Some more debugging. Added aws-lambda-adapter just in case that's useful in AWS Lambda

Dockerfile

@@ -20,6 +20,9 @@ COPY lambda_entrypoint.py .
 # Stage 2: Final runtime image
 FROM public.ecr.aws/docker/library/python:3.11.9-slim-bookworm
 
+# Install Lambda web adapter in case you want to run with with an AWS Lamba function URL (not essential if not using Lambda)
+COPY --from=public.ecr.aws/awsguru/aws-lambda-adapter:0.8.4 /lambda-adapter /opt/extensions/lambda-adapter
+
 # Install system dependencies. Need to specify -y for poppler to get it to install
 RUN apt-get update \
     && apt-get install -y \

entrypoint_router.py

@@ -1,5 +1,4 @@
 import os
-import subprocess
 
 if __name__ == "__main__":
     run_direct_mode = os.getenv("RUN_DIRECT_MODE", "0")

lambda_entrypoint.py

@@ -4,11 +4,14 @@ import subprocess
 
 print("In lambda_entrypoint function")
 
-s3_client = boto3.client("s3")
-
-print("s3_client is:", s3_client
-      )
-TMP_DIR = "/tmp"  # Use absolute path
+try:
+    s3_client = boto3.client("s3", region_name="eu-west-2")
+    print("s3_client is initialized:", s3_client)
+except Exception as e:
+    print(f"Error initializing s3_client: {e}")
+    raise e
+
+TMP_DIR = "/tmp/"
 
 def download_file_from_s3(bucket_name, key, download_path):
     """Download a file from S3 to the local filesystem."""