Using two docker images at once - docker

Question

I have a following scenario. I want to use tensorflow for ML and OpenCV for some image processing. I recently learned about dockers and found out, that both TF and OCV are dockerized. I can easily pull the image and run eg. tensorflow script. Is there a way to somehow merge what both dockers offer? Or run on top of it. I want to write a piece of code that uses both OpenCV and Tensorflow. Is there a way to achieve this?
Or in more generic sense: Docker A image has preinstalled python package AA. Docker B has python package BB. How can I write script that uses functions from both AA and BB?

Answer 1

Really simple. Build your own docker image with both TF and OpenCV. Example Dockerfile (Based on janza/docker-python3-opencv):
FROM python:3.7
LABEL maintainet="John Doe"
RUN apt-get update && \
apt-get install -y \
build-essential \
cmake \
git \
wget \
unzip \
yasm \
pkg-config \
libswscale-dev \
libtbb2 \
libtbb-dev \
libjpeg-dev \
libpng-dev \
libtiff-dev \
libavformat-dev \
libpq-dev && \
pip install numpy && \
pip install tensorflow
WORKDIR /
ENV OPENCV_VERSION="3.4.2"
RUN wget https://github.com/opencv/opencv/archive/${OPENCV_VERSION}.zip \
&& unzip ${OPENCV_VERSION}.zip \
&& mkdir /opencv-${OPENCV_VERSION}/cmake_binary \
&& cd /opencv-${OPENCV_VERSION}/cmake_binary \
&& cmake -DBUILD_TIFF=ON \
-DBUILD_opencv_java=OFF \
-DWITH_CUDA=OFF \
-DWITH_OPENGL=ON \
-DWITH_OPENCL=ON \
-DWITH_IPP=ON \
-DWITH_TBB=ON \
-DWITH_EIGEN=ON \
-DWITH_V4L=ON \
-DBUILD_TESTS=OFF \
-DBUILD_PERF_TESTS=OFF \
-DCMAKE_BUILD_TYPE=RELEASE \
-DCMAKE_INSTALL_PREFIX=$(python3.7 -c "import sys; print(sys.prefix)") \
-DPYTHON_EXECUTABLE=$(which python3.7) \
-DPYTHON_INCLUDE_DIR=$(python3.7 -c "from distutils.sysconfig import get_python_inc; print(get_python_inc())") \
-DPYTHON_PACKAGES_PATH=$(python3.7 -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())") \
.. \
&& make install \
&& rm /${OPENCV_VERSION}.zip \
&& rm -r /opencv-${OPENCV_VERSION}
Of course, I don't know your exact requirements regarding this project and there is some probability that this Dockerfile won't work for you. Just adjust it to you needs. But I recommend creating from ground zero (just basing on some already existing image of some Linux distribution). Then you have full control what have you installed in which versions without redundant stuff that is often found in 3rd party images (I'm not saying they are bad, but often for people use cases most parts are redundant.)
There is also already combined docker image in official hub:
https://hub.docker.com/r/fbcotter/docker-tensorflow-opencv/
If you reaaaaly want to have it separate I guess you could link running containers of those images. Containers for the linked service are reachable at a hostname identical to the alias, or the service name if no alias was specified. But you would have to implement some kind of logic to use another package from another container (probably possible but difficult and complex).
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