nixos-installer/lib/setup-scripts/maintenance.sh

##
# NixOS Maintenance
##

declare-command register-vbox diskImages bridgeTo? << 'EOD'
On the host and for the user it is called by, creates/registers a VirtualBox VM meant to run the shells target host. Requires the path to the target host's »diskImage« as the result of running the install script. The image file may not be deleted or moved. If »bridgeTo« is set (to a host interface name, e.g. as »eth0«), it is added as bridged network "Adapter 2" (which some hosts need).
EOD
function register-vbox {(
    diskImages=$1 ; bridgeTo=${2:-}
    vmName="nixos-@{config.networking.hostName}"
    VBoxManage=$( PATH=$hostPath which VBoxManage ) || exit # The host is supposed to run these anyway, and »pkgs.virtualbox« is marked broken on »aarch64«.

    $VBoxManage createvm --name "$vmName" --register --ostype Linux26_64 || exit
    $VBoxManage modifyvm "$vmName" --memory 2048 --pae off --firmware efi || exit

    $VBoxManage storagectl "$vmName" --name SATA --add sata --portcount 4 --bootable on --hostiocache on || exit

    index=0 ; for decl in ${diskImages//:/ } ; do
        diskImage=${decl/*=/}
        if [[ ! -e $diskImage.vmdk ]] ; then
            $VBoxManage internalcommands createrawvmdk -filename $diskImage.vmdk -rawdisk $diskImage || exit # pass-through
            #VBoxManage convertfromraw --format VDI $diskImage $diskImage.vmdk && rm $diskImage # convert
        fi
        $VBoxManage storageattach "$vmName" --storagectl SATA --port $(( index++ )) --device 0 --type hdd --medium $diskImage.vmdk || exit
    done

    if [[ $bridgeTo ]] ; then # VBoxManage list bridgedifs
        $VBoxManage modifyvm "$vmName" --nic2 bridged --bridgeadapter2 $bridgeTo || exit
    fi

    # The serial settings between qemu and vBox seem incompatible. With a simple »console=ttyS0«, vBox hangs on start. So just disable this for now an use qemu for headless setups. The UX here is awful anyway.
   #$VBoxManage modifyvm "$vmName" --uart1 0x3F8 4 --uartmode1 server /run/user/$(id -u)/$vmName.socket # (guest sets speed)

    set +x # avoid double-echoing
    echo '# VM info:'
    echo " VBoxManage showvminfo $vmName"
    echo '# start VM:'
    echo " VBoxManage startvm $vmName --type headless"
    echo '# kill VM:'
    echo " VBoxManage controlvm $vmName poweroff"
   #echo '# create TTY:'
   #echo " socat UNIX-CONNECT:/run/user/$(id -u)/$vmName.socket PTY,link=/run/user/$(id -u)/$vmName.pty"
   #echo '# connect TTY:'
   #echo " screen /run/user/$(id -u)/$vmName.pty"
    echo '# screenshot:'
    echo " ssh $(@{native.inetutils}/bin/hostname) VBoxManage controlvm $vmName screenshotpng /dev/stdout | display"
)}

declare-command run-qemu diskImages qemuArgs... << 'EOD'
Runs a host in a QEMU VM, directly from its bootable disks, without requiring any change in it's configuration.
This function infers many qemu options from the target system's configuration and the current host system.
»diskImages« may be passed in the same format as to the installer. Any image files passed are ensured to be loop-mounted. »root« may also pass device paths.
EOD
declare-flag run-qemu dry-run           "" "Instead of running the (main) qemu (and install) command, only print it."
declare-flag run-qemu efi               "" "Treat the target system as EFI system, even if not recognized as such automatically."
declare-flag run-qemu efi-vars      "path" "For »--efi« systems, path to a file storing the EFI variables. The default is in »XDG_RUNTIME_DIR«, i.e. it does not persist across host reboots."
declare-flag run-qemu graphic           "" "Open a graphical window even of the target system logs to serial and not (explicitly) TTY1."
declare-flag run-qemu install "[1|always]" "If any of the guest system's disk images does not exist, perform the its installation before starting the VM. If set to »always«, always install before starting the VM. With this flag set, »diskImages« defaults to paths in »/tmp/."
declare-flag run-qemu mem            "num" "VM RAM in MiB (»qemu -m«)."
declare-flag run-qemu no-kvm            "" "Do not rey to use (or complain about the unavailability of) KVM."
declare-flag run-qemu nat-fw    "forwards" "Port forwards to the guest's NATed NIC. E.g: »--nat-fw=:8000-:8000,:8001-:8001,127.0.0.1:2022-:22«."
declare-flag run-qemu no-nat            "" "Do not provide a NATed NIC to the guest."
declare-flag run-qemu nic "type[,options]" "Create an additional network interface using the »-nic« flag. Automatically sets a decent »model« and a »mac« derived from »config.networking.hostId«.
Example 1 (connect two VMs, unprivileged):
$ ... --nic=socket,listen=:4321 # once
$ ... --nic=socket,connect=:4321 # once
Example 2 (connect many VMs, unprivileged):
$ nix shell nixpkgs#vde2 --command vde_switch -sock /tmp/vm-net
$ ... --nic=vde,sock=/tmp/vm-net # multiple times
"
declare-flag run-qemu no-serial         "" "Do not connect the calling terminal to a serial adapter the guest can log to and open a terminal on the guests serial, as would be the default if the guests logs to ttyS0."
declare-flag run-qemu share        "decls" "Host dirs to make available as network shares for the guest, as space separated list of »name:host-path,options. E.g. »--share='foo:/home/user/foo,readonly=on bar:/tmp/bar«. In the VM hte share can be mounted with: »$ mount -t 9p -o trans=virtio -o version=9p2000.L -o msize=4194304 -o ro foo /foo«."
declare-flag run-qemu smp            "num" "Number of guest CPU cores."
declare-flag run-qemu usb-port      "path" "A physical USB port (or hub) to pass to the guest (e.g. a YubiKey for unlocking). Specified as »<bus>-<port>«, where bus and port refer to the physical USB port »/sys/bus/usb/devices/<bus>-<port>« (see »lsusb -tvv«). E.g.: »--usb-port=3-1.1.1.4«."
declare-flag run-qemu virtio-blk        "" "Pass the system's disks/images as virtio disks, instead of using AHCI+IDE. Default iff »boot.initrd.availableKernelModules« includes »virtio_blk« (because it requires that driver)."
function run-qemu {
    if [[ ${args[install]:-} && ! ${argv[0]:-} ]] ; then argv[0]=/tmp/nixos-vm/@{config.installer.outputName:-@{config.system.name}}/ ; fi
    diskImages=${argv[0]:?} ; argv=( "${argv[@]:1}" )

    local qemu=( )

    if [[ @{pkgs.system} == "@{native.system}" ]] ; then
        qemu=( $( build-lazy @{native.qemu_kvm.drvPath!unsafeDiscardStringContext} )/bin/qemu-kvm ) || return
        if [[ ! ${args[no-kvm]:-} && -r /dev/kvm && -w /dev/kvm ]] ; then
            # For KVM to work, vBox must not be running anything at the same time (and vBox hangs on start if qemu runs). Pass »--no-kvm« and accept ~10x slowdown, or stop vBox.
            qemu+=( -enable-kvm -cpu host )
            if [[ ! ${args[smp]:-} ]] ; then qemu+=( -smp 4 ) ; fi # else the emulation is single-threaded anyway
        else
            if [[ ! ${args[no-kvm]:-} && ! ${args[quiet]:-} ]] ; then
                echo "KVM is not available (for the current user). Running without hardware acceleration." 1>&2
            fi
            qemu+=( -machine accel=tcg ) # this may suppress warnings that qemu is using tcg (slow) instead of kvm
        fi
    else
        qemu=( $( build-lazy @{native.qemu_full.drvPath!unsafeDiscardStringContext} )/bin/qemu-system-@{pkgs.system%%-linux} ) || return
    fi
    if [[ @{pkgs.system} == aarch64-* ]] ; then
        qemu+=( -machine type=virt ) # aarch64 has no default, but this seems good
    fi ; qemu+=( -cpu max )

    qemu+=( -m ${args[mem]:-2048} )
    if [[ ${args[smp]:-} ]] ; then qemu+=( -smp ${args[smp]} ) ; fi

    if [[ @{config.virtualisation.useEFIBoot:-} || @{config.boot.loader.systemd-boot.enable} || ${args[efi]:-} ]] ; then # UEFI. Otherwise it boots SeaBIOS.
        local ovmf ; ovmf=$( build-lazy @{pkgs.OVMF.drvPath!unsafeDiscardStringContext} fd ) || return
        #qemu+=( -bios ${ovmf}/FV/OVMF.fd ) # This works, but is a legacy fallback that stores the EFI vars in /NvVars on the EFI partition (which is really bad).
        local fwName=OVMF ; if [[ @{pkgs.system} == aarch64-* ]] ; then fwName=AAVMF ; fi # fwName=QEMU
        qemu+=( -drive file=${ovmf}/FV/${fwName}_CODE.fd,if=pflash,format=raw,unit=0,readonly=on )
        local efiVars=${args[efi-vars]:-"${XDG_RUNTIME_DIR:-/run/user/$(id -u)}/qemu-@{config.installer.outputName:-@{config.system.name}}-VARS.fd"}
        qemu+=( -drive file="$efiVars",if=pflash,format=raw,unit=1 )
        if [[ ! -e "$efiVars" ]] ; then mkdir -pm700 "$( dirname "$efiVars" )" ; cat ${ovmf}/FV/${fwName}_VARS.fd >"$efiVars" || return ; fi
        # https://lists.gnu.org/archive/html/qemu-discuss/2018-04/msg00045.html
    fi
#   if [[ @{pkgs.system} == aarch64-* ]] ; then
#       qemu+=( -kernel @{config.system.build.kernel}/Image -initrd @{config.system.build.initialRamdisk}/initrd -append "$(echo -n "@{config.boot.kernelParams[@]}")" )
#   fi

    if [[ $diskImages == */ ]] ; then
        disks=( ${diskImages}primary.img ) ; for name in "@{!config.setup.disks.devices[@]}" ; do if [[ $name != primary ]] ; then disks+=( ${diskImages}${name}.img ) ; fi ; done
    else disks=( ${diskImages//:/ } ) ; fi

    [[ ' '"@{boot.initrd.availableKernelModules[@]}"' ' != *' 'virtio_blk' '* ]] || args[virtio-blk]=1
    local index ; for index in ${!disks[@]} ; do
#       qemu+=( -drive format=raw,if=ide,file="${disks[$index]/*=/}" ) # »if=ide« is the default, which these days isn't great for driver support inside the VM
        qemu+=( -drive format=raw,file="${disks[$index]/*=/}",media=disk,if=none,index=${index},id=drive${index} ) # create the disk drive, without attaching it, name it driveX

        if [[ ! ${args[virtio-blk]:-} ]] ; then
            qemu+=( -device ahci,acpi-index=${index},id=ahci${index} ) # create an (ich9-)AHCI bus named »ahciX«
            qemu+=( -device ide-hd,drive=drive${index},bus=ahci${index}.${index} ) # attach IDE?! disk driveX as device X on bus »ahciX«
        else
            qemu+=( -device virtio-blk-pci,drive=drive${index},disable-modern=on,disable-legacy=off ) # this should be faster, but seems to require guest drivers
        fi
    done

    if [[ ${args[share]:-} ]] ; then # e.g. --share='foo:/home/user/foo,readonly=on bar:/tmp/bar'
        local share ; for share in ${args[share]} ; do
            qemu+=( -virtfs local,security_model=none,mount_tag=${share/:/,path=} )
            # In the VM: $ mount -t 9p -o trans=virtio -o version=9p2000.L -o msize=4194304 -o ro foo /foo
        done
    fi

    # Add »config.boot.kernelParams = [ "console=tty1" "console=ttyS0" ]« to log to serial (»ttyS0«) and/or the display (»tty1«), preferring the last »console« option for the initrd shell (if enabled and requested).
    local logSerial= ; if [[ ' '"@{config.boot.kernelParams[@]}"' ' == *' console=ttyS0'@( |,)* ]] ; then logSerial=1 ; fi
    local logScreen= ; if [[ ' '"@{config.boot.kernelParams[@]}"' ' == *' console=tty1 '* ]] ; then logScreen=1 ; fi
    if [[ ! ${args[no-serial]:-} && $logSerial ]] ; then
        if [[ $logScreen || ${args[graphic]:-} ]] ; then
            qemu+=( -serial mon:stdio )
        else
            qemu+=( -nographic ) # Without »console=tty1« or no »console=...« parameter, boot messages won't be on the screen.
        fi
    fi

    if [[ ! ${args[no-nat]:-} ]] ; then # e.g. --nat-fw=:8000-:8000,:8001-:8001,127.0.0.1:2022-:22
        qemu+=( -nic user,model=virtio-net-pci${args[nat-fw]:+,hostfwd=tcp:${args[nat-fw]//,/,hostfwd=tcp:}} ) # NATed, IPs: 10.0.2.15+/24, gateway/host: 10.0.2.2, DNS: 10.0.2.3
    fi
    if [[ ${args[nic]:-} ]] ; then
        [[ @{config.networking.hostId} =~ ^(.)(.)(.)(.)(.)(.)(.)(.)$ ]] && mac=$( printf "52:54:%s%s:%s%s:%s%s:%s%s" "${BASH_REMATCH[@]:1}" ) || { echo 'Invalid hostId' &>2 ; return; }
        qemu+=( -nic model=virtio-net-pci,mac=$mac,type="${args[nic]}" )
    fi

    # To pass a USB device (e.g. a YubiKey for unlocking), add pass »--usb-port=${bus}-${port}«, where bus and port refer to the physical USB port »/sys/bus/usb/devices/${bus}-${port}« (see »lsusb -tvv«). E.g.: »--usb-port=3-1.1.1.4«
    if [[ ${args[usb-port]:-} ]] ; then local decl ; for decl in ${args[usb-port]//:/ } ; do
        qemu+=( -usb -device usb-host,hostbus="${decl/-*/}",hostport="${decl/*-/}" )
    done ; fi

    if [[ ${args[install]:-} == 1 ]] ; then local disk ; for disk in "${disks[@]}" ; do
        if [[ ! -e $disk ]] ; then args[install]=always ; fi
    done ; fi
    if [[ ${args[install]:-} == always ]] ; then
        local verbosity=--quiet ; if [[ ${args[trace]:-} ]] ; then verbosity=--trace ; fi ; if [[ ${args[debug]:-} ]] ; then verbosity=--debug ; fi
        hostPath=${hostPath:-} ${args[dry-run]:+echo} "$self" install-system "$diskImages" $verbosity --no-inspect || return
    fi

    qemu+=( "${argv[@]}" )
    if [[ ${args[dry-run]:-} ]] ; then
        echo "${qemu[@]}"
    else
        ( set -x ; "${qemu[@]}" ) || return
    fi

    # https://askubuntu.com/questions/54814/how-can-i-ctrl-alt-f-to-get-to-a-tty-in-a-qemu-session
}

declare-command add-bootkey-to-keydev blockDev << 'EOD'
Creates a random static key on a new key partition on the GPT partitioned »$blockDev«. The drive can then be used as headless but removable disk unlock method.
To create/clear the GPT beforehand, run: $ sgdisk --zap-all "$blockDev"
EOD
function add-bootkey-to-keydev {
    local blockDev=$1 ; local hostHash=${2:-@{config.networking.hostName!hashString.sha256}}
    local bootkeyPartlabel=bootkey-${hostHash:0:8}
    @{native.gptfdisk}/bin/sgdisk --new=0:0:+1 --change-name=0:"$bootkeyPartlabel" --typecode=0:0000 "$blockDev" || exit # create new 1 sector (512b) partition
    @{native.parted}/bin/partprobe "$blockDev" && @{native.systemd}/bin/udevadm settle -t 15 || exit # wait for partitions to update
    </dev/urandom tr -dc 0-9a-f | head -c 512 >/dev/disk/by-partlabel/"$bootkeyPartlabel" || exit
}

declare-command mount-keystore-luks cryptsetupOptions... << 'EOD'
Tries to open and mount the systems keystore from its LUKS partition. If successful, this also adds the traps to close the keystore when the parent shell exits (so this is not useful as a standalone »COMMAND«, use the »bash« or »--command« options).
For the exit traps to trigger on exit from the calling script / shell, this can't run in a sub shell (and therefore can't be called from a pipeline).
See »open-system«'s implementation for some example calls to this function.
EOD
function mount-keystore-luks {
    local keystore=keystore-@{config.networking.hostName!hashString.sha256:0:8}
    mkdir -p -- /run/$keystore && prepend_trap "[[ ! -e /run/$keystore ]] || rmdir /run/$keystore" EXIT || return
    @{native.cryptsetup}/bin/cryptsetup open "$@" /dev/disk/by-partlabel/$keystore $keystore && prepend_trap "@{native.cryptsetup}/bin/cryptsetup close $keystore" EXIT || return
    @{native.util-linux}/bin/mount -o nodev,umask=0077,fmask=0077,dmask=0077,ro /dev/mapper/$keystore /run/$keystore && prepend_trap "@{native.util-linux}/bin/umount /run/$keystore" EXIT || return
}

## Opens the keystore with the primary unlock method, which may not be convenient to use, but should always be defined.
function mount-keystore-luks-primary {
    local usage=luks/keystore-@{config.networking.hostName!hashString.sha256:0:8}/0
    local method=@{config.setup.keystore.keys[$usage]%%=*}
    local options=@{config.setup.keystore.keys[$usage]:$(( ${#method} + 1 ))}

    local attempt ; for attempt in 2 3 x ; do
        if mount-keystore-luks --key-file=<( gen-key-"$method" "$usage" "$options" ) ; then break ; fi
        if [[ $attempt == x ]] ; then \return 1 ; fi ; echo "Retrying ($attempt/3):"
    done
}

declare-command open-system diskImages << 'EOD'
Performs any steps necessary to mount the target system at »/tmp/nixos-install-@{config.networking.hostName}« on the current host.
For any steps taken, it also adds the steps to undo them on exit from the calling shell (so this is not useful as a standalone »COMMAND«, use the »bash« or »--command« options, and don't call this from a sub-shell that exits too early).
»diskImages« may be passed in the same format as to the installer. Any image files passed are ensured to be loop-mounted. »root« may also pass device paths.

Perfect to inspect/update/amend/repair a system's installation afterwards, e.g.:
$ install-system-to $mnt
$ nixos-install --system ${config_system_build_toplevel} --no-root-passwd --no-channel-copy --root $mnt
$ nixos-enter --root $mnt
EOD
function open-system {
    local diskImages=${1:-} # If »diskImages« were specified and they point at files that aren't loop-mounted yet, then loop-mount them now:
    local images=$( @{native.util-linux}/bin/losetup --list --all --raw --noheadings --output BACK-FILE )
    local decl ; for decl in ${diskImages//:/ } ; do
        local image=${decl/*=/} ; if [[ $image != /dev/* ]] && ! <<<$images grep -xF $image ; then
            local blockDev=$( @{native.util-linux}/bin/losetup --show -f "$image" ) && prepend_trap "@{native.util-linux}/bin/losetup -d '$blockDev'" EXIT || return
            @{native.parted}/bin/partprobe "$blockDev" || return
        fi
    done
    @{native.systemd}/bin/udevadm settle -t 15 || true # sometimes partitions aren't quite made available yet

    if [[ @{config.setup.keystore.enable} && ! -e /dev/mapper/keystore-@{config.networking.hostName!hashString.sha256:0:8} ]] ; then # Try a bunch of approaches for opening the keystore:
        mount-keystore-luks --key-file=<( printf %s "@{config.networking.hostName}" ) || # costs nothing to try
        mount-keystore-luks --key-file=/dev/disk/by-partlabel/bootkey-@{config.networking.hostName!hashString.sha256:0:8} || # costs nothing to try
        mount-keystore-luks-primary || # should always be applicable
        mount-keystore-luks --key-file=<( read -s -p PIN: pin && echo ' touch!' >&2 && @{native.yubikey-personalization}/bin/ykchalresp -2 "$pin" ) ||
        mount-keystore-luks || # (getting desperate)
        return # oh well
    fi

    export mnt=/tmp/nixos-install-@{config.networking.hostName} # allow this to leak into the calling scope
    if [[ ! -e $mnt ]] ; then mkdir -p "$mnt" && prepend_trap "rmdir '$mnt'" EXIT || return ; fi

    open-luks-layers || return # Load crypt layers and zfs pools:
    if [[ $( LC_ALL=C type -t import-zpools ) == 'function' ]] ; then import-zpools "$mnt" skipImported ; fi

    prepend_trap "unmount-system '$mnt'" EXIT && mount-system "$mnt" '' 1 || return
    df -h | grep $mnt | cat
}