chore: use absolute paths for mounts

Author: eoinsha

src/bundling.ts

@@ -154,7 +154,7 @@ export class Bundling {
       runtime: props.runtime.name,
       architecture: props.architecture ?? Architecture.ARM_64,
       buildArgs: props.buildArgs,
-      rootDir: props.rootDir,
+      rootDir: path.resolve(props.rootDir),
     };
 
     this.containerBuilderKey = `uv-bundling-${hash(hashableProperties)}`;
@@ -167,6 +167,7 @@ export class Bundling {
   private ensureBuilderReady(cdkOutDir: string) {
     const buildImage = this.createDockerImage();
     const hostUvBuildDir = path.join(cdkOutDir, this.containerBuilderKey);
+    const hostRootDir = path.resolve(this.props.rootDir);
 
     mkdirSync(hostUvBuildDir, { recursive: true });
 
@@ -182,7 +183,7 @@ export class Bundling {
       '-v',
       `${hostUvBuildDir}:/uvbuild`,
       '-v',
-      `${this.props.rootDir}:/src:ro`,
+      `${hostRootDir}:/src:ro`,
       buildImage.image,
     ];
 
@@ -289,7 +290,7 @@ function getCdkOutDir() {
   if (!cdkOutDir) {
     throw new Error('CDK_OUTDIR must be set before bundling Lambda assets');
   }
-  return cdkOutDir;
+  return path.resolve(cdkOutDir);
 }
 
 function sanitizeOutputComponent(value: string) {

test/function.test.ts

@@ -183,6 +183,41 @@ test(
   TEST_TIMEOUT,
 );
 
+test(
+  'Create a function when rootDir and CDK_OUTDIR are relative paths',
+  async () => {
+    const relativeRootDir = path.relative(
+      process.cwd(),
+      path.join(resourcesPath, 'basic_app'),
+    );
+    const relativeOutDir = path.relative(
+      process.cwd(),
+      process.env.CDK_OUTDIR as string,
+    );
+
+    process.env.CDK_OUTDIR = relativeOutDir;
+    const { app, stack } = await createStack('relative-paths');
+
+    new PythonFunction(stack, 'basic_app_relative', {
+      rootDir: relativeRootDir,
+      index: 'handler.py',
+      handler: 'lambda_handler',
+      runtime: Runtime.PYTHON_3_12,
+      architecture: await getDockerHostArch(),
+    });
+
+    const template = Template.fromStack(stack);
+    const functions = Object.values(
+      template.findResources('AWS::Lambda::Function'),
+    );
+
+    expect(functions).toHaveLength(1);
+    const contents = await getFunctionAssetContents(functions[0], app);
+    expect(contents).toContain('handler.py');
+  },
+  TEST_TIMEOUT,
+);
+
 test('Reuse one builder container for compatible functions', async () => {
   const { stack } = await createStack('shared');
   const architecture = await getDockerHostArch();