Python code hangs when importing openCV in AWS Nitro Enclave - linux

Question

I'm trying to do some image recognition inside the AWS nitro-enclave with python. But the code hangs when importing packages such as OpenCV, NumPy, and pandas. The dockerfile file used to build the enclave would function normally in my local machine or in EC2. The generated enclave console would output some openBLAS warning about L2 cache size and the process freezes. No error output of any sort.
Is there any additional dependencies I need to add when using packages in enclave or there are some conflicts with the kernel?
The docker, shell, and py test codes are shown below:
#amazonlinux still have the import issue
#python:3.7 libs importing crush
FROM amazonlinux
WORKDIR /app
#py 3.7
RUN yum install python3 zip -y
ENV VIRTIAL_ENV=/opt/venv
RUN python3 -m venv $VIRTIAL_ENV
ENV PATH="$VIRTIAL_ENV/bin:$PATH"
#3 libs needed for cv2 import
RUN yum install libSM-1.2.2-2.amzn2.x86_64 -y
RUN yum install libXrender-0.9.10-1.amzn2.x86_64 -y
RUN yum install libXext-1.3.3-3.amzn2.x86_64 -y
COPY requirements.txt ./
RUN pip3 install --no-cache-dir -r /app/requirements.txt
#shell script testing
COPY dockerfile_entrypoint.sh ./
COPY test_cv2.py ./
#ENV for shell testing printf loop
ENV HELLO="Hello from enclave side!"
RUN chmod +X dockerfile_entrypoint.sh
#shell script testing
CMD ["/app/dockerfile_entrypoint.sh"]
#!/bin/bash
#shell printf loop test in enclave
# go to work dir and check files
cd /app||return
ls
#cv2 imp issue
python3 test_cv2.py
#use shell loop to keep enclave live to see error message output
count=1
while true;do
printf "[%4d] $HELLO\n" $count
echo "$PWD"
ls
count=$((count+1))
sleep 5
done
import cv2
for i in range(10):
print('testing OpenCV')

Answer 1

These types of hangs can happen when applications or libraries attempt to read data from /dev/random but there is not sufficient entropy, which causes the process to block on the read. There are some possible solutions in this GitHub issue: https://github.com/aws/aws-nitro-enclaves-sdk-c/issues/41#issuecomment-792621500