# Configuration for Amazon EC2 instances. (Note that this file is a # misnomer - it should be "amazon-config.nix" or so, not # "amazon-image.nix", since it's used not only to build images but # also to reconfigure instances. However, we can't rename it because # existing "configuration.nix" files on EC2 instances refer to it.) { config, lib, pkgs, ... }: with lib; let cfg = config.ec2; in { imports = [ ../profiles/headless.nix # Note: While we do use the headless profile, we also explicitly # turn on the serial console on ttyS0 below. This is because # AWS does support accessing the serial console: # https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configure-access-to-serial-console.html ./ec2-data.nix ./amazon-init.nix ]; config = { assertions = [ ]; boot.growPartition = true; fileSystems."/" = mkIf (!cfg.zfs.enable) { device = "/dev/disk/by-label/nixos"; fsType = "ext4"; autoResize = true; }; fileSystems."/boot" = mkIf (cfg.efi || cfg.zfs.enable) { # The ZFS image uses a partition labeled ESP whether or not we're # booting with EFI. device = "/dev/disk/by-label/ESP"; fsType = "vfat"; }; services.zfs.expandOnBoot = mkIf cfg.zfs.enable "all"; boot.zfs.devNodes = mkIf cfg.zfs.enable "/dev/"; boot.extraModulePackages = [ config.boot.kernelPackages.ena ]; boot.initrd.kernelModules = [ "xen-blkfront" ]; boot.initrd.availableKernelModules = [ "nvme" ]; boot.kernelParams = [ "console=ttyS0,115200n8" "random.trust_cpu=on" ]; # Prevent the nouveau kernel module from being loaded, as it # interferes with the nvidia/nvidia-uvm modules needed for CUDA. # Also blacklist xen_fbfront to prevent a 30 second delay during # boot. boot.blacklistedKernelModules = [ "nouveau" "xen_fbfront" ]; boot.loader.grub.device = if cfg.efi then "nodev" else "/dev/xvda"; boot.loader.grub.efiSupport = cfg.efi; boot.loader.grub.efiInstallAsRemovable = cfg.efi; boot.loader.timeout = 1; boot.loader.grub.extraConfig = '' serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1 terminal_output console serial terminal_input console serial ''; systemd.services.fetch-ec2-metadata = { wantedBy = [ "multi-user.target" ]; after = ["network-online.target"]; path = [ pkgs.curl ]; script = builtins.readFile ./ec2-metadata-fetcher.sh; serviceConfig.Type = "oneshot"; serviceConfig.StandardOutput = "journal+console"; }; # Allow root logins only using the SSH key that the user specified # at instance creation time. services.openssh.enable = true; services.openssh.settings.PermitRootLogin = "prohibit-password"; # Enable the serial console on ttyS0 systemd.services."serial-getty@ttyS0".enable = true; # Creates symlinks for block device names. services.udev.packages = [ pkgs.amazon-ec2-utils ]; # Force getting the hostname from EC2. networking.hostName = mkDefault ""; # Always include cryptsetup so that Charon can use it. environment.systemPackages = [ pkgs.cryptsetup ]; # EC2 has its own NTP server provided by the hypervisor networking.timeServers = [ "169.254.169.123" ]; # udisks has become too bloated to have in a headless system # (e.g. it depends on GTK). services.udisks2.enable = false; }; }