add chmod u+s /usr/bin/sudo

Dockerfile

@@ -38,6 +38,7 @@ RUN adduser --disabled-password --gecos '' --shell /bin/bash user \
  && chown -R user:user /app
 RUN usermod -aG sudo user
 RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers
+RUN chmod u+s /usr/bin/sudo
 ### RUN echo "user ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/90-user
 USER user