From 9b9bca369dd04943a7103241c6cb342859b6f43f Mon Sep 17 00:00:00 2001
From: Davide Melfi <dmelfi@amazon.com>
Date: Fri, 12 Jun 2026 15:51:59 +0100
Subject: [PATCH] fix: defaulting to process.cwd() when LAMBDA_TASK_ROOT is not
 found

---
 src/utils/runtime-setup.test.ts |  8 +++++---
 src/utils/runtime-setup.ts      | 10 ++++++----
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/utils/runtime-setup.test.ts b/src/utils/runtime-setup.test.ts
index 24b1a51..84a7c5c 100644
--- a/src/utils/runtime-setup.test.ts
+++ b/src/utils/runtime-setup.test.ts
@@ -68,13 +68,15 @@ describe("runtime-setup", () => {
       );
     });
 
-    it("should throw if LAMBDA_TASK_ROOT is not set", async () => {
+    it("should fall back to process.cwd() when LAMBDA_TASK_ROOT is not set", async () => {
       // GIVEN
       delete process.env.LAMBDA_TASK_ROOT;
 
       // WHEN & THEN
-      await expect(createRuntime()).rejects.toThrow(
-        "LAMBDA_TASK_ROOT environment variable is not set",
+      await createRuntime();
+      expect(UserFunctionLoader.load).toHaveBeenCalledWith(
+        process.cwd(),
+        expect.any(String),
       );
     });
   });
diff --git a/src/utils/runtime-setup.ts b/src/utils/runtime-setup.ts
index bf61cdf..6e9f54c 100644
--- a/src/utils/runtime-setup.ts
+++ b/src/utils/runtime-setup.ts
@@ -18,7 +18,12 @@ export async function createRuntime(
   const isMultiConcurrent = isMultiConcurrentMode();
   const runtimeApi = process.env.AWS_LAMBDA_RUNTIME_API;
   const handlerString = process.env._HANDLER;
-  const taskRoot = process.env.LAMBDA_TASK_ROOT;
+  // LAMBDA_TASK_ROOT is a restricted environment variable set to /var/task.
+  // If we set it as required we are forcing customers to set it to a value that
+  // can't change.
+  // We fall back to process.cwd() to allow OCI customers to place the handler wherever
+  // they want.
+  const taskRoot = process.env.LAMBDA_TASK_ROOT || process.cwd();
 
   if (!runtimeApi) {
     throw new PlatformError(
@@ -28,9 +33,6 @@ export async function createRuntime(
   if (!handlerString) {
     throw new PlatformError("_HANDLER environment variable is not set");
   }
-  if (!taskRoot) {
-    throw new PlatformError("LAMBDA_TASK_ROOT environment variable is not set");
-  }
 
   const rapidClient = await RAPIDClient.create(
     runtimeApi,