fix(glue-alpha): prefix validation logic is incorrect (#27472)

There was logic in `aws-glue-alpha.Job` that expected `SparkUIProps.prefix` to be specified in the form `/prefix-name`, instead of the more conventional `prefix-name/`. This fix addresses the validation and handling of this prefix field to support the correct format. 


BREAKING CHANGE: `SparkUIProps.prefix` strings in the original `/prefix-name` format will now result in a validation error. To retain the same behavior, prefixes must be changed to the new `prefix-name/` format.

Closes #27396.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-glue-alpha/lib/job.ts

@@ -384,13 +384,13 @@ export interface SparkUIProps {
   /**
    * The bucket where the Glue job stores the logs.
    *
-   * @default a new bucket will be created.
+   * @default - a new bucket will be created.
    */
   readonly bucket?: s3.IBucket;
 
   /**
    * The path inside the bucket (objects prefix) where the Glue job stores the logs.
-   * Use format `'/foo/bar'`
+   * Use format `'foo/bar/'`
    *
    * @default - the logs will be written at the root of the bucket
    */
@@ -406,13 +406,15 @@ export interface SparkUIProps {
 export interface SparkUILoggingLocation {
   /**
    * The bucket where the Glue job stores the logs.
+   *
+   * @default - a new bucket will be created.
    */
   readonly bucket: s3.IBucket;
 
   /**
    * The path inside the bucket (objects prefix) where the Glue job stores the logs.
    *
-   * @default '/' - the logs will be written at the root of the bucket
+   * @default - the logs will be written at the root of the bucket
    */
   readonly prefix?: string;
 }
@@ -840,12 +842,12 @@ export class Job extends JobBase {
 
     const errors: string[] = [];
 
-    if (!prefix.startsWith('/')) {
-      errors.push('Prefix must begin with \'/\'');
+    if (prefix.startsWith('/')) {
+      errors.push('Prefix must not begin with \'/\'');
     }
 
-    if (prefix.endsWith('/')) {
-      errors.push('Prefix must not end with \'/\'');
+    if (!prefix.endsWith('/')) {
+      errors.push('Prefix must end with \'/\'');
     }
 
     if (errors.length > 0) {
@@ -854,7 +856,7 @@ export class Job extends JobBase {
   }
 
   private cleanPrefixForGrant(prefix?: string): string | undefined {
-    return prefix !== undefined ? prefix.slice(1) + '/*' : undefined;
+    return prefix !== undefined ? `${prefix}*` : undefined;
   }
 
   private setupContinuousLogging(role: iam.IRole, props: ContinuousLoggingProps) {

packages/@aws-cdk/aws-glue-alpha/test/job.test.ts

@@ -632,14 +632,14 @@ describe('Job', () => {
       });
       describe('with bucket and path provided', () => {
         const sparkUIBucketName = 'sparkbucketname';
-        const prefix = '/foob/bart';
-        const badPrefix = 'foob/bart/';
+        const prefix = 'foob/bart/';
+        const badPrefix = '/foob/bart';
         let sparkUIBucket: s3.IBucket;
 
         const expectedErrors = [
           `Invalid prefix format (value: ${badPrefix})`,
-          'Prefix must begin with \'/\'',
-          'Prefix must not end with \'/\'',
+          'Prefix must not begin with \'/\'',
+          'Prefix must end with \'/\'',
         ].join(EOL);
         it('fails if path is mis-formatted', () => {
           expect(() => new glue.Job(stack, 'BadPrefixJob', {
@@ -699,7 +699,7 @@ describe('Job', () => {
                         [
                           'arn:',
                           { Ref: 'AWS::Partition' },
-                          `:s3:::sparkbucketname${prefix}/*`,
+                          `:s3:::sparkbucketname/${prefix}*`,
                         ],
                       ],
                     },
@@ -718,7 +718,7 @@ describe('Job', () => {
           Template.fromStack(stack).hasResourceProperties('AWS::Glue::Job', {
             DefaultArguments: {
               '--enable-spark-ui': 'true',
-              '--spark-event-logs-path': `s3://${sparkUIBucketName}${prefix}`,
+              '--spark-event-logs-path': `s3://${sparkUIBucketName}/${prefix}`,
             },
           });
         });