Is it possible to remove the openssl dependency? Trying to use reqwest in Firecracker (musl, built in a container)

[hfingler]

I'm trying to use reqwest from inside Firecracker and, when I add reqwest to it, if it's a relatively new version, I get a dependency hell. By using any version, which resolves to 0.8.5, I get a openssl dependency problem (output is below).

The thing is, Firecracker is built inside a container and with musl which makes things a little harder. Is it possible to remove this dependency, maybe use rustls instead? The solution I've found (sfackler/rust-openssl#980) talks about the vendored approach, but it didn't work for me, maybe I did something wrong.

I guess it would be possible to either modify the container image to install/compile openssl against musl, but I'd like not to change something that important.

Thanks

error: failed to run custom build command for `openssl-sys v0.9.49`
process didn't exit successfully: `/firecracker/build/cargo_target/debug/build/openssl-sys-f900db53e43d4cae/build-script-main` (exit code: 101)
--- stdout
cargo:rustc-cfg=const_fn
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
run pkg_config fail: "Cross compilation detected. Use PKG_CONFIG_ALLOW_CROSS=1 to override"

--- stderr
thread 'main' panicked at '

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 = 0.9.49

', /usr/local/rust/registry/src/git.luolix.top-1ecc6299db9ec823/openssl-sys-0.9.49/build/find_normal.rs:150:5
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

[seanmonstar]

Yes, you can disable the default features (which is just default-tls), and enable rustls-tls.

[mbhall88]

Yes, you can disable the default features (which is just default-tls), and enable rustls-tls.

Excuse me if I've missed it somewhere, but it would be greatly appreciated if this could be documented somewhere as removing OpenSSL dependency is probably a reasonably common use case.