aws · S-Saranya1 · Aug 19, 2026 · Aug 12, 2026 · Aug 12, 2026 · Aug 12, 2026
@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "AWS SDK for Java v2",
+    "contributor": "",
+    "description": "Enable compiled endpoint rules for all services by default, with a fix for region parameter handling in the generated endpoint providers."
+}
@@ -315,9 +315,9 @@ public class CustomizationConfig {
     private boolean s3ExpressAuthSupport;
 
     /**
-     * Set to true to enable compiled endpoint rules. Currently defaults to false.
+     * Set to true to enable compiled endpoint rules. Defaults to true.
      */
-    private boolean enableGenerateCompiledEndpointRules = false;
+    private boolean enableGenerateCompiledEndpointRules = true;
 
     /**
      * Customization related to auth scheme derived from endpoints.

@@ -147,6 +147,13 @@ private void addAccessorMethods(TypeSpec.Builder b) {
                                   .addJavadoc("Returns the region. The region parameter may be used with the $S auth scheme.",
                                               AwsV4AuthScheme.SCHEME_ID)
                                   .build());
+            b.addMethod(MethodSpec.methodBuilder("regionId")
+                                  .addModifiers(Modifier.PUBLIC, Modifier.DEFAULT)
+                                  .returns(String.class)
+                                  .addJavadoc("Returns the region ID as a string. Returns null if region is not set.")
+                                  .addStatement("$T region = region()", Region.class)
+                                  .addStatement("return region == null ? null : region.id()")
+                                  .build());
         }
 
         if (authSchemeSpecUtils.hasSigV4aSupport()) {

@@ -187,6 +187,13 @@ private void addFieldsAndAccessors(TypeSpec.Builder b) {
                                   .returns(Region.class)
                                   .addStatement("return region")
                                   .build());
+
+            b.addMethod(MethodSpec.methodBuilder("regionId")
+                                  .addModifiers(Modifier.PUBLIC)
+                                  .addAnnotation(Override.class)
+                                  .returns(String.class)
+                                  .addStatement("return region == null ? null : region.id()")
+                                  .build());
         }
 
         if (authSchemeSpecUtils.hasSigV4aSupport()) {

@@ -25,9 +25,11 @@
 import javax.lang.model.element.Modifier;
 import software.amazon.awssdk.annotations.SdkPublicApi;
 import software.amazon.awssdk.codegen.model.intermediate.IntermediateModel;
+import software.amazon.awssdk.codegen.model.rules.endpoints.BuiltInParameter;
 import software.amazon.awssdk.codegen.model.rules.endpoints.ParameterModel;
 import software.amazon.awssdk.codegen.poet.ClassSpec;
 import software.amazon.awssdk.codegen.poet.PoetUtils;
+import software.amazon.awssdk.regions.Region;
 import software.amazon.awssdk.utils.builder.CopyableBuilder;
 import software.amazon.awssdk.utils.builder.ToCopyableBuilder;
 
@@ -56,6 +58,9 @@ public TypeSpec poetSpec() {
         parameters().forEach((name, model) -> {
             b.addField(endpointRulesSpecUtils.parameterClassField(name, model));
             b.addMethod(endpointRulesSpecUtils.parameterClassAccessorMethod(name, model));
+            if (model.getBuiltInEnum() == BuiltInParameter.AWS_REGION) {
+                b.addMethod(regionIdAccessorMethod(name));
+            }
         });
 
         b.addMethod(toBuilderMethod());
@@ -156,6 +161,22 @@ private String variableName(String name) {
         return intermediateModel.getNamingStrategy().getVariableName(name);
     }
 
+    /**
+     * Creates a convenience accessor for Region-typed parameters that returns the region ID as a String.
+     */
+    private MethodSpec regionIdAccessorMethod(String name) {
+        String varName = variableName(name);
+        String methodName = endpointRulesSpecUtils.paramMethodName(name) + "Id";
+        return MethodSpec.methodBuilder(methodName)
+                         .addModifiers(Modifier.PUBLIC)
+                         .addJavadoc("Returns the region ID (the {@link $T#id()} value) as a String,"
+                                     + " or null if region is not set.",
+                                     Region.class)
+                         .returns(String.class)
+                         .addStatement("return $N == null ? null : $N.id()", varName, varName)
+                         .build();
+    }
+
     private MethodSpec.Builder toBuilderConstructor() {
         MethodSpec.Builder constructorBuilder = MethodSpec.constructorBuilder();
         constructorBuilder.addModifiers(Modifier.PRIVATE);

@@ -253,6 +253,10 @@ public List<String> rulesEngineResourceFiles() {
     }
 
     public List<String> rulesEngineFilesFromDirectory(URL location) {
+        return rulesEngineFilesFromDirectory(location, RULES_ENGINE_RESOURCE_FILES_PREFIX);
+    }
+
+    public List<String> rulesEngineFilesFromDirectory(URL location, String prefix) {
         URI locationUri;
         try {
             locationUri = location.toURI();
@@ -268,7 +272,7 @@ public List<String> rulesEngineFilesFromDirectory(URL location) {
             return Files.walk(directory)
                         // Remove the root directory if the classes, paths are expected to be relative to this directory
                         .map(f -> directory.relativize(f).toString())
-                        .filter(f -> f.startsWith(RULES_ENGINE_RESOURCE_FILES_PREFIX))
+                        .filter(f -> f.startsWith(prefix))
                         .collect(Collectors.toList());
         } catch (IOException e) {
             throw new UncheckedIOException(e);
@@ -277,6 +281,12 @@ public List<String> rulesEngineFilesFromDirectory(URL location) {
 
     public List<String> rulesEngineResourceFiles2() {
         URL currentJarUrl = EndpointRulesSpecUtils.class.getProtectionDomain().getCodeSource().getLocation();
+
+        // This would happen if the classes aren't loaded from a JAR, e.g. when unit testing
+        if (!currentJarUrl.toString().endsWith(".jar")) {
+            return rulesEngineFilesFromDirectory(currentJarUrl, "software/amazon/awssdk/codegen/rules2/");
+        }
+
         try (JarFile jarFile = new JarFile(currentJarUrl.getFile())) {
             return jarFile.stream()
                           .map(ZipEntry::getName)

@@ -64,10 +64,6 @@ public RuleSetExpression root() {
         return root;
     }
 
-    public String regionParamName() {
-        return symbolTable.regionParamName();
-    }
-
     public SymbolTable symbolTable() {
         return symbolTable;
     }

@@ -40,7 +40,6 @@
 import software.amazon.awssdk.codegen.poet.PoetUtils;
 import software.amazon.awssdk.codegen.poet.rules.EndpointRulesSpecUtils;
 import software.amazon.awssdk.core.exception.SdkClientException;
-import software.amazon.awssdk.regions.Region;
 import software.amazon.awssdk.utils.CompletableFutureUtils;
 import software.amazon.awssdk.utils.Validate;
 
@@ -94,11 +93,7 @@ private static SymbolTable initSymbolTable(Map<String, ParameterModel> parameter
         parameters.forEach((k, v) -> {
             builder.putParam(k, fromParameterModel(v));
             if (v.getBuiltInEnum() == BuiltInParameter.AWS_REGION) {
-                // Region is a special case since it's already public API and uses an actual `Region` instance instead of
-                // `String`. We then introduce here a local with the same name but with String type such that we don't have
-                // to do the conversion everywhere a string represented region is used.
-                builder.regionParamName(k);
-                builder.putLocal(k, RuleRuntimeTypeMirror.STRING);
+                builder.addRegionParam(k);
             }
         });
         return builder.build();
@@ -150,14 +145,7 @@ private MethodSpec resolveEndpointMethod() {
 
         builder.addCode(validateRequiredParams());
         builder.beginControlFlow("try");
-        String regionParamName = utils.regionParamName();
-        if (regionParamName != null) {
-            builder.addStatement("$T region = params.$L()", Region.class, regionParamName);
-            builder.addStatement("$T regionId = region == null ? null : region.id()", String.class);
-            builder.addStatement("$T result = $L(params, regionId)", ruleResult(), utils.root().ruleId());
-        } else {
-            builder.addStatement("$T result = $L(params)", ruleResult(), utils.root().ruleId());
-        }
+        builder.addStatement("$T result = $L(params)", ruleResult(), utils.root().ruleId());
         builder.beginControlFlow("if (result.canContinue())")
                .addStatement("throw $T.create($S)", SdkClientException.class, "Rule engine did not reach an error or "
                                                                               + "endpoint result")

@@ -35,9 +35,9 @@ public RenameForCodegenVisitor(SymbolTable symbolTable) {
      * Returns the new symbol table with the renamed symbols.
      */
     public SymbolTable symbolTable() {
-        String regionParamName = symbolTable.regionParamName();
-        if (regionParamName != null) {
-            renames.regionParamName(javaName(regionParamName));
+        // Carry over region params with their renamed java names
+        for (String regionParam : symbolTable.regionParams()) {
+            renames.addRegionParam(javaName(regionParam));
         }
         return renames.build();
     }
@@ -58,11 +58,14 @@ public RuleExpression visitVariableReferenceExpression(VariableReferenceExpressi
             RuleType type = symbolTable.paramType(name);
             String newName = javaName(name);
             renames.putParam(newName, type);
+            // Region params return a Region object in Java but the rules use it as a String.
+            // Access the "{name}Id" method which returns the region ID as a String (null-safe).
+            String accessorName = symbolTable.isRegionParam(name) ? newName + "Id" : newName;
             return MemberAccessExpression
                 .builder()
                 .type(e.type())
                 .source(VariableReferenceExpression.builder().variableName("params").build())
-                .name(newName)
+                .name(accessorName)
                 .build();
         }
         return e;

@@ -16,19 +16,21 @@
 package software.amazon.awssdk.codegen.poet.rules2;
 
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.Set;
 import software.amazon.awssdk.utils.Validate;
 
 public final class SymbolTable {
     private final Map<String, RuleType> params;
     private final Map<String, RuleType> locals;
-    private final String regionParamName;
+    private final Set<String> regionParams;
 
     SymbolTable(Builder builder) {
         this.params = Collections.unmodifiableMap(new LinkedHashMap<>(builder.params));
         this.locals = Collections.unmodifiableMap(new LinkedHashMap<>(builder.locals));
-        this.regionParamName = builder.regionParamName;
+        this.regionParams = Collections.unmodifiableSet(new HashSet<>(builder.regionParams));
     }
 
     public static Builder builder() {
@@ -59,8 +61,20 @@ public Map<String, RuleType> params() {
         return params;
     }
 
-    public String regionParamName() {
-        return regionParamName;
+    /**
+     * Returns the set of parameter names that are Region-typed in Java (i.e., the Java getter returns {@code Region}
+     * rather than {@code String}). The codegen needs to append {@code .id()} when accessing these params to convert
+     * to the String value expected by the endpoint rules.
+     */
+    public Set<String> regionParams() {
+        return regionParams;
+    }
+
+    /**
+     * Returns true if the given parameter name is a Region-typed param that needs {@code .id()} appended.
+     */
+    public boolean isRegionParam(String name) {
+        return regionParams.contains(name);
     }
 
     public Builder toBuilder() {
@@ -70,15 +84,15 @@ public Builder toBuilder() {
     public static class Builder {
         private final Map<String, RuleType> params = new LinkedHashMap<>();
         private final Map<String, RuleType> locals = new LinkedHashMap<>();
-        private String regionParamName;
+        private final Set<String> regionParams = new HashSet<>();
 
         public Builder() {
         }
 
         public Builder(SymbolTable table) {
             this.params.putAll(table.params);
             this.locals.putAll(table.locals);
-            this.regionParamName = table.regionParamName;
+            this.regionParams.addAll(table.regionParams);
         }
 
         public Builder putParam(String name, RuleType type) {
@@ -99,8 +113,8 @@ public RuleType local(String name) {
             return locals.get(name);
         }
 
-        public Builder regionParamName(String regionParamName) {
-            this.regionParamName = regionParamName;
+        public Builder addRegionParam(String name) {
+            regionParams.add(Validate.paramNotNull(name, "name"));
             return this;
         }
 

@@ -36,6 +36,11 @@ public Region region() {
         return region;
     }
 
+    @Override
+    public String regionId() {
+        return region == null ? null : region.id();
+    }
+
     @Override
     public RegionSet regionSet() {
         return regionSet;

@@ -31,6 +31,14 @@ static Builder builder() {
      */
     Region region();
 
+    /**
+     * Returns the region ID as a string. Returns null if region is not set.
+     */
+    default String regionId() {
+        Region region = region();
+        return region == null ? null : region.id();
+    }
+
     /**
      * Returns the RegionSet. The regionSet parameter may be used with the "aws.auth#sigv4a" auth scheme.
      */

@@ -47,6 +47,11 @@ public Region region() {
         return region;
     }
 
+    @Override
+    public String regionId() {
+        return region == null ? null : region.id();
+    }
+
     @Override
     public QueryAuthSchemeParams.Builder toBuilder() {
         return new Builder(this);

@@ -45,6 +45,14 @@ static Builder builder() {
      */
     Region region();
 
+    /**
+     * Returns the region ID as a string. Returns null if region is not set.
+     */
+    default String regionId() {
+        Region region = region();
+        return region == null ? null : region.id();
+    }
+
     /**
      * Returns a {@link Builder} to customize the parameters.
      */

@@ -73,6 +73,11 @@ public Region region() {
         return region;
     }
 
+    @Override
+    public String regionId() {
+        return region == null ? null : region.id();
+    }
+
     @Override
     public RegionSet regionSet() {
         return regionSet;

@@ -81,6 +81,11 @@ public Region region() {
         return region;
     }
 
+    @Override
+    public String regionId() {
+        return region == null ? null : region.id();
+    }
+
     @Override
     public RegionSet regionSet() {
         return regionSet;

@@ -66,6 +66,14 @@ static Builder fromEndpointParams(QueryEndpointParams endpointParams) {
      */
     Region region();
 
+    /**
+     * Returns the region ID as a string. Returns null if region is not set.
+     */
+    default String regionId() {
+        Region region = region();
+        return region == null ? null : region.id();
+    }
+
     /**
      * Returns the RegionSet. The regionSet parameter may be used with the "aws.auth#sigv4a" auth scheme.
      */

@@ -59,6 +59,14 @@ static Builder fromEndpointParams(QueryEndpointParams endpointParams) {
      */
     Region region();
 
+    /**
+     * Returns the region ID as a string. Returns null if region is not set.
+     */
+    default String regionId() {
+        Region region = region();
+        return region == null ? null : region.id();
+    }
+
     /**
      * Returns the RegionSet. The regionSet parameter may be used with the "aws.auth#sigv4a" auth scheme.
      */

@@ -73,6 +73,13 @@ public Region region() {
         return region;
     }
 
+    /**
+     * Returns the region ID (the {@link Region#id()} value) as a String, or null if region is not set.
+     */
+    public String regionId() {
+        return region == null ? null : region.id();
+    }
+
     public Boolean useDualStackEndpoint() {
         return useDualStackEndpoint;
     }