forked from mirrors/nixpkgs
b6363c7bc8
This is useful for EC2 AMI generation to speedup the process. In my case it removes 13min out of 45min when generating an image on EC2.
109 lines
3.1 KiB
Nix
109 lines
3.1 KiB
Nix
{ pkgs
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, lib
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, # The NixOS configuration to be installed onto the disk image.
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config
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, # The size of the disk, in megabytes.
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diskSize
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, # Whether the disk should be partitioned (with a single partition
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# containing the root filesystem) or contain the root filesystem
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# directly.
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partitioned ? true
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# Whether to invoke switch-to-configuration boot during image creation
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, installBootLoader ? true
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, # The root file system type.
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fsType ? "ext4"
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, # The initial NixOS configuration file to be copied to
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# /etc/nixos/configuration.nix.
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configFile ? null
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, # Shell code executed after the VM has finished.
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postVM ? ""
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, name ? "nixos-disk-image"
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# This prevents errors while checking nix-store validity, see
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# https://github.com/NixOS/nix/issues/1134
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, fixValidity ? true
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, format ? "raw"
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}:
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with lib;
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pkgs.vmTools.runInLinuxVM (
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pkgs.runCommand name
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{ preVM =
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''
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mkdir $out
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diskImage=$out/nixos.${if format == "qcow2" then "qcow2" else "img"}
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${pkgs.vmTools.qemu}/bin/qemu-img create -f ${format} $diskImage "${toString diskSize}M"
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mv closure xchg/
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'';
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buildInputs = [ pkgs.utillinux pkgs.perl pkgs.e2fsprogs pkgs.parted ];
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exportReferencesGraph =
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[ "closure" config.system.build.toplevel ];
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inherit postVM;
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memSize = 1024;
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}
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''
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${if partitioned then ''
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# Create a single / partition.
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parted /dev/vda mklabel msdos
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parted /dev/vda -- mkpart primary ext2 1M -1s
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. /sys/class/block/vda1/uevent
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mknod /dev/vda1 b $MAJOR $MINOR
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rootDisk=/dev/vda1
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'' else ''
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rootDisk=/dev/vda
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''}
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# Create an empty filesystem and mount it.
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mkfs.${fsType} -L nixos $rootDisk
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mkdir /mnt
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mount $rootDisk /mnt
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# Register the paths in the Nix database.
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printRegistration=1 perl ${pkgs.pathsFromGraph} /tmp/xchg/closure | \
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${config.nix.package.out}/bin/nix-store --load-db --option build-users-group ""
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${if fixValidity then ''
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# Add missing size/hash fields to the database. FIXME:
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# exportReferencesGraph should provide these directly.
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${config.nix.package.out}/bin/nix-store --verify --check-contents --option build-users-group ""
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'' else ""}
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# In case the bootloader tries to write to /dev/sda…
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ln -s vda /dev/xvda
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ln -s vda /dev/sda
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# Install the closure onto the image
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USER=root ${config.system.build.nixos-install}/bin/nixos-install \
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--closure ${config.system.build.toplevel} \
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--no-channel-copy \
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--no-root-passwd \
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${optionalString (!installBootLoader) "--no-bootloader"}
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# Install a configuration.nix.
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mkdir -p /mnt/etc/nixos
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${optionalString (configFile != null) ''
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cp ${configFile} /mnt/etc/nixos/configuration.nix
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''}
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# Remove /etc/machine-id so that each machine cloning this image will get its own id
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rm -f /mnt/etc/machine-id
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umount /mnt
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# Make sure resize2fs works
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${optionalString (fsType == "ext4") ''
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tune2fs -c 0 -i 0 $rootDisk
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''}
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''
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)
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