Если вы решили использовать в своем проекте то, что нужнается в Openssl — будьте готовы что можете столкнуться с кучей ошибок при сборке, особенно если собираете под стандартную реализацию libc в musl.

При сборке cargo вам вывалит что -то подобное:

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
  run pkg_config fail: 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.

  --- stderr
  thread 'main' panicked at /home/.cargo/registry/src/index.crates.io-6f17d22bba15001f/openssl-sys-0.9.102/build/find_normal.rs:190:5:


  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 = 0.9.102

У меня такая фигня пошла, когда я решил добавить Sentry в свой проект.

Решение следующее:

Выполняем команды:

sudo apt-get update
sudo apt-get install -y musl-dev musl-tools linux-headers-$(uname -r)

sudo ln -s /usr/include/x86_64-linux-gnu/asm /usr/include/x86_64-linux-musl/asm && ln -s /usr/include/asm-generic /usr/include/x86_64-linux-musl/asm-generic && ln -s /usr/include/linux /usr/include/x86_64-linux-musl/linux
sudo mkdir /musl
wget https://github.com/openssl/openssl/archive/OpenSSL_1_1_1f.tar.gz
tar zxf OpenSSL_1_1_1f.tar.gz 
cd openssl-OpenSSL_1_1_1f/
CC="musl-gcc -fPIE -pie -static -idirafter /usr/include/ -idirafter /usr/include/x86_64-linux-gnu/" ./Configure no-shared no-async --prefix=/musl --openssldir=/musl/ssl linux-x86_64
make depend
make -j$(nproc)
sudo make install

Экспортируем переменные окружения:
export PKG_CONFIG_ALLOW_CROSS=1
export OPENSSL_STATIC=true
export OPENSSL_DIR=/musl

Пробуем выполнять сборку:
cargo build --release --target=x86_64-unknown-linux-musl