ImportError: libGL.so.1: cannot open shared object file: No such file or directory

Add the following lines to your Dockerfile:

RUN apt-get update
RUN apt-get install ffmpeg libsm6 libxext6  -y

These commands install the cv2 dependencies that are normally present on the local machine, but might be missing in your Docker container causing the issue.

Even though the above solutions work. But their package sizes are quite big. libGL.so.1 is provided by package libgl1. So the following code is sufficient.

apt-get update && apt-get install libgl1

This is a little bit better solution in my opinion. Package python3-opencv includes all system dependencies of OpenCV.

RUN apt-get update && apt-get install -y python3-opencv
RUN pip install opencv-python

Try installing opencv-python-headless python dependency instead of opencv-python. That includes a precompiled binary wheel with no external dependencies (other than numpy), and is intended for headless environments like Docker. This saved almost 700mb in my docker image compared with using the python3-opencv Debian package (with all its dependencies).

The package documentation discusses this and the related (more expansive) opencv-contrib-python-headless pypi package.

Example reproducing the ImportError in the question

# docker run -it python:3.9-slim bash -c "pip -q install opencv-python; python -c 'import cv2'"
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python3.9/site-packages/cv2/__init__.py", line 5, in <module>
    from .cv2 import *
ImportError: libGL.so.1: cannot open shared object file: No such file or directory
# docker run -it python:3.9-slim bash -c "pip -q install opencv-python-headless; python -c 'import cv2'"
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv

For me, the only WA that worked is following:

# These are for libGL.so issues
# RUN apt-get update
# RUN apt install libgl1-mesa-glx
# RUN apt-get install -y python3-opencv
# RUN pip3 install opencv-python
RUN pip3 install opencv-python-headless==4.5.3.56

If you're on CentOS, RHEL, Fedora, or other linux distros that use yum, you'll want:

sudo yum install mesa-libGL -y

Put this in the Dockerfile

RUN apt-get update
RUN apt install -y libgl1-mesa-glx

Before the line

COPY requirements.txt requirements.txt

For example

......

RUN apt-get update
RUN apt install -y libgl1-mesa-glx

COPY requirements.txt requirements.txt

......

In my case it was enough to do the following which also saves space in comparison to above solutions

RUN apt-get update && apt-get install -y --no-install-recommends \
        libgl1 \
        libglib2.0-0 \

I was getting the same error when I was trying to use OpenCV in the GCP Appengine Flex server environment. Replacing "opencv-python" by "opencv-python-headless" in the requirements.txt solved the problem.

The OpenCV documentation talks about different packages for desktop vs. Server (headless) environments.

I met this problem while using cv2 in a docker container. I fixed it by:

pip install opencv-contrib-python

install opencv-contrib-python rather than opencv-python.

had the same issue on centos 8 after using pip3 install opencv on a non gui server which is lacking all sorts of graphics libraries.

dnf install opencv

pulls in all needed dependencies.

For a raspberry pi, put this , work for me :

sudo apt-get install ffmpeg libsm6 libxext6  -y

For me, the problem was related to proxy setting. For pypi, I was using nexus mirror to pypi, for opencv nothing worked. Until I connected to a different network.

Here is the solution you need:

pip install -U opencv-python
apt-get upgrade
apt update && apt install -y libsm6 libxext6 ffmpeg libfontconfig1 libxrender1 libgl1-mesa-glx