Example for using cross from x86_64 to arm64 for a package using libssl-dev ?

[shadiakiki1986]

The package I'm trying to cross-compile depends on libssl-dev.

I'm trying to cross-compile it to arm64 to benefit from some cost reductions on aws t4g.nano instances,
but I couldn't get it to work.

My thoughts were that I'd need a custom docker image as follows

FROM rustembedded/cross:aarch64-unknown-linux-gnu-0.2.1
RUN dpkg --add-architecture arm64 && \
    apt-get update && \
    apt-get install --assume-yes libssl-dev pkg-config

whereby I would've thought that I should use libssl-dev:arm64 in the above, but that doesn't exist, eg by running:

docker run rustembedded/cross:aarch64-unknown-linux-gnu-0.2.1 dpkg --add-architecture arm64 &&     sudo apt-get update &&     sudo apt-cache search libssl-dev:arm64

with the output at https://pastebin.com/7Q6FzRS4

Is there an example of this somewhere?

[jbg]

If your package uses openssl via native-tls, you can consider enabling the vendored feature of native-tls to build openssl as part of the cargo build.

[Alexhuszagh]

This is relatively trivial now, and is well documented. An example repository of using a non-vendored, system OpenSSL install with pkg-config to find the OpenSSL installation for the aarch64 architecture is shown.

The logic is quite simple. First, create a Dockerfile with your additional dependencies:

FROM ghcr.io/cross-rs/aarch64-unknown-linux-gnu:edge
RUN dpkg --add-architecture arm64
RUN apt-get update && apt-get install --assume-yes libssl-dev:arm64

Then build the image:

docker build -t openssl:aarch64 .

Update Cross.toml to use your custom image:

[target.aarch64-unknown-linux-gnu]
image = "openssl:aarch64"

And then you can use the openssl crate. Documenting how to use abstract external dependencies is shown here.

[Alexhuszagh]

Because this is a fairly common use case, I've documented in the Recipes on the Wiki.