Merge pull request #12511 from backstage/blam/symlinks-in-scaffolder

Treat Symlink files as binaries

.changeset/perfect-donuts-applaud.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-backend': patch
+---
+
+Don't resolve symlinks, treat them as binary files and copy them as-is

plugins/scaffolder-backend/src/lib/files/serializeDirectoryContents.test.ts

@@ -97,6 +97,52 @@ describe('serializeDirectoryContents', () => {
     ]);
   });
 
+  it('should ignore symlinked files', async () => {
+    mockFs({
+      root: {
+        'a.txt': 'some text',
+        sym: mockFs.symlink({
+          path: './a.txt',
+        }),
+      },
+    });
+
+    await expect(serializeDirectoryContents('root')).resolves.toEqual([
+      {
+        path: 'a.txt',
+        executable: false,
+        content: Buffer.from('some text', 'utf8'),
+      },
+    ]);
+  });
+
+  it('should ignore symlinked folder files', async () => {
+    mockFs({
+      root: {
+        'a.txt': 'some text',
+        linkme: {
+          'b.txt': 'lols',
+        },
+        sym: mockFs.symlink({
+          path: './linkme',
+        }),
+      },
+    });
+
+    await expect(serializeDirectoryContents('root')).resolves.toEqual([
+      {
+        path: 'a.txt',
+        executable: false,
+        content: Buffer.from('some text', 'utf8'),
+      },
+      {
+        path: 'linkme/b.txt',
+        executable: false,
+        content: Buffer.from('lols', 'utf8'),
+      },
+    ]);
+  });
+
   it('should ignore gitignored files', async () => {
     mockFs({
       root: {

plugins/scaffolder-backend/src/scaffolder/actions/builtin/fetch/template.test.ts

@@ -186,6 +186,10 @@ describe('fetch:template', () => {
               },
               '.${{ values.name }}': '${{ values.itemList | dump }}',
               'a-binary-file.png': aBinaryFile,
+              symlink: mockFs.symlink({
+                path: 'a-binary-file.png',
+              }),
+
               '{% if values.showDummyFile %}dummy-file.txt{% else %}{% endif %}':
                 'dummy file',
               '${{ "dummy-file2.txt" if values.showDummyFile else "" }}':
@@ -265,6 +269,17 @@ describe('fetch:template', () => {
             .then(fObj => fObj.mode),
         ).resolves.toEqual(parseInt('100755', 8));
       });
+      it('copies file symlinks as-is without processing them', async () => {
+        await expect(
+          fs
+            .lstat(`${workspacePath}/target/symlink`)
+            .then(i => i.isSymbolicLink()),
+        ).resolves.toBe(true);
+
+        await expect(
+          fs.realpath(`${workspacePath}/target/symlink`),
+        ).resolves.toBe(`${workspacePath}/target/a-binary-file.png`);
+      });
     });
 
     describe('copyWithoutRender', () => {

plugins/scaffolder-backend/src/scaffolder/actions/builtin/fetch/template.ts

@@ -229,10 +229,11 @@ export function createFetchTemplateAction(options: {
           await fs.ensureDir(outputPath);
         } else {
           const inputFilePath = resolveSafeChildPath(templateDir, location);
+          const stats = await fs.promises.lstat(inputFilePath);
 
-          if (await isBinaryFile(inputFilePath)) {
+          if (stats.isSymbolicLink() || (await isBinaryFile(inputFilePath))) {
             ctx.logger.info(
-              `Copying binary file ${location} to template output path.`,
+              `Copying file binary or symbolic link at ${location}, to template output path.`,
             );
             await fs.copy(inputFilePath, outputPath);
           } else {