Issue cross-compiling with OpenSSL

[ouillie]

I'm trying to link my Rust binary with musl. Luckily, there's a great example for how to do so. Unfortunately, I have a transitive dependency on openssl-sys and I'm running into the error below.

It's easy to reproduce; just apply this diff and run bazel build //:hello_linux_x86_64_musl from the examples/musl_cross_compiling directory.

ERROR: /home/will/.cache/bazel/_bazel_will/64f081568c0960bb2e2bba3133d0bc86/external/rules_rust++crate+cu__openssl-sys-0.9.106/BUILD.bazel:77:19: Running Cargo build script openssl-sys failed: (Exit 1): runner failed: error executing CargoBuildScriptRun command (from target @@rules_rust++crate+cu__openssl-sys-0.9.106//:_bs) bazel-out/k8-opt-exec-ST-d57f47055a04/bin/external/rules_rust+/cargo/cargo_build_script_runner/runner ... (remaining 10 arguments skipped)

Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
Build script process failed with exit code 101
--stdout:
cargo:rustc-check-cfg=cfg(osslconf, values("OPENSSL_NO_OCB", "OPENSSL_NO_SM4", "OPENSSL_NO_SEED", "OPENSSL_NO_CHACHA", "OPENSSL_NO_CAST", "OPENSSL_NO_IDEA", "OPENSSL_NO_CAMELLIA", "OPENSSL_NO_RC4", "OPENSSL_NO_BF", "OPENSSL_NO_PSK", "OPENSSL_NO_DEPRECATED_3_0", "OPENSSL_NO_SCRYPT", "OPENSSL_NO_SM3", "OPENSSL_NO_RMD160", "OPENSSL_NO_EC2M", "OPENSSL_NO_OCSP", "OPENSSL_NO_CMS", "OPENSSL_NO_COMP", "OPENSSL_NO_SOCK", "OPENSSL_NO_STDIO", "OPENSSL_NO_EC", "OPENSSL_NO_SSL3_METHOD", "OPENSSL_NO_KRB5", "OPENSSL_NO_TLSEXT", "OPENSSL_NO_SRP", "OPENSSL_NO_RFC3779", "OPENSSL_NO_SHA", "OPENSSL_NO_NEXTPROTONEG", "OPENSSL_NO_ENGINE", "OPENSSL_NO_BUF_FREELISTS", "OPENSSL_NO_RC2"))
cargo:rustc-check-cfg=cfg(openssl)
cargo:rustc-check-cfg=cfg(libressl)
cargo:rustc-check-cfg=cfg(boringssl)
cargo:rustc-check-cfg=cfg(libressl250)
cargo:rustc-check-cfg=cfg(libressl251)
cargo:rustc-check-cfg=cfg(libressl252)
cargo:rustc-check-cfg=cfg(libressl261)
cargo:rustc-check-cfg=cfg(libressl270)
cargo:rustc-check-cfg=cfg(libressl271)
cargo:rustc-check-cfg=cfg(libressl273)
cargo:rustc-check-cfg=cfg(libressl280)
cargo:rustc-check-cfg=cfg(libressl281)
cargo:rustc-check-cfg=cfg(libressl291)
cargo:rustc-check-cfg=cfg(libressl310)
cargo:rustc-check-cfg=cfg(libressl321)
cargo:rustc-check-cfg=cfg(libressl332)
cargo:rustc-check-cfg=cfg(libressl340)
cargo:rustc-check-cfg=cfg(libressl350)
cargo:rustc-check-cfg=cfg(libressl360)
cargo:rustc-check-cfg=cfg(libressl361)
cargo:rustc-check-cfg=cfg(libressl370)
cargo:rustc-check-cfg=cfg(libressl380)
cargo:rustc-check-cfg=cfg(libressl381)
cargo:rustc-check-cfg=cfg(libressl382)
cargo:rustc-check-cfg=cfg(libressl390)
cargo:rustc-check-cfg=cfg(libressl400)
cargo:rustc-check-cfg=cfg(libressl410)
cargo:rustc-check-cfg=cfg(ossl101)
cargo:rustc-check-cfg=cfg(ossl102)
cargo:rustc-check-cfg=cfg(ossl102f)
cargo:rustc-check-cfg=cfg(ossl102h)
cargo:rustc-check-cfg=cfg(ossl110)
cargo:rustc-check-cfg=cfg(ossl110f)
cargo:rustc-check-cfg=cfg(ossl110g)
cargo:rustc-check-cfg=cfg(ossl110h)
cargo:rustc-check-cfg=cfg(ossl111)
cargo:rustc-check-cfg=cfg(ossl111b)
cargo:rustc-check-cfg=cfg(ossl111c)
cargo:rustc-check-cfg=cfg(ossl111d)
cargo:rustc-check-cfg=cfg(ossl300)
cargo:rustc-check-cfg=cfg(ossl310)
cargo:rustc-check-cfg=cfg(ossl320)
cargo:rustc-check-cfg=cfg(ossl330)
cargo:rustc-check-cfg=cfg(ossl340)
cargo:rerun-if-env-changed=X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_LIB_DIR
X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_LIB_DIR unset
cargo:rerun-if-env-changed=OPENSSL_LIB_DIR
OPENSSL_LIB_DIR unset
cargo:rerun-if-env-changed=X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_INCLUDE_DIR
X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_INCLUDE_DIR unset
cargo:rerun-if-env-changed=OPENSSL_INCLUDE_DIR
OPENSSL_INCLUDE_DIR unset
cargo:rerun-if-env-changed=X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_DIR
X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_DIR unset
cargo:rerun-if-env-changed=OPENSSL_DIR
OPENSSL_DIR unset
cargo:rerun-if-env-changed=OPENSSL_NO_PKG_CONFIG
cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS_x86_64-unknown-linux-musl
cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS_x86_64_unknown_linux_musl
cargo:rerun-if-env-changed=TARGET_PKG_CONFIG_ALLOW_CROSS
cargo:rerun-if-env-changed=PKG_CONFIG_ALLOW_CROSS
cargo:rerun-if-env-changed=PKG_CONFIG_x86_64-unknown-linux-musl
cargo:rerun-if-env-changed=PKG_CONFIG_x86_64_unknown_linux_musl
cargo:rerun-if-env-changed=TARGET_PKG_CONFIG
cargo:rerun-if-env-changed=PKG_CONFIG
cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-musl
cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_musl
cargo:rerun-if-env-changed=TARGET_PKG_CONFIG_SYSROOT_DIR
cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR


Could not find openssl via pkg-config:
pkg-config has not been configured to support cross-compilation.

Install a sysroot for the target platform and configure it via
PKG_CONFIG_SYSROOT_DIR and PKG_CONFIG_PATH, or install a
cross-compiling wrapper for pkg-config and set it via
PKG_CONFIG environment variable.

cargo:warning=Could not find directory of OpenSSL installation, and this `-sys` crate cannot proceed without this knowledge. If OpenSSL is installed and this crate had trouble finding it,  you can set the `OPENSSL_DIR` environment variable for the compilation process. See stderr section below for further information.

--stderr:


Could not find directory of OpenSSL installation, and this `-sys` crate cannot
proceed without this knowledge. If OpenSSL is installed and this crate had
trouble finding it,  you can set the `OPENSSL_DIR` environment variable for the
compilation process.

Make sure you also have the development packages of openssl installed.
For example, `libssl-dev` on Ubuntu or `openssl-devel` on Fedora.

If you're in a situation where you think the directory *should* be found
automatically, please open a bug at https://github.com/sfackler/rust-openssl
and include information about your system as well as this message.

$HOST = x86_64-unknown-linux-gnu
$TARGET = x86_64-unknown-linux-musl
openssl-sys = 0.0.0



Target //:hello_linux_x86_64_musl failed to build
Use --verbose_failures to see the command lines of failed build steps.
ERROR: /home/will/.cache/bazel/_bazel_will/64f081568c0960bb2e2bba3133d0bc86/external/rules_rust++crate+cu__openssl-sys-0.9.106/BUILD.bazel:27:13 Compiling Rust rlib openssl_sys v0.9.106 (68 files) failed: (Exit 1): runner failed: error executing CargoBuildScriptRun command (from target @@rules_rust++crate+cu__openssl-sys-0.9.106//:_bs) bazel-out/k8-opt-exec-ST-d57f47055a04/bin/external/rules_rust+/cargo/cargo_build_script_runner/runner ... (remaining 10 arguments skipped)

Thanks in advance for any possible clues!

[ouillie]

For the record, this seems to be a normal cross-compiling issue. I also attempted building from source and it causes this other error which seems to be more Bazel-specific (truncated for brevity):

...
cargo:warning=openssl-src: failed to build OpenSSL from source

--stderr:



/home/will/.cache/bazel/_bazel_will/64f081568c0960bb2e2bba3133d0bc86/sandbox/linux-sandbox/127/execroot/_main/external/rules_rust++crate+cu__openssl-src-300.4.2-3.4.1/openssl: No such file or directory (os error 2)
...

[ouillie]

Figured it out: https://github.com/ouillie/bazel-rust-musl

[illicitonion]

FWIW I published an openssl module to the Bazel Central Registry which is well-tested for cross-compilation, and uses cc_library rather than rules_foreign_cc :)