This also removes automatic enablement/mounting of instance store swap
devices and ext3 filesystems. This behaviour is strongly opinionated
and shouldn't be enabled by default.
The unionfs behaviour never took effect anyway, because the AMI
manifest path only exists for instance store-backed AMIs, which have
not been supported by nixpkgs since
84742e2293 (2019).
111 lines
3.5 KiB
Nix
111 lines
3.5 KiB
Nix
# Configuration for Amazon EC2 instances. (Note that this file is a
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# misnomer - it should be "amazon-config.nix" or so, not
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# "amazon-image.nix", since it's used not only to build images but
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# also to reconfigure instances. However, we can't rename it because
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# existing "configuration.nix" files on EC2 instances refer to it.)
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{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.ec2;
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in
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{
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imports = [
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../profiles/headless.nix
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# Note: While we do use the headless profile, we also explicitly
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# turn on the serial console on ttyS0 below. This is because
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# AWS does support accessing the serial console:
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# https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configure-access-to-serial-console.html
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./ec2-data.nix
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./amazon-init.nix
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];
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config = {
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assertions = [
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{ assertion = versionOlder config.boot.kernelPackages.kernel.version "5.17";
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message = "ENA driver fails to build with kernel >= 5.17";
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}
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];
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boot.growPartition = true;
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fileSystems."/" = mkIf (!cfg.zfs.enable) {
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device = "/dev/disk/by-label/nixos";
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fsType = "ext4";
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autoResize = true;
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};
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fileSystems."/boot" = mkIf (cfg.efi || cfg.zfs.enable) {
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# The ZFS image uses a partition labeled ESP whether or not we're
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# booting with EFI.
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device = "/dev/disk/by-label/ESP";
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fsType = "vfat";
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};
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services.zfs.expandOnBoot = mkIf cfg.zfs.enable "all";
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boot.zfs.devNodes = mkIf cfg.zfs.enable "/dev/";
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boot.extraModulePackages = [
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config.boot.kernelPackages.ena
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];
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boot.initrd.kernelModules = [ "xen-blkfront" ];
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boot.initrd.availableKernelModules = [ "nvme" ];
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boot.kernelParams = [ "console=ttyS0,115200n8" "random.trust_cpu=on" ];
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# Prevent the nouveau kernel module from being loaded, as it
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# interferes with the nvidia/nvidia-uvm modules needed for CUDA.
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# Also blacklist xen_fbfront to prevent a 30 second delay during
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# boot.
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boot.blacklistedKernelModules = [ "nouveau" "xen_fbfront" ];
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boot.loader.grub.device = if cfg.efi then "nodev" else "/dev/xvda";
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boot.loader.grub.efiSupport = cfg.efi;
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boot.loader.grub.efiInstallAsRemovable = cfg.efi;
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boot.loader.timeout = 1;
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boot.loader.grub.extraConfig = ''
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serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
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terminal_output console serial
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terminal_input console serial
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'';
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systemd.services.fetch-ec2-metadata = {
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wantedBy = [ "multi-user.target" ];
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path = [ pkgs.wget ];
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script = pkgs.callPackage ./ec2-metadata-fetcher.nix {
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targetRoot = "/";
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wgetExtraOptions = "";
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};
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serviceConfig.Type = "oneshot";
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};
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# Allow root logins only using the SSH key that the user specified
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# at instance creation time.
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services.openssh.enable = true;
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services.openssh.permitRootLogin = "prohibit-password";
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# Enable the serial console on ttyS0
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systemd.services."serial-getty@ttyS0".enable = true;
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# Creates symlinks for block device names.
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services.udev.packages = [ pkgs.amazon-ec2-utils ];
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# Force getting the hostname from EC2.
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networking.hostName = mkDefault "";
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# Always include cryptsetup so that Charon can use it.
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environment.systemPackages = [ pkgs.cryptsetup ];
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# EC2 has its own NTP server provided by the hypervisor
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networking.timeServers = [ "169.254.169.123" ];
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# udisks has become too bloated to have in a headless system
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# (e.g. it depends on GTK).
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services.udisks2.enable = false;
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};
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}
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