# 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 ./ec2-data.nix ./amazon-init.nix ]; config = { assertions = [ { assertion = cfg.hvm; message = "Paravirtualized EC2 instances are no longer supported."; } ]; boot.growPartition = cfg.hvm; fileSystems."/" = { device = "/dev/disk/by-label/nixos"; autoResize = true; }; boot.extraModulePackages = [ config.boot.kernelPackages.ixgbevf config.boot.kernelPackages.ena ]; boot.initrd.kernelModules = [ "xen-blkfront" "xen-netfront" ]; boot.initrd.availableKernelModules = [ "ixgbevf" "ena" "nvme" ]; boot.kernelParams = mkIf cfg.hvm [ "console=ttyS0" ]; # 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" ]; # Generate a GRUB menu. Amazon's pv-grub uses this to boot our kernel/initrd. boot.loader.grub.version = if cfg.hvm then 2 else 1; boot.loader.grub.device = if cfg.hvm then "/dev/xvda" else "nodev"; boot.loader.grub.extraPerEntryConfig = mkIf (!cfg.hvm) "root (hd0)"; boot.loader.timeout = 0; boot.initrd.postDeviceCommands = '' # Force udev to exit to prevent random "Device or resource busy # while trying to open /dev/xvda" errors from fsck. udevadm control --exit || true ''; boot.initrd.network.enable = true; # Mount all formatted ephemeral disks and activate all swap devices. # We cannot do this with the ‘fileSystems’ and ‘swapDevices’ options # because the set of devices is dependent on the instance type # (e.g. "m1.large" has one ephemeral filesystem and one swap device, # while "m1.large" has two ephemeral filesystems and no swap # devices). Also, put /tmp and /var on /disk0, since it has a lot # more space than the root device. Similarly, "move" /nix to /disk0 # by layering a unionfs-fuse mount on top of it so we have a lot more space for # Nix operations. boot.initrd.postMountCommands = '' metaDir=$targetRoot/etc/ec2-metadata mkdir -m 0755 -p "$metaDir" echo "getting EC2 instance metadata..." if ! [ -e "$metaDir/ami-manifest-path" ]; then wget -q -O "$metaDir/ami-manifest-path" http://169.254.169.254/1.0/meta-data/ami-manifest-path fi if ! [ -e "$metaDir/user-data" ]; then wget -q -O "$metaDir/user-data" http://169.254.169.254/1.0/user-data && chmod 600 "$metaDir/user-data" fi if ! [ -e "$metaDir/hostname" ]; then wget -q -O "$metaDir/hostname" http://169.254.169.254/1.0/meta-data/hostname fi if ! [ -e "$metaDir/public-keys-0-openssh-key" ]; then wget -q -O "$metaDir/public-keys-0-openssh-key" http://169.254.169.254/1.0/meta-data/public-keys/0/openssh-key fi diskNr=0 diskForUnionfs= for device in /dev/xvd[abcde]*; do if [ "$device" = /dev/xvda -o "$device" = /dev/xvda1 ]; then continue; fi fsType=$(blkid -o value -s TYPE "$device" || true) if [ "$fsType" = swap ]; then echo "activating swap device $device..." swapon "$device" || true elif [ "$fsType" = ext3 ]; then mp="/disk$diskNr" diskNr=$((diskNr + 1)) if mountFS "$device" "$mp" "" ext3; then if [ -z "$diskForUnionfs" ]; then diskForUnionfs="$mp"; fi fi else echo "skipping unknown device type $device" fi done if [ -n "$diskForUnionfs" ]; then mkdir -m 755 -p $targetRoot/$diskForUnionfs/root mkdir -m 1777 -p $targetRoot/$diskForUnionfs/root/tmp $targetRoot/tmp mount --bind $targetRoot/$diskForUnionfs/root/tmp $targetRoot/tmp if [ "$(cat "$metaDir/ami-manifest-path")" != "(unknown)" ]; then mkdir -m 755 -p $targetRoot/$diskForUnionfs/root/var $targetRoot/var mount --bind $targetRoot/$diskForUnionfs/root/var $targetRoot/var mkdir -p /unionfs-chroot/ro-nix mount --rbind $targetRoot/nix /unionfs-chroot/ro-nix mkdir -m 755 -p $targetRoot/$diskForUnionfs/root/nix mkdir -p /unionfs-chroot/rw-nix mount --rbind $targetRoot/$diskForUnionfs/root/nix /unionfs-chroot/rw-nix unionfs -o allow_other,cow,nonempty,chroot=/unionfs-chroot,max_files=32768 /rw-nix=RW:/ro-nix=RO $targetRoot/nix fi fi ''; boot.initrd.extraUtilsCommands = '' # We need swapon in the initrd. copy_bin_and_libs ${pkgs.utillinux}/sbin/swapon ''; # Don't put old configurations in the GRUB menu. The user has no # way to select them anyway. boot.loader.grub.configurationLimit = 0; # Allow root logins only using the SSH key that the user specified # at instance creation time. services.openssh.enable = true; services.openssh.permitRootLogin = "prohibit-password"; # Force getting the hostname from EC2. networking.hostName = mkDefault ""; # Always include cryptsetup so that Charon can use it. environment.systemPackages = [ pkgs.cryptsetup ]; boot.initrd.supportedFilesystems = [ "unionfs-fuse" ]; # EC2 has its own NTP server provided by the hypervisor networking.timeServers = [ "169.254.169.123" ]; }; }