VCPKG_KEEP_ENV_VARS only works on Linux

[ASxa86]

Hello,

I'm trying to use a custom triplet that defines ANDROID_SDK_ROOT using my system's environment ANDROID_HOME. To do this, I define some cmake preset configuration like so:

{
    "version": 6,
    "configurePresets": [
        {
            "name": "target-arm64-android",
            "hidden": true,
            "cacheVariables": {
                "VCPKG_CHAINLOAD_TOOLCHAIN_FILE": "${sourceDir}/vcpkg/scripts/toolchains/android.cmake",
                "VCPKG_TARGET_TRIPLET": "arm64-android-aspire",
                "VCPKG_INSTALL_OPTIONS": "--allow-unsupported;--debug-env",
                "VCPKG_KEEP_ENV_VARS": "ANDROID_HOME;ANDROID_NDK_HOME",
                "ANDROID_STL": "c++_shared",
                "ANDROID_SDK_ROOT": "$env{ANDROID_HOME}",
                "ANDROID_PLATFORM": "34",
                "ANDROID_ABI": "arm64-v8a"
            }
        }
    ]
}

Triplet:

set(VCPKG_TARGET_ARCHITECTURE arm64)
set(VCPKG_CRT_LINKAGE dynamic)
set(VCPKG_LIBRARY_LINKAGE static)
set(VCPKG_CMAKE_SYSTEM_NAME Android)
set(VCPKG_MAKE_BUILD_TRIPLET "--host=aarch64-linux-android")
set(VCPKG_CMAKE_CONFIGURE_OPTIONS -DANDROID_ABI=arm64-v8a)
set(VCPKG_BUILD_TYPE release)

# Only use Qt as shared libraries.
if(${PORT} MATCHES "qt")
    set(VCPKG_LIBRARY_LINKAGE dynamic)
endif()

message(STATUS "ANDROID_HOME: $ENV{ANDROID_HOME}")

# Qt requires that the ANDROID_SDK_ROOT is defined when compiling.
set(ANDROID_SDK_ROOT "$ENV{ANDROID_HOME}")
set(ANDROID_PLATFORM 34)

The preset in combination with the triplet enables me to cross-compile Qt libraries using arm64 android on Linux or Windows.

The line, "VCPKG_KEEP_ENV_VARS": "ANDROID_HOME;ANDROID_NDK_HOME" is what makes this possible. Unfortunately, on Windows, this doesn't seem to work. My environment variables are not getting passed through to vcpkg. Additionally, I get the cmake warning that VCPKG_KEEP_ENV_VARS is not being used.

The actual command that vcpkg runs with cmake looks something like the following (you can see where VCPKG_KEEP_ENV_VARS attempts to be defined):

d:\dev\aspire/vcpkg/downloads/tools/cmake-3.29.2-windows/cmake-3.29.2-windows-i386/bin/cmake -DVCPKG_HOST_TRIPLET=x64-windows-aspire -DVCPKG_CHAINLOAD_TOOLCHAIN_FILE=D:/dev/aspire/vcpkg/scripts/toolchains/android.cmake -DVCPKG_TARGET_TRIPLET=arm64-android-aspire -DVCPKG_INSTALL_OPTIONS="--allow-unsupported;--debug-env" -DVCPKG_KEEP_ENV_VARS="ANDROID_HOME;ANDROID_NDK_HOME" -DVCPKG_ENV_PASSTHROUGH="ANDROID_HOME;ANDROID_NDK_HOME" -DANDROID_STL=c++_shared -DANDROID_SDK_ROOT=C:/Qt/android/sdk -DANDROID_PLATFORM=34 -DANDROID_ABI=arm64-v8a -DCMAKE_BUILD_TYPE=Debug -DCMAKE_CXX_COMPILER=cl -DCMAKE_C_COMPILER=cl -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DCMAKE_COMPILE_WARNING_AS_ERROR=ON -DCMAKE_TOOLCHAIN_FILE=D:/dev/aspire/vcpkg/scripts/buildsystems/vcpkg.cmake -SD:/dev/aspire -BD:/dev/aspire/build

I'm wondering if I'm missing something? I can access the environment variables from my own cmake files but I can't seem to access them from the triplet.

Any thoughts or suggestions for me to try?

[ASxa86]

If it helps others in the future. While I don't know why this worked on Linux. The official vcpkg documentation states VCPKG_KEEP_ENV_VARS is to be defined as an environment variable.

Therefore, the solution is to use the environment key to define the values instead of the cacheVariables.

{
    "version": 6,
    "configurePresets": [
        {
            "name": "target-arm64-android",
            "hidden": true,
            "cacheVariables": {
                "VCPKG_CHAINLOAD_TOOLCHAIN_FILE": "${sourceDir}/vcpkg/scripts/toolchains/android.cmake",
                "VCPKG_TARGET_TRIPLET": "arm64-android-aspire",
                "VCPKG_INSTALL_OPTIONS": "--allow-unsupported;--debug-env",
                "ANDROID_STL": "c++_shared",
                "ANDROID_SDK_ROOT": "$env{ANDROID_HOME}",
                "ANDROID_PLATFORM": "34",
                "ANDROID_ABI": "arm64-v8a"
            },
            "environment": {
                "VCPKG_KEEP_ENV_VARS": "ANDROID_HOME;ANDROID_NDK_HOME"
             }
        }
    ]
}

[dg0yt]

I don't know why this worked on Linux.

It doesn't. It has no effect on Linux.

The official vcpkg documentation states VCPKG_KEEP_ENV_VARS is to be defined as an environment variable.

There are triplet variables VCPKG_ENV_PASSTHROUGH and VCPKG_ENV_PASSTHROUGH_UNTRACKED,
https://learn.microsoft.com/en-us/vcpkg/users/triplets#vcpkg_env_passthrough
And there is also the explanation: These variables change a behavior of the vcpkg tool which is active only on Windows.

[ASxa86]

Thank you for the information!

For what it's worth, I do have a pipeline running with Android sdk installed in a docker container that was using my previous config and it worked just fine. I also have a vscode devcontainer that also worked. Which is why I was struggling with this.
I didn't have to define the VCPKG_KEEP_ENV_VARS environment variable on Linux but defining it as a cmake variable would enable me to use my environment variables in my triplets.