Dockerfile

########## Build arguments ##########
ARG OPENCV_VERSION=5.0.0

########## Build OpenCV ##########
FROM ubuntu:resolute AS opencv-builder

ARG OPENCV_VERSION
ENV DEBIAN_FRONTEND=noninteractive
ENV OPENCV_VERSION=${OPENCV_VERSION}
ENV CCACHE_DIR=/root/.ccache
ENV CCACHE_MAXSIZE=2G

WORKDIR /

# Install build and OpenCV dependencies (with BuildKit cache for apt)
RUN --mount=type=cache,target=/var/cache/apt \
    --mount=type=cache,target=/var/lib/apt/lists \
    set -eux; \
    apt-get -o Acquire::Retries=3 update; \
    apt-get -y install --no-install-recommends \
      apt-transport-https \
      software-properties-common \
      wget \
      unzip \
      ca-certificates \
      build-essential \
      cmake \
      git \
      ccache \
      libtbb-dev \
      libopenblas-dev \
      liblapacke-dev \
      libgtk-3-dev \
      libavcodec-dev \
      libavformat-dev \
      libswscale-dev \
      libdc1394-dev \
      libxine2-dev \
      libv4l-dev \
      libtheora-dev \
      libvorbis-dev \
      libxvidcore-dev \
      libopencore-amrnb-dev \
      libopencore-amrwb-dev \
      x264 \
      libtesseract-dev \
      libgdiplus \
      pkg-config \
      libavutil-dev \
      ninja-build

# Copy cmake options (needed before OpenCV configure)
COPY cmake/opencv_build_options.cmake /opencv_build_options.cmake

# Fetch OpenCV and opencv_contrib sources
RUN set -eux; \
    wget -q https://github.com/opencv/opencv/archive/${OPENCV_VERSION}.zip; \
    unzip -q ${OPENCV_VERSION}.zip; \
    rm ${OPENCV_VERSION}.zip; \
    mv opencv-${OPENCV_VERSION} /opencv; \
    wget -q https://github.com/opencv/opencv_contrib/archive/${OPENCV_VERSION}.zip; \
    unzip -q ${OPENCV_VERSION}.zip; \
    rm ${OPENCV_VERSION}.zip; \
    mv opencv_contrib-${OPENCV_VERSION} /opencv_contrib

# Configure, build, and install OpenCV with ccache and parallel build
#
# -D CMAKE_ASM_COMPILER="": disables the ASM language so OpenCV 5's vendored
# MLAS turns off and DNN falls back to its built-in SGEMM. The MLAS FP16/GQA
# path references MlasHGemmSupported(), which OpenCV 5.0.0 declares and calls
# but never defines, breaking the extern link with an undefined reference
# (same fix as windows.yml / linux-arm64.yml / macos.yml).
RUN --mount=type=cache,target=/root/.ccache \
    set -eux; \
    cmake -G Ninja \
      -C /opencv_build_options.cmake \
      -S /opencv -B /opencv/build \
      -D OPENCV_EXTRA_MODULES_PATH=/opencv_contrib/modules \
      -D CMAKE_BUILD_TYPE=RELEASE \
      -D CMAKE_C_COMPILER_LAUNCHER=ccache \
      -D CMAKE_CXX_COMPILER_LAUNCHER=ccache \
      -D CMAKE_INSTALL_PREFIX=/opencv_artifacts \
      -D CMAKE_ASM_COMPILER=""; \
    cmake --build /opencv/build --parallel "$(nproc)"; \
    cmake --install /opencv/build; \
    ldconfig

########## Build OpenCvSharp native extern ##########
FROM opencv-builder AS opencvsharp-builder

# Copy local OpenCvSharp sources
COPY src/ /opencvsharp/src/

# Build and install OpenCvSharp native extern with ccache
RUN --mount=type=cache,target=/root/.ccache \
    set -eux; \
    mkdir -p /opencvsharp/make; \
    cmake -G Ninja \
      -S /opencvsharp/src -B /opencvsharp/make \
      -D CMAKE_INSTALL_PREFIX=/opencvsharp/make \
      -D CMAKE_C_COMPILER_LAUNCHER=ccache \
      -D CMAKE_CXX_COMPILER_LAUNCHER=ccache \
      -D CMAKE_PREFIX_PATH=/opencv_artifacts; \
    cmake --build /opencvsharp/make --parallel "$(nproc)"; \
    cmake --install /opencvsharp/make; \
    rm -rf /opencv /opencv_contrib; \
    cp /opencvsharp/make/OpenCvSharpExtern/libOpenCvSharpExtern.so /usr/lib/; \
    mkdir -p /artifacts; \
    cp /opencvsharp/make/OpenCvSharpExtern/libOpenCvSharpExtern.so /artifacts/

########## Test native .so file ##########
FROM mcr.microsoft.com/dotnet/sdk:10.0-noble AS test-native
# libopenblas0/liblapacke: runtime deps of libOpenCvSharpExtern.so (linked against
# OpenBLAS/LAPACKE in the opencv-builder stage). Installed fresh here (rather than
# relying on the /usr/lib copy below) because the update-alternatives symlinks that
# make libopenblas.so.0 resolvable live outside /usr/lib and would otherwise be lost.
RUN apt-get update && apt-get -y install --no-install-recommends gcc libopenblas0 liblapacke && rm -rf /var/lib/apt/lists/*
# OpenBLAS's own pthread-based internal thread pool crashes (SIGABRT) when called
# concurrently from OpenCV's own parallel_for_ (e.g. stitching's BestOf2NearestMatcher
# matches image pairs on multiple threads, each hitting LAPACK/SVD). Force OpenBLAS to
# stay single-threaded internally; OpenCV's own parallelism is unaffected.
ENV OPENBLAS_NUM_THREADS=1
COPY --from=opencvsharp-builder /usr/lib /usr/lib
RUN echo "\n\
#include <stdio.h> \n\
int core_Mat_sizeof(); \n\
int main(){ \n\
  int i = core_Mat_sizeof(); \n\
  printf(\"sizeof(Mat) = %d\", i); \n\
  return 0; \n\
}" > /test.c && \
    gcc -I./ -L./ test.c -o test -lOpenCvSharpExtern && \
    LD_LIBRARY_PATH=. ./test

########## Test .NET class libraries ##########
FROM mcr.microsoft.com/dotnet/sdk:10.0-noble AS test-dotnet
# See test-native above for why these are installed fresh instead of relying on
# the /usr/lib copy. clang/zlib1g-dev are link-time dependencies of PublishAot's ILCompiler
# (used by the NativeAOT smoke test further below) - installed here, in the same apt-get pass as
# everything else, rather than in a second `apt-get update` after the test run below: a second
# pass hit a reproducible `apt-get` segfault (`libapt-private.so.0.0: no version information
# available` followed by SIGSEGV) in this same container stage, immediately after the 1700+ tests
# above it had run. Root cause unconfirmed, but installing everything up front sidesteps it.
RUN apt-get update && apt-get -y install --no-install-recommends libopenblas0 liblapacke clang zlib1g-dev && rm -rf /var/lib/apt/lists/*
# See test-native above: keep OpenBLAS single-threaded to avoid crashing when called
# from OpenCV's own parallel_for_ (e.g. stitching's BestOf2NearestMatcher).
ENV OPENBLAS_NUM_THREADS=1
COPY --from=opencvsharp-builder /usr/lib /usr/lib
COPY global.json /opencvsharp/global.json
COPY src/ /opencvsharp/src/
COPY test/ /opencvsharp/test/
WORKDIR /opencvsharp
RUN cd /opencvsharp/src/OpenCvSharp && \
    dotnet build -c Release -f net8.0 && \
    cd /opencvsharp/src/OpenCvSharp.GdipExtensions && \
    dotnet build -c Release -f net8.0
RUN dotnet test --project /opencvsharp/test/OpenCvSharp.Tests/OpenCvSharp.Tests.csproj -c Release -f net10.0 --runtime linux-x64 --results-directory /opencvsharp/test/OpenCvSharp.Tests/TestResults --report-xunit-trx --report-xunit-trx-filename test-results.trx < /dev/null

# Restore and publish as separate steps: see windows.yml's "Test NativeAOT publish" step for why
# a combined restore+publish invocation fails restore with NETSDK1207 (NuGet's static graph
# restore doesn't honor the OpenCvSharp.Analyzers ProjectReference's UndefineProperties the way
# an actual build does). libOpenCvSharpExtern.so resolves via /usr/lib's default linker search
# path (COPY'd there above), so no LD_LIBRARY_PATH is needed to run the published exe.
RUN cd /opencvsharp/test/OpenCvSharp.Tests.NativeAot && \
    dotnet restore -r linux-x64 && \
    dotnet publish -c Release -f net10.0 --runtime linux-x64 -p:PublishAot=true --no-restore && \
    ./bin/Release/net10.0/linux-x64/publish/OpenCvSharp.Tests.NativeAot

########## Final images ##########
FROM mcr.microsoft.com/dotnet/sdk:10.0-noble AS final-sdk
# See test-native above for why these are installed fresh instead of relying on
# the /usr/lib copy.
RUN apt-get update && apt-get -y install --no-install-recommends libopenblas0 liblapacke && rm -rf /var/lib/apt/lists/*
# See test-native above: keep OpenBLAS single-threaded to avoid crashing when called
# from OpenCV's own parallel_for_ (e.g. stitching's BestOf2NearestMatcher).
ENV OPENBLAS_NUM_THREADS=1
COPY --from=opencvsharp-builder /usr/lib /usr/lib
COPY --from=opencvsharp-builder /artifacts /artifacts

FROM mcr.microsoft.com/dotnet/aspnet:10.0-noble AS final
RUN apt-get update && apt-get -y install --no-install-recommends libopenblas0 liblapacke && rm -rf /var/lib/apt/lists/*
# See test-native above: keep OpenBLAS single-threaded to avoid crashing when called
# from OpenCV's own parallel_for_ (e.g. stitching's BestOf2NearestMatcher).
ENV OPENBLAS_NUM_THREADS=1
COPY --from=opencvsharp-builder /usr/lib /usr/lib
COPY --from=opencvsharp-builder /artifacts /artifacts