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rustmusl

How to build an executable that depends on curl for x86_64-unknown-linux-musl

I am on an amd64 Debian machine, and am trying to build a x86_64-unknown-linux-musl executable. I have this in my Cargo.toml:

[dependencies]
curl = "0.4"

When I run cargo build --target=x86_64-unknown-linux-musl I get this:

error: failed to run custom build command for `libz-sys v1.0.10`
process didn't exit successfully: `/tmp/foo/target/debug/build/libz-sys-c20da5f29c41e515/build-script-build` (exit code: 101)
--- stdout
OPT_LEVEL = Some("0")
PROFILE = Some("debug")
TARGET = Some("x86_64-unknown-linux-musl")
debug=true opt-level=0
HOST = Some("x86_64-unknown-linux-gnu")
TARGET = Some("x86_64-unknown-linux-musl")
TARGET = Some("x86_64-unknown-linux-musl")
HOST = Some("x86_64-unknown-linux-gnu")
CC_x86_64-unknown-linux-musl = None
CC_x86_64_unknown_linux_musl = None
TARGET_CC = None
CC = None
HOST = Some("x86_64-unknown-linux-gnu")
CROSS_COMPILE = None
TARGET = Some("x86_64-unknown-linux-musl")
HOST = Some("x86_64-unknown-linux-gnu")
CFLAGS_x86_64-unknown-linux-musl = None
CFLAGS_x86_64_unknown_linux_musl = None
TARGET_CFLAGS = None
CFLAGS = None
running: "./configure" "--prefix=/tmp/foo/target/x86_64-unknown-linux-musl/debug/build/libz-sys-e109627694e9981e/out"
Compiler error reporting is too harsh for ./configure (perhaps remove -Werror).
** ./configure aborting.

--- stderr
thread 'main' panicked at 'failed to run successfully: exit code: 1', /home/tshepang/.cargo/registry/src/github.com-1ecc6299db9ec823/libz-sys-1.0.10/build.rs:189

When I re-run it:

error: failed to run custom build command for `openssl-sys v0.9.6`
process didn't exit successfully: `/tmp/foo/target/debug/build/openssl-sys-ac9c042b062dad1d/build-script-build` (exit code: 101)
--- 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.

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 = 0.9.6

All works well when I build natively, i.e. cargo build --target=x86_64-unknown-linux-gnu.

Searching around, I learned about an environment variable, PKG_CONFIG_ALLOW_CROSS:

PKG_CONFIG_ALLOW_CROSS=true cargo build --target=x86_64-unknown-linux-musl

In doing that, I also found that I was missing the Debian package named libcurl4-openssl-dev.

Running ldd target/target/x86_64-unknown-linux-musl/debug/foo indicated the executable is dynamically linked, then searching further, I learned about another environment variable, PKG_CONFIG_ALL_STATIC:

PKG_CONFIG_ALL_STATIC=true PKG_CONFIG_ALLOW_CROSS=true cargo build --target=x86_64-unknown-linux-musl

That revealed a whole bunch of missing deps, all of which (luckily) had Debian dependencies. But installing all of them did not help, as, in the end, I was still sitting with an executable that wasn't statically linked .

Solution

  • I gave in and ended up using cross:

    cargo install cross
cross build --target=x86_64-unknown-linux-musl

    This was just too easy, and you will find the executable in target/x86_64-unknown-linux-musl/debug.