111 lines
3.7 KiB
Nix
111 lines
3.7 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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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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wants = [ "network-online.target" ];
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after = ["network-online.target"];
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path = [ pkgs.curl ];
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script = builtins.readFile ./ec2-metadata-fetcher.sh;
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serviceConfig.Type = "oneshot";
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serviceConfig.StandardOutput = "journal+console";
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};
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# Amazon-issued AMIs include the SSM Agent by default, so we do the same.
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# https://docs.aws.amazon.com/systems-manager/latest/userguide/ami-preinstalled-agent.html
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services.amazon-ssm-agent.enable = true;
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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.settings.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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meta.maintainers = with maintainers; [ arianvp ];
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}
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