Add Rust toolchains and example rust library to Collector

[Stringy]

Description

Adds a Rust toolchain into Collector, allowing us to write Rust crates and call into them from C++. The idea is that we can gradually increase the amount of Rust in the project and take advantage of its helpful features including memory / thread safety.

[Stringy]

This is a slightly modified version of the cmake module taken from here: https://github.com/micahsnyder/cmake-rust-demo/blob/main/cmake/FindRust.cmake

The main addition is an include directory to pass to the build commands so we can centralise cbindgen headers

[Molter73]

You can probably remove one level of indentation with a let-else here

Suggested change

	if let Ok(file) = File::open(path.into()) {
	let Ok(file) = File::open(path.into()) else { return Default::default(); };

[Molter73]

Suggested change

	let root = PathBuf::from(std::env::var("COLLECTOR_HOST_PATH").unwrap_or("/host".to_string()));
	root.join(path.into())
	let root = std::env::var("COLLECTOR_HOST_PATH").unwrap_or("/host".to_string());
	PathBuf::from(root).join(path.into())

[Molter73]

Do we need to host_path this as well?

Suggested change

	if let Ok(file) = File::open("/etc/os-release") {
	if let Ok(file) = File::open(host_path("/etc/os-release")) {

[Molter73]

Now I'm wondering, do we need to add the = to these?

Suggested change

	Ok(s) if s.starts_with("ID") => os = s["ID ".len()..].to_owned(),
	Ok(s) if s.starts_with("ID=") => os = s["ID=".len()..].to_owned(),

[Molter73]

Do we need a vector? I would assume you can just use an array here

Suggested change

	let hostname_paths = vec![
	host_path("/etc/hostname"),
	host_path("/proc/sys/kernel/hostname"),
	];
	for path in hostname_paths {
	for path in [
	host_path("/etc/hostname"),
	host_path("/proc/sys/kernel/hostname"),
	] {

[Molter73]

Could we use standard == in these checks?

Suggested change

	self.os_id().eq("coreos")
	self.os_id() == "coreos"

[Molter73]

Suggested change

	let locations = vec![
	// try canonical vmlinux BTF through sysfs first
	("/sys/kernel/btf/vmlinux".to_string(), false),
	// fall back to trying to find vmlinux on disk otherwise
	(format!("/boot/vmlinux-{}", self.kernel.release), false),
	(
	format!(
	"/lib/modules/{}/vmlinux-{}",
	self.kernel.release, self.kernel.release
	),
	false,
	),
	(
	format!("/lib/modules/{}/build/vmlinux", self.kernel.release),
	false,
	),
	(
	format!("/usr/lib/modules/{}/kernel/vmlinux", self.kernel.release),
	true,
	),
	(
	format!("/usr/lib/debug/boot/vmlinux-{}", self.kernel.release),
	true,
	),
	(
	format!("/usr/lib/debug/boot/vmlinux-{}.debug", self.kernel.release),
	true,
	),
	(
	format!("/usr/lib/debug/lib/modules/{}/vmlinux", self.kernel.release),
	true,
	),
	];
	let release = &self.kernel.release;
	let locations = vec![
	// try canonical vmlinux BTF through sysfs first
	("/sys/kernel/btf/vmlinux".to_string(), false),
	// fall back to trying to find vmlinux on disk otherwise
	(format!("/boot/vmlinux-{release}"), false),
	(format!("/lib/modules/{release}/vmlinux-{release}"), false),
	(format!("/lib/modules/{release}/build/vmlinux"), false),
	(format!("/usr/lib/modules/{release}/kernel/vmlinux"), true),
	(format!("/usr/lib/debug/boot/vmlinux-{release}"), true,),
	(format!("/usr/lib/debug/boot/vmlinux-{release}.debug"), true),
	(format!("/usr/lib/debug/lib/modules/{release}/vmlinux"), true),
	];

[Molter73]

You could also directly call host_path on the ones that need to be mapped and drop from a vector of tuples to a vector of paths.

[Molter73]

Suggested change

	for location in locations {
	let path = if location.1 {
	host_path(location.0)
	} else {
	PathBuf::from(location.0)
	};
	if path.exists() {
	return true;
	}
	}
	for (path, on_host) in locations {
	let path = if on_host {
	host_path(path)
	} else {
	PathBuf::from(path)
	};
	if path.exists() {
	return true;
	}
	}

[Molter73]

Do we need these to be &str? Can't we use straight up String? Most places it looks like we already have those, it would save creating/copying strings.