Rust Linux version glibc not found - compile for different glibc / libc6 version - linux

Question

I compile a Rust binary on one Linux system and try to run it on another. When I run the program I get:
./hello-rust: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.32' not found (required by ./hello-rust)
GLIBC aka libc6 is installed on the system, however, the version is 2.31 Is there a way to compile the program for a less recent version of libc6?

Answer 1

Per the issue: https://github.com/rust-lang/rust/issues/57497 - there's no way to tell the Rust compiler to link a different library other than the one installed on the system.
This means I have to compile the binary on a system that has a less recent version of libc6 installed - then the binary should be compatible with the same version of libc6, or a more recent version*
The most convenient way of doing that would by using a Docker image that has the target libc6 version and rustup.
For myself, the official Rust docker image had the correct version I could use to compile for my target.
In the working directory:
sudo docker pull rust
sudo docker run --rm --user "$(id -u)":"$(id -g)" -v "$PWD":/usr/src/myapp -w /usr/src/myapp rust cargo build --release
If the official image, which is based on Debian does not satisfy the version requirement, you will have to create a custom docker image, i.e.:
fork the official Rust docker image and set it to use an older version of Debian
or create an image that is based on an older Debian or other Linux distro image and configure it to install rustup
* I could use a binary compiled with libc6 2.31 on a system that has libc6 2.32 - I'm not sure how far backwards compatibility goes.

Answer 2

If you want a simple way of doing it, try the cross project. It requires Docker, but is super easy.
cargo install cross --git https://github.com/cross-rs/cross
Make sure your user can run Docker:
sudo usermod -aG docker ${USER}
Then, for example, if you want to compile for armv6l arch:
cross build --target arm-unknown-linux-gnueabihf --release
If you want to compile for armv7l:
cross build --target armv7-unknown-linux-gnueabihf --release
The compiled file will be placed in the usual target/armv7-unknown-linux-gnueabihf/release/... folder.
Make sure to check the proper destination arch in the targeted system with the command arch. Example:
pi#raspberrypi:~ $ arch
armv6l