Manifest-Mode does not use Binary-Cache filled by a preceeding manual call of "vcpkg install".

[RealLitb]

I build a Docker-Container and want to prefill the Binary-Cache, such that when the container is used to build a repository in Manifest mode, and the manifest and compiler has not changed, the cached artifacts will be used.

However, when we use this Docker container according to the manual, the cache is not used and the packages are rebuilt. Is there any way I can tell VCPKG to tell me why a Cache-Miss happened? Or dump me the cache's content, so that I can maybe spot the different compiler flags or whatever is causing the Cache-Misses? I suspect a change in compiler flags, because the CCache also grows during the second build, indicating that possibly something with the compiler flags changed.

I created VCPKG's working tree using

# VCPKG
ARG VCPKG_ROOT=/opt/vcpkg
ENV VCPKG_ROOT=${VCPKG_ROOT}
ENV VCPKG_DEFAULT_BINARY_CACHE=/vcpkg-bincache
RUN mkdir -p $VCPKG_ROOT $VCPKG_DEFAULT_BINARY_CACHE 

RUN git clone https://github.com/microsoft/vcpkg $VCPKG_ROOT && cd $VCPKG_ROOT \
  && git checkout 2023.04.15 \
  && ./bootstrap-vcpkg.sh -disableMetrics

This just checks out the package to /opt/vcpkg, and then prebuilds the packages:

# Build all package, so that the bin cache is prepopulated when the repo build starts!
RUN mkdir -p /tmp/vcpkg-installed 
WORKDIR /tmp/vcpkg-installed
ADD vcpkg.json .
RUN $VCPKG_ROOT/vcpkg install --host-triplet=x64-linux-dynamic --triplet=x64-mingw-dynamic

That install happens at the very end of the docker image creation. Nothing is changed about compilers anymore afterwards. This is my CMakePresets:

    {
      "name": "debug@mingw",
      "displayName": "Debug Mingw",
      "generator": "Ninja",
      "binaryDir": "${sourceDir}/.out/build/debug-mingw",
      "cacheVariables": {
        "CMAKE_BUILD_TYPE": "Debug",
        "CMAKE_EXPORT_COMPILE_COMMANDS": true,
        "Boost_NO_WARN_NEW_VERSIONS": true,
        
        "CMAKE_SYSTEM_PROCESSOR": "x86_64",
        "VCPKG_CHAINLOAD_TOOLCHAIN_FILE": "$env{VCPKG_ROOT}/scripts/toolchains/mingw.cmake",
        "VCPKG_TARGET_TRIPLET": "x64-mingw-dynamic",
        "VCPKG_HOST_TRIPLET": "x64-linux-dynamic"
      },
      "toolchainFile": "$env{VCPKG_ROOT}/scripts/buildsystems/vcpkg.cmake"
    },

And this is my manifest:

{
  "dependencies": [
    {
      "name": "qtbase",
      "default-features": false,
      "features": ["widgets", "gui", "png"]
    },
    "spdlog",
    "fmt",
    "boost-asio",
    {
      "name": "qtbase",
      "default-features": false,
      "host": true
    }
  ]
}

Is there any obvious mistake that I'm making?

[RealLitb]

I found the solution! I used the "vcpkg_abi_info.txt" files in the install folder's share directory and found that the ENV-variables are different. Precisely, the PATH variable differs!

I use Visual Studio Code's CMake Tools, and it has the following additional entry in PATH:

/vscode/vscode-server/bin/linux-x64/.../bin/remote-cli

I now set the PATH identical in both the CMakePresets and in the Dockerfile, and it now uses the binary cache as it should!