fix(s3-assets): cannot publish a file without extension (#30597)

### Issue # (if applicable)

Closes #30471 

###

### Reason for this change
Publishing a file with no extension using the `Asset` class with `BundlingOutput.SINGLE_FILE` and `AssetHashType.SOURCE`(default), as shown below, will result in an error `fail: EISDIR: illegal operation on a directory, read`, and publishing will fail.
```ts
export class AssetTestStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
      super(scope, id, props);

      const asset = new s3assets.Asset(this, 'asset', {
          path: path.join(__dirname, '../assets/main'),
          bundling: {
              image: DockerImage.fromRegistry('golang:1.21'),
              entrypoint: ["bash", "-c"],
              command: ["echo 123 > /asset-output/main"], // a file without extension
              outputType: BundlingOutput.SINGLE_FILE,
          },
      });
      new CfnOutput(this, 'AssetHash', { value: asset.assetHash });
  }
}
```

This is because the path in `*.asset.json` is different from the actual file path.
The `*.asset.json` expects the file to be in `asset.bead5b2c0d128650228f146d2326d5f3cbfb36738a9383fc6a09b1e9278803f0`, but when I check the `cdk.out` directory, I see that `asset.bead5b2c0d128650228f146d2326d5f3cbfb36738a9383fc6a09b1e9278803f0` is a directory, not a file.
```json
{
  "version": "36.0.0",
  "files": {
    "bead5b2c0d128650228f146d2326d5f3cbfb36738a9383fc6a09b1e9278803f0": {
      "source": {
        "path": "asset.bead5b2c0d128650228f146d2326d5f3cbfb36738a9383fc6a09b1e9278803f0",
        "packaging": "file"
      },
      "destinations": {
        "current_account-us-east-1": {
          "bucketName": "cdk-hnb659fds-assets-${AWS::AccountId}-us-east-1",
          "objectKey": "bead5b2c0d128650228f146d2326d5f3cbfb36738a9383fc6a09b1e9278803f0.bead5b2c0d128650228f146d2326d5f3cbfb36738a9383fc6a09b1e9278803f0",
          "region": "us-east-1",
          "assumeRoleArn": "arn:${AWS::Partition}:iam::${AWS::AccountId}:role/cdk-hnb659fds-file-publishing-role-${AWS::AccountId}-us-east-1"
        }
      }
    }
}
```
```bash
cdk.out
├── SampleStack.assets.json
├── SampleStack.template.json
├── asset.bead5b2c0d128650228f146d2326d5f3cbfb36738a9383fc6a09b1e9278803f0
│   └── main
├── cdk.out
├── manifest.json
└── tree.json
```

If I change it to a file with an extension, as shown below, I see that the file with the extension is staged under `cdk.out` dir, and the asset is published successfully.
```ts
export class AssetTestStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
      super(scope, id, props);

      const asset = new s3assets.Asset(this, 'asset', {
          path: path.join(__dirname, '../assets/main'),
          bundling: {
              image: DockerImage.fromRegistry('golang:1.21'),
              entrypoint: ["bash", "-c"],
              command: ["echo 123 > /asset-output/main.bin"], // a file with an extension
              outputType: BundlingOutput.SINGLE_FILE,
          },
      });
      new CfnOutput(this, 'AssetHash', { value: asset.assetHash });
  }
}
```
```bash
cdk.out
├── SampleStack.assets.json
├── SampleStack.template.json
├── asset.dc5ce447844d7490834e46df016edc7f671b4fae19ab55b6c78973dcb5af98f8
│   └── main.bin
├── asset.dc5ce447844d7490834e46df016edc7f671b4fae19ab55b6c78973dcb5af98f8.bin # !! staged file here !!
├── cdk.out
├── manifest.json
└── tree.json
```
```json
{
  "version": "36.0.0",
  "files": {
    "dc5ce447844d7490834e46df016edc7f671b4fae19ab55b6c78973dcb5af98f8": {
      "source": {
        "path": "asset.dc5ce447844d7490834e46df016edc7f671b4fae19ab55b6c78973dcb5af98f8.bin",
        "packaging": "file"
      },
      "destinations": {
        "current_account-us-east-1": {
          "bucketName": "cdk-hnb659fds-assets-${AWS::AccountId}-us-east-1",
          "objectKey": "dc5ce447844d7490834e46df016edc7f671b4fae19ab55b6c78973dcb5af98f8.bin",
          "region": "us-east-1",
          "assumeRoleArn": "arn:${AWS::Partition}:iam::${AWS::AccountId}:role/cdk-hnb659fds-file-publishing-role-${AWS::AccountId}-us-east-1"
        }
      }
    }
}
```

Files without extensions must be staged correctly in order to be published correctly.

### Description of changes
The directory to write the bundling output is usually `cdk.out/asset.{asset hash}`.
If the extension exists, it will be renamed from `cdk.out/asset.{asset hash}/{asset file name}` to `cdk.out/{asset hash}.{asset file extension}`.
https://github.com/aws/aws-cdk/blob/c826d8faaeb310623eb9a1a1c82930b679768007/packages/aws-cdk-lib/core/lib/asset-staging.ts#L392

If the extension does not exist, the file name `cdk.out/asset.{asset hash}` (without extension) will be the same as the directory where bundling output is written.
Therefore, the file is already considered staged and will not be staged correctly.
https://github.com/aws/aws-cdk/blob/c826d8faaeb310623eb9a1a1c82930b679768007/packages/aws-cdk-lib/core/lib/asset-staging.ts#L383

Therefore, in such cases, I fix to change the file name by adding a suffix such as `noext` after the file name so that the file is correctly renamed.

### Description of how you validated changes
unit tests and integ test.


### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

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

packages/@aws-cdk-testing/framework-integ/test/aws-s3-assets/test/integ.assets.file-bundling.lit.ts

@@ -26,6 +26,17 @@ class TestStack extends Stack {
 
     const user = new iam.User(this, 'MyUser');
     asset.grantRead(user);
+
+    new assets.Asset(this, 'BundledAssetWithoutExtension', {
+      path: path.join(__dirname, 'markdown-asset'),
+      bundling: {
+        image: DockerImage.fromBuild(path.join(__dirname, 'alpine-markdown')),
+        outputType: BundlingOutput.SINGLE_FILE,
+        command: [
+          'sh', '-c', 'echo 123 > /asset-output/main',
+        ],
+      },
+    });
   }
 }
 

packages/aws-cdk-lib/core/lib/asset-staging.ts

@@ -278,9 +278,10 @@ export class AssetStaging extends Construct {
    */
   private stageByCopying(): StagedAsset {
     const assetHash = this.calculateHash(this.hashType);
-    const stagedPath = this.stagingDisabled
+    const targetPath = this.stagingDisabled
       ? this.sourcePath
       : path.resolve(this.assetOutdir, renderAssetFilename(assetHash, getExtension(this.sourcePath)));
+    const stagedPath = this.renderStagedPath(this.sourcePath, targetPath);
 
     if (!this.sourceStats.isDirectory() && !this.sourceStats.isFile()) {
       throw new Error(`Asset ${this.sourcePath} is expected to be either a directory or a regular file`);
@@ -338,7 +339,10 @@ export class AssetStaging extends Construct {
     // Calculate assetHash afterwards if we still must
     assetHash = assetHash ?? this.calculateHash(this.hashType, bundling, bundledAsset.path);
 
-    const stagedPath = path.resolve(this.assetOutdir, renderAssetFilename(assetHash, bundledAsset.extension));
+    const stagedPath = this.renderStagedPath(
+      bundledAsset.path,
+      path.resolve(this.assetOutdir, renderAssetFilename(assetHash, bundledAsset.extension)),
+    );
 
     this.stageAsset(bundledAsset.path, stagedPath, 'move');
 
@@ -388,7 +392,7 @@ export class AssetStaging extends Construct {
     }
 
     // Moving can be done quickly
-    if (style == 'move') {
+    if (style === 'move') {
       fs.renameSync(sourcePath, targetPath);
       return;
     }
@@ -511,6 +515,17 @@ export class AssetStaging extends Construct {
         throw new Error('Unknown asset hash type.');
     }
   }
+
+  private renderStagedPath(sourcePath: string, targetPath: string): string {
+    // Add a suffix to the asset file name
+    // because when a file without extension is specified, the source directory name is the same as the staged asset file name.
+    // But when the hashType is `AssetHashType.OUTPUT`, the source directory name begins with `bundling-temp-` and the staged asset file name is different.
+    // We only need to add a suffix when the hashType is not `AssetHashType.OUTPUT`.
+    if (this.hashType !== AssetHashType.OUTPUT && path.dirname(sourcePath) === targetPath) {
+      targetPath = targetPath + '_noext';
+    }
+    return targetPath;
+  }
 }
 
 function renderAssetFilename(assetHash: string, extension = '') {

packages/aws-cdk-lib/core/test/docker-stub-cp.sh

@@ -6,6 +6,17 @@ set -euo pipefail
 echo "$@" >> /tmp/docker-stub-cp.input.concat
 echo "$@" > /tmp/docker-stub-cp.input
 
+# create a file without extension to emulate created files, fetch the target path from the "docker cp" command
+if cat /tmp/docker-stub-cp.input.concat | grep "DOCKER_STUB_SINGLE_FILE_WITHOUT_EXT"; then
+  if echo "$@" | grep "cp"| grep "/asset-output"; then
+    outdir=$(echo "$@" | grep cp | grep "/asset-output" | xargs -n1 | grep "cdk.out" | head -n1 | cut -d":" -f1)
+    if [ -n  "$outdir" ]; then
+      touch "${outdir}/test" # create a file witout extension
+      exit 0
+    fi
+  fi
+fi
+
 # create a fake zip to emulate created files, fetch the target path from the "docker cp" command
 if echo "$@" | grep "cp"| grep "/asset-output"; then
   outdir=$(echo "$@" | grep cp | grep "/asset-output" | xargs -n1 | grep "cdk.out" | head -n1 | cut -d":" -f1)

packages/aws-cdk-lib/core/test/docker-stub.sh

@@ -37,6 +37,12 @@ if echo "$@" | grep "DOCKER_STUB_SINGLE_ARCHIVE"; then
   exit 0
 fi
 
+if echo "$@" | grep "DOCKER_STUB_SINGLE_FILE_WITHOUT_EXT"; then
+  outdir=$(echo "$@" | xargs -n1 | grep "/asset-output" | head -n1 | cut -d":" -f1)
+  touch ${outdir}/test # create a file witout extension
+  exit 0
+fi
+
 if echo "$@" | grep "DOCKER_STUB_SINGLE_FILE"; then
   outdir=$(echo "$@" | xargs -n1 | grep "/asset-output" | head -n1 | cut -d":" -f1)
   touch ${outdir}/test.txt

packages/aws-cdk-lib/core/test/staging.test.ts

@@ -20,6 +20,7 @@ enum DockerStubCommand {
   MULTIPLE_FILES = 'DOCKER_STUB_MULTIPLE_FILES',
   SINGLE_ARCHIVE = 'DOCKER_STUB_SINGLE_ARCHIVE',
   SINGLE_FILE = 'DOCKER_STUB_SINGLE_FILE',
+  SINGLE_FILE_WITHOUT_EXT = 'DOCKER_STUB_SINGLE_FILE_WITHOUT_EXT',
   VOLUME_SINGLE_ARCHIVE = 'DOCKER_STUB_VOLUME_SINGLE_ARCHIVE',
 }
 
@@ -1450,6 +1451,68 @@ describe('staging', () => {
     expect(staging.isArchive).toEqual(false);
   });
 
+  test('bundling that produces a single file with SINGLE_FILE_WITHOUT_EXT and hash type SOURCE', () => {
+    // GIVEN
+    const app = new App({ context: { [cxapi.NEW_STYLE_STACK_SYNTHESIS_CONTEXT]: false } });
+    const stack = new Stack(app, 'stack');
+    const directory = path.join(__dirname, 'fs', 'fixtures', 'test1');
+
+    // WHEN
+    const staging = new AssetStaging(stack, 'Asset', {
+      sourcePath: directory,
+      bundling: {
+        image: DockerImage.fromRegistry('alpine'),
+        command: [DockerStubCommand.SINGLE_FILE_WITHOUT_EXT],
+        outputType: BundlingOutput.SINGLE_FILE,
+      },
+      assetHashType: AssetHashType.SOURCE, // default
+    });
+
+    // THEN
+    const assembly = app.synth();
+    expect(fs.readdirSync(assembly.directory)).toEqual([
+      'asset.ef734136dc22840a94140575a2f98cbc061074e09535589d1cd2c11a4ac2fd75',
+      'asset.ef734136dc22840a94140575a2f98cbc061074e09535589d1cd2c11a4ac2fd75_noext',
+      'cdk.out',
+      'manifest.json',
+      'stack.template.json',
+      'tree.json',
+    ]);
+    expect(staging.packaging).toEqual(FileAssetPackaging.FILE);
+    expect(staging.isArchive).toEqual(false);
+  });
+
+  test('bundling that produces a single file with SINGLE_FILE_WITHOUT_EXT and hash type CUSTOM', () => {
+    // GIVEN
+    const app = new App({ context: { [cxapi.NEW_STYLE_STACK_SYNTHESIS_CONTEXT]: false } });
+    const stack = new Stack(app, 'stack');
+    const directory = path.join(__dirname, 'fs', 'fixtures', 'test1');
+
+    // WHEN
+    const staging = new AssetStaging(stack, 'Asset', {
+      sourcePath: directory,
+      bundling: {
+        image: DockerImage.fromRegistry('alpine'),
+        command: [DockerStubCommand.SINGLE_FILE_WITHOUT_EXT],
+        outputType: BundlingOutput.SINGLE_FILE,
+      },
+      assetHashType: AssetHashType.CUSTOM,
+      assetHash: 'custom',
+    });
+
+    // THEN
+    const assembly = app.synth();
+    expect(fs.readdirSync(assembly.directory)).toEqual([
+      'asset.f81c5ba9e81eebb202881a8e61a83ab4b69f6bee261989eb93625c9cf5d35335',
+      'asset.f81c5ba9e81eebb202881a8e61a83ab4b69f6bee261989eb93625c9cf5d35335_noext',
+      'cdk.out',
+      'manifest.json',
+      'stack.template.json',
+      'tree.json',
+    ]);
+    expect(staging.packaging).toEqual(FileAssetPackaging.FILE);
+    expect(staging.isArchive).toEqual(false);
+  });
 });
 
 describe('staging with docker cp', () => {
@@ -1517,6 +1580,71 @@ describe('staging with docker cp', () => {
       expect.stringContaining('volume rm assetOutput'),
     ]));
   });
+
+  test('bundling that produces a single file with docker image copy variant and hash type SOURCE', () => {
+    // GIVEN
+    const app = new App({ context: { [cxapi.NEW_STYLE_STACK_SYNTHESIS_CONTEXT]: false } });
+    const stack = new Stack(app, 'stack');
+    const directory = path.join(__dirname, 'fs', 'fixtures', 'test1');
+
+    // WHEN
+    const staging = new AssetStaging(stack, 'Asset', {
+      sourcePath: directory,
+      bundling: {
+        image: DockerImage.fromRegistry('alpine'),
+        command: [DockerStubCommand.SINGLE_FILE_WITHOUT_EXT],
+        outputType: BundlingOutput.SINGLE_FILE,
+        bundlingFileAccess: BundlingFileAccess.VOLUME_COPY,
+      },
+      assetHashType: AssetHashType.SOURCE, // default
+    });
+
+    // THEN
+    const assembly = app.synth();
+    expect(fs.readdirSync(assembly.directory)).toEqual([
+      'asset.93bd4079bff7440a725991ecf249416ae9ad73cb639f4a8d9e8f3ad8d491e89f',
+      'asset.93bd4079bff7440a725991ecf249416ae9ad73cb639f4a8d9e8f3ad8d491e89f_noext',
+      'cdk.out',
+      'manifest.json',
+      'stack.template.json',
+      'tree.json',
+    ]);
+    expect(staging.packaging).toEqual(FileAssetPackaging.FILE);
+    expect(staging.isArchive).toEqual(false);
+  });
+
+  test('bundling that produces a single file with docker image copy variant and hash type CUSTOM', () => {
+    // GIVEN
+    const app = new App({ context: { [cxapi.NEW_STYLE_STACK_SYNTHESIS_CONTEXT]: false } });
+    const stack = new Stack(app, 'stack');
+    const directory = path.join(__dirname, 'fs', 'fixtures', 'test1');
+
+    // WHEN
+    const staging = new AssetStaging(stack, 'Asset', {
+      sourcePath: directory,
+      bundling: {
+        image: DockerImage.fromRegistry('alpine'),
+        command: [DockerStubCommand.SINGLE_FILE_WITHOUT_EXT],
+        outputType: BundlingOutput.SINGLE_FILE,
+        bundlingFileAccess: BundlingFileAccess.VOLUME_COPY,
+      },
+      assetHashType: AssetHashType.CUSTOM,
+      assetHash: 'custom',
+    });
+
+    // THEN
+    const assembly = app.synth();
+    expect(fs.readdirSync(assembly.directory)).toEqual([
+      'asset.53a51b4c68874a8e831e24e8982120be2a608f50b2e05edb8501143b3305baa8',
+      'asset.53a51b4c68874a8e831e24e8982120be2a608f50b2e05edb8501143b3305baa8_noext',
+      'cdk.out',
+      'manifest.json',
+      'stack.template.json',
+      'tree.json',
+    ]);
+    expect(staging.packaging).toEqual(FileAssetPackaging.FILE);
+    expect(staging.isArchive).toEqual(false);
+  });
 });
 
 // Reads a docker stub and cleans the volume paths out of the stub.