fix(cloudfront): make long function name deterministic

packages/aws-cdk-lib/aws-cloudfront/lib/function.ts

@@ -224,7 +224,12 @@ export class Function extends Resource implements IFunction {
   private generateName(): string {
     const name = Stack.of(this).region + Names.uniqueId(this);
     if (name.length > 64) {
-      return name.substring(0, 32) + name.substring(name.length - 32);
+      if (name.startsWith('${Token[AWS.Region.') && name.indexOf('}') == 21) {
+        // Ensure consistency when region number is one digit or two
+        return name.substring(0, 31) + name.substring(name.length - 32);
+      } else {
+        return name.substring(0, 32) + name.substring(name.length - 32);
+      }
     }
     return name;
   }

packages/aws-cdk-lib/aws-cloudfront/test/function.test.ts

@@ -204,6 +204,29 @@ describe('CloudFront Function', () => {
     });
   });
 
+  test('long name truncates correctly every time', () => {
+    const app = new App();
+    const stack = new Stack(app, 'CdkTestWithALongNameStack');
+
+    new Function(stack, 'MyCloudFrontFunction', {
+      code: FunctionCode.fromInline('')
+    });
+
+    Template.fromStack(stack).hasResourceProperties('AWS::CloudFront::Function', {
+      'Name': {
+        'Fn::Join': [
+          '',
+          [
+            {
+              'Ref': 'AWS::Region'
+            },
+            'CdkTestWitackMyCloudFrontFunction302260D0'
+          ]
+        ]
+      }
+    });
+  })
+
   describe('key value store association', () => {
     test('minimal example', () => {
       const stack = new Stack();