HADOOP-15357. Configuration.getPropsWithPrefix no longer does variable substitution. Contributed by Jim Brennan

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java

@@ -2869,15 +2869,12 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
    */
   public Map<String, String> getPropsWithPrefix(String confPrefix) {
     Properties props = getProps();
-    Enumeration e = props.propertyNames();
     Map<String, String> configMap = new HashMap<>();
-    String name = null;
-    while (e.hasMoreElements()) {
-      name = (String) e.nextElement();
+    for (String name : props.stringPropertyNames()) {
       if (name.startsWith(confPrefix)) {
-        String value = props.getProperty(name);
-        name = name.substring(confPrefix.length());
-        configMap.put(name, value);
+        String value = get(name);
+        String keyName = name.substring(confPrefix.length());
+        configMap.put(keyName, value);
       }
     }
     return configMap;

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestConfiguration.java

@@ -2320,19 +2320,33 @@ public class TestConfiguration {
     FileUtil.fullyDelete(tmpDir);
   }
 
+  @Test
   public void testGettingPropertiesWithPrefix() throws Exception {
     Configuration conf = new Configuration();
     for (int i = 0; i < 10; i++) {
-      conf.set("prefix" + ".name" + i, "value");
+      conf.set("prefix." + "name" + i, "value" + i);
     }
     conf.set("different.prefix" + ".name", "value");
-    Map<String, String> props = conf.getPropsWithPrefix("prefix");
-    assertEquals(props.size(), 10);
+    Map<String, String> prefixedProps = conf.getPropsWithPrefix("prefix.");
+    assertEquals(prefixedProps.size(), 10);
+    for (int i = 0; i < 10; i++) {
+      assertEquals("value" + i, prefixedProps.get("name" + i));
+    }
 
+    // Repeat test with variable substitution
+    conf.set("foo", "bar");
+    for (int i = 0; i < 10; i++) {
+      conf.set("subprefix." + "subname" + i, "value_${foo}" + i);
+    }
+    prefixedProps = conf.getPropsWithPrefix("subprefix.");
+    assertEquals(prefixedProps.size(), 10);
+    for (int i = 0; i < 10; i++) {
+      assertEquals("value_bar" + i, prefixedProps.get("subname" + i));
+    }
     // test call with no properties for a given prefix
-    props = conf.getPropsWithPrefix("none");
-    assertNotNull(props.isEmpty());
-    assertTrue(props.isEmpty());
+    prefixedProps = conf.getPropsWithPrefix("none");
+    assertNotNull(prefixedProps.isEmpty());
+    assertTrue(prefixedProps.isEmpty());
   }
 
   public static void main(String[] argv) throws Exception {