Reject __settings__ as a reserved profile target

Keep default_profile resolution aligned with the other SDKs by preserving the resolved profile name and surfacing bad settings targets instead of silently falling back.

Author: simonfaltum

databricks-sdk-java/src/main/java/com/databricks/sdk/core/ConfigLoader.java

@@ -19,6 +19,7 @@
 @InternalApi
 public class ConfigLoader {
   private static final Logger LOG = LoggerFactory.getLogger(ConfigLoader.class);
+  private static final String SETTINGS_SECTION = "__settings__";
 
   private static final List<ConfigAttributeAccessor> accessors = attributeAccessors();
 
@@ -94,30 +95,36 @@ static void loadFromConfig(DatabricksConfig cfg) throws IllegalAccessException {
 
     String profile = cfg.getProfile();
     boolean hasExplicitProfile = !isNullOrEmpty(profile);
+    boolean hasDefaultProfileSetting = false;
     if (!hasExplicitProfile) {
-      SubnodeConfiguration settings = ini.getSection("__settings__");
+      SubnodeConfiguration settings = ini.getSection(SETTINGS_SECTION);
       if (settings != null && !settings.isEmpty()) {
         String defaultProfile = settings.getString("default_profile");
-        if (!isNullOrEmpty(defaultProfile) && !"__settings__".equals(defaultProfile)) {
+        if (defaultProfile != null) {
+          defaultProfile = defaultProfile.trim();
+        }
+        if (!isNullOrEmpty(defaultProfile)) {
           profile = defaultProfile;
-          hasExplicitProfile = true;
-          cfg.setProfile(profile);
+          hasDefaultProfileSetting = true;
         }
       }
     }
-    if (!hasExplicitProfile) {
+    if (!hasExplicitProfile && !hasDefaultProfileSetting) {
       profile = "DEFAULT";
     }
-    SubnodeConfiguration section = ini.getSection(profile);
+    SubnodeConfiguration section = SETTINGS_SECTION.equals(profile) ? null : ini.getSection(profile);
     boolean sectionNotPresent = section == null || section.isEmpty();
-    if (sectionNotPresent && !hasExplicitProfile) {
+    if (sectionNotPresent && !hasExplicitProfile && !hasDefaultProfileSetting) {
       LOG.info("{} has no {} profile configured", configFile, profile);
       return;
     }
     if (sectionNotPresent) {
       String msg = String.format("resolve: %s has no %s profile configured", configFile, profile);
       throw new DatabricksException(msg);
     }
+    if (hasDefaultProfileSetting) {
+      cfg.setProfile(profile);
+    }
 
     for (ConfigAttributeAccessor accessor : accessors) {
       String value = section.getString(accessor.getName());

databricks-sdk-java/src/test/java/com/databricks/sdk/DefaultProfileTest.java

@@ -73,19 +73,24 @@ public void testLegacyFallbackWhenDefaultProfileEmpty() {
     assertEquals("https://default.cloud.databricks.com", config.getHost());
   }
 
-  /** Test 5: default_profile = __settings__ is rejected and falls back to DEFAULT */
+  /** Test 5: default_profile = __settings__ is rejected */
   @Test
   public void testSettingsSelfReferenceIsRejected() {
     StaticEnv env =
         new StaticEnv()
             .with("HOME", TestOSUtils.resource("/testdata/default_profile_settings_self_ref"));
     DatabricksConfig config = createConfigWithMockClient();
-    resolveConfig(config, env);
-    config.authenticate();
 
-    // __settings__ as a profile target should be ignored, falling back to [DEFAULT]
-    assertEquals("https://default.cloud.databricks.com", config.getHost());
-    assertEquals("pat", config.getAuthType());
+    DatabricksException ex =
+        assertThrows(
+            DatabricksException.class,
+            () -> {
+              resolveConfig(config, env);
+              config.authenticate();
+            });
+    assertTrue(
+        ex.getMessage().contains("has no __settings__ profile configured"),
+        "Error should reject __settings__ as a profile target: " + ex.getMessage());
   }
 
   /** Test 6: Explicit --profile overrides default_profile */
@@ -103,6 +108,26 @@ public void testExplicitProfileOverridesDefaultProfile() {
     assertEquals("https://other.cloud.databricks.com", config.getHost());
   }
 
+  @Test
+  public void testExplicitSettingsSectionProfileIsRejected() {
+    StaticEnv env =
+        new StaticEnv()
+            .with("DATABRICKS_CONFIG_PROFILE", "__settings__")
+            .with("HOME", TestOSUtils.resource("/testdata/default_profile"));
+    DatabricksConfig config = createConfigWithMockClient();
+
+    DatabricksException ex =
+        assertThrows(
+            DatabricksException.class,
+            () -> {
+              resolveConfig(config, env);
+              config.authenticate();
+            });
+    assertTrue(
+        ex.getMessage().contains("has no __settings__ profile configured"),
+        "Error should reject __settings__ as a profile target: " + ex.getMessage());
+  }
+
   /** Test 7: default_profile pointing to nonexistent section */
   @Test
   public void testDefaultProfileNonexistentSection() {