build_system_requirements()

Warning

This feature is experimental and subject to breaking changes. See the Conan stability section for more information.

The build_system_requirements() method is a companion to system_requirements() intended specifically for system packages that are only needed when building from source (i.e., when the package binary is being compiled). It is not called when a pre-built binary is retrieved from a server or cache.

The key difference from system_requirements() is that build_system_requirements() installs packages using the build machine architecture (settings_build.arch) rather than the host architecture. This is especially important in cross-compilation scenarios where the build and host machines have different architectures.

Then, these requirements are intended to be “tools”, executables used at build time, but not libraries that would be linked in the consumers libraries or applications.

from conan import ConanFile
from conan.tools.system.package_manager import Apt

class MyPkg(ConanFile):
    name = "mypkg"
    version = "1.0"
    settings = "os", "arch"

    def build_system_requirements(self):
        # Installed using build machine arch (settings_build.arch),
        # only when building from source
        apt = Apt(self)
        apt.install(["build-essential", "pkg-config"])

    def system_requirements(self):
        # Installed using host arch (settings.arch), always
        apt = Apt(self)
        apt.install(["libssl-dev"])

Note

build_system_requirements() is only invoked when the package is being built from source. If the binary is already available in the cache or a remote, this method is skipped.