Pattern.compile("[^a-zA-Z0-9_]");
     private static final Logger LOG = Logger.getLogger("io.smallrye.config");
 
     FileSystemConfigSource(File dir) {
@@ -96,4 +98,30 @@ private static String readContent(Path file) {
             throw new UncheckedIOException(e);
         }
     }
+
+    @Override
+    public String getValue(String name) {
+        if (name == null) {
+            return null;
+        }
+
+        final Map<String, String> properties = getProperties();
+
+        // exact match
+        String value = properties.get(name);
+        if (value != null) {
+            return value;
+        }
+
+        // replace non-alphanumeric characters by underscores
+        String sanitizedName = PATTERN.matcher(name).replaceAll("_");
+
+        value = properties.get(sanitizedName);
+        if (value != null) {
+            return value;
+        }
+
+        // replace non-alphanumeric characters by underscores and convert to uppercase
+        return properties.get(sanitizedName.toUpperCase());
+    }
 }

sources/file-system/src/test/java/io/smallrye/config/source/file/FileSystemConfigSourceTestCase.java

@@ -17,6 +17,7 @@
 package io.smallrye.config.source.file;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
 
 import java.io.File;
 import java.net.URISyntaxException;
@@ -42,4 +43,20 @@ public void testConfigSourceFromDir() throws URISyntaxException {
         assertEquals("myValue1", configSource.getValue("myKey1"));
         assertEquals("true", configSource.getValue("myKey2"));
     }
+
+    @Test
+    public void testCharacterReplacement() throws URISyntaxException {
+        URL configDirURL = this.getClass().getResource("configDir");
+        File dir = new File(configDirURL.toURI());
+
+        ConfigSource configSource = new FileSystemConfigSource(dir);
+        // the non-alphanumeric chars may be replaced by _ 
+        assertEquals("http://localhost:8080/my-service", configSource.getValue("MyService/mp-rest/url"));
+        // or the file name is uppercased
+        assertEquals("http://localhost:8080/other-service", configSource.getValue("OtherService/mp-rest/url"));
+        // but the key is still case sensitive 
+        assertNull(configSource.getValue("myservice/mp-rest/url"));
+        // you can't rewrite the key, only the file name 
+        assertNull(configSource.getValue("MYSERVICE_MP_REST_URL"));
+    }
 }

sources/file-system/src/test/resources/io/smallrye/config/source/file/configDir/MyService_mp_rest_url

@@ -0,0 +1 @@
+http://localhost:8080/my-service

sources/file-system/src/test/resources/io/smallrye/config/source/file/configDir/OTHERSERVICE_MP_REST_URL

@@ -0,0 +1 @@
+http://localhost:8080/other-service