Add an out of tree kernel module to a custom AMI

[snirzango]

Hey all, im trying to add&load an out of tree kernel module to bottlerocket AMI, i managed to compile an incp.ko file using kmod kit for aws-k8s-1.31-v1.30.0.
i than created a incp-module dir under packages with the incp.ko file and:
Cargo.toml:
[package] name = "incp-module" version = "0.1.0" edition = "2018" license = "Apache-2.0" publish = false description = "A Bottlerocket package for the incp.ko kernel module"
and a build.rs file:
`use std::env;
use std::fs;
use std::path::PathBuf;

fn main() {
// The Bottlerocket build system sets various env vars.
// One common approach is to parse the kernel version or
// the output directory from environment variables.
//
// For example, if you have a custom environment variable for
// the kernel version or if you want to provide it, you’d do:
//
// let kernel_version = env::var("BUILDSYS_KERNEL_VERSION")
// .unwrap_or_else(|_| "unknown-kernel-version".to_string());
//
// But for this minimal example, we'll assume "5.10.123" or something
// is known, or you can pass it in at build time. Adjust accordingly.

// In Bottlerocket builds, "OUT_DIR" is where we can place final artifacts.
let out_dir = env::var("OUT_DIR").expect("OUT_DIR is not set by the build system");

// Let's assume the kernel version is provided by the build environment
// or you can hardcode it. We'll do a fallback if not set.
let kernel_version = env::var("KERNEL_VERSION")
    .unwrap_or_else(|_| "6.1.119".to_string());

// Construct the path where we want to install the module in the
// final root filesystem image. Bottlerocket expects the final
// filesystem layout to appear under `OUT_DIR`/root/.
//
// E.g.: <OUT_DIR>/root/usr/lib/modules/<kernel_version>/extra/
let mut install_path = PathBuf::from(&out_dir);
install_path.push("root");
install_path.push("lib");
install_path.push("modules");
install_path.push(&kernel_version);
install_path.push("kernel");

// Create the directory if it doesn't exist.
fs::create_dir_all(&install_path)
    .expect("Failed to create module destination directory");

// Adjust the path to your actual incp.ko location.
let source_path = PathBuf::from("incp.ko");
let destination_path = install_path.join("incp.ko");

fs::copy(&source_path, &destination_path)
    .unwrap_or_else(|_| panic!("Failed to copy {:?} to {:?}", source_path, destination_path));

println!(
    "cargo:warning=Copied incp.ko to {:?}",
    destination_path.display()
);

// If you need to sign the module or run depmod, do it here.
// Example:
// std::process::Command::new("scripts/sign-module.sh")
//     .arg(destination_path.to_string_lossy().to_string())
//     .status()
//     .expect("Failed to sign kernel module");

}i added the the packa[package]
name = "aws-k8s-1_31"
version = "0.1.0"
edition = "2021"
publish = false
build = "../build.rs"
exclude = ["README.md"]

[package.metadata.build-variant.image-features]
grub-set-private-var = true
uefi-secure-boot = true
xfs-data-partition = true
systemd-networkd = true

[package.metadata.build-variant]
included-packages = [
# core
"release",
"kernel-6.1",
# k8s
"cni",
"cni-plugins",
"kubelet-1.31",
"aws-iam-authenticator",
"incp-module",
]

kernel-parameters = [
"console=tty0",
"console=ttyS0,115200n8",
"net.ifnames=0",
"netdog.default-interface=eth0:dhcp4,dhcp6?",
"quiet",
]

[lib]
path = "../variants.rs"

[build-dependencies]
settings-defaults = { path = "../../packages/settings-defaults" }
settings-plugins = { path = "../../packages/settings-plugins" }
settings-migrations = { path = "../../packages/settings-migrations" }
incp-module = { path = "../../packages/incp-module" }`

and added members = [ "packages/*", to the Cargo.toml on the bottlerocket dir
when running cargo make --verbose -e BUILDSYS_VARIANT=aws-k8s-1.30 -e BUILDSYS_ARCH=aarch64 -e PACKAGE=incp-module build-package
the process looks like it succeeding but there is nothing on the build/rpms part and the cargo make build variant failed.

any idea what am i doing wrong?

[arnaldo2792]

Hey @snirzango! Thanks for your interest on building your own AMI. Could you please share the output of your command:

cargo make --verbose -e BUILDSYS_VARIANT=aws-k8s-1.30 -e BUILDSYS_ARCH=aarch64 -e PACKAGE=incp-module build-package

Along with that, could you please make sure you run cargo check on your variants directory? You need to make sure that the Cargo.lock files are regenerated after you added your package.

And just a final ask, could you please fix the formatting of your description so that it is easier to read?