Linker in second Docker layer doesn't find shared OpenCV libraries built in previous layer, but files exist

问题

I'm trying to create a docker image with OpenCV 4.3 and my own C++ program linked against OpenCV, both built for Linux. Because building OpenCV takes quite a while and the resulting docker image is pretty large and I only need libopencv_core.so and libopencv_calib3d.so, I tried to create the following two layers:

Build OpenCV from source and build my own C++ program that links against OpenCV
Copy the shared OpenCV libraries and my compiled program created in the first build layer to the second layer and execute my program

Unfortunately, the linker outputs

error while loading shared libraries: libopencv_core.so.4.3: cannot open shared object file: No such file or directory

Adding

RUN ls /usr/local/lib

in the second layer just before the command to execute my program shows that I successfully copied the built library files:

libopencv_calib3d.so
libopencv_calib3d.so.4.3
libopencv_calib3d.so.4.3.0
libopencv_core.so
libopencv_core.so.4.3
libopencv_core.so.4.3.0

I already tried these statements to make the libraries visible:

RUN ldconfig /usr/local/lib
RUN export LD_LIBRARY_PATH="/lib:/usr/lib:/usr/local/lib"
RUN ldconfig -v

where ldconfig -v prints (among other things):

/usr/local/lib:
libopencv_calib3d.so.4.3 -> libopencv_calib3d.so.4.3.0
libopencv_core.so.4.3 -> libopencv_core.so.4.3.0

I was a bit confused because ldconfig didn't list libopencv_calib3d.so, that's why I tried create a simlink manually but it complained that libopencv_calib3d.so already exists. So it seems that everything is there to run my program. Any suggestions what I am doing wrong?

Appendix

This is the Dockerfile that I'm using (reduced to the important parts):

FROM vookimedlo/ubuntu-clang:clang_bionic AS builder

# Install dependencies
RUN apt-get update & ...

ARG libPath=/usr/local/lib

# Install OpenCV
RUN git clone & cmake & make install
    tar -czvf ${libPath}/opencv.tar.gz /usr/local/lib/libopencv_calib3d.so /usr/local/lib/libopencv_calib3d.so.4.* /usr/local/lib/libopencv_core.so /usr/local/lib/libopencv_core.so.4.*

# Download and build my program
...

FROM ubuntu AS runtime

ARG libPath=/usr/local/lib

# Copy compiled libraries
COPY --from=builder ${libPath}/opencv.tar.gz ${libPath}/opencv.tar.gz
RUN tar -xvf ${libPath}/opencv.tar.gz -C / && rm ${libPath}/opencv.tar.gz

# Copy my program
...

RUN ldconfig /usr/local/lib
RUN export LD_LIBRARY_PATH="/lib:/usr/lib:/usr/local/lib"
RUN ldconfig -v

# Run my program
CMD ...

回答1:

In OPs post they mention using .so.4.* This will not get the .so.4 file, only the .so.4. files. I suspect what is happening is a .so -> .so.4 -> so.4-> .so.4.3 -> .so.4.3.0 link chain is missing a link.

To solve this the following lines:

# Install OpenCV
RUN git clone & cmake & make install
    tar -czvf ${libPath}/opencv.tar.gz /usr/local/lib/libopencv_calib3d.so /usr/local/lib/libopencv_calib3d.so.4.* /usr/local/lib/libopencv_core.so /usr/local/lib/libopencv_core.so.4.*

Should be updated to:

# Install OpenCV
RUN git clone & cmake & make install
    tar -czvf ${libPath}/opencv.tar.gz \
             /usr/local/lib/libopencv_calib3d.so* \ 
             /usr/local/lib/libopencv_core.so*

(Line breaks and \ only added to make it easier to read for some)

A long list of ls -l /usr/local/lib/libopencv_* from the generated system to confirm.

来源：https://stackoverflow.com/questions/61001290/linker-in-second-docker-layer-doesnt-find-shared-opencv-libraries-built-in-prev

标签

c++

Linux

Docker

shared-libraries