add DESTDIR

Author: sugyan

Dockerfile

@@ -2,11 +2,13 @@
 FROM heroku/python
 
 # Install OpenCV by https://github.com/jayrambhia/Install-OpenCV
-RUN mkdir -p /tmp/opencv
+ENV DESTDIR /app/.heroku/opencv
+RUN mkdir -p $DESTDIR /tmp/opencv
 WORKDIR /tmp/opencv
 RUN git clone https://github.com/jayrambhia/Install-OpenCV
 WORKDIR Install-OpenCV/Ubuntu
 RUN sed -i 's/sudo //g' *.sh
+RUN sed -i 's/make install/make DESTDIR=$DESTDIR install/' opencv_install.sh
 RUN echo 'deb http://archive.ubuntu.com/ubuntu trusty multiverse' >> /etc/apt/sources.list
 RUN apt-get update
 RUN ./opencv_latest.sh