build_pxe_stick.sh

#!/bin/bash
set -e
shopt -s nullglob


function log() {
    echo -e "\e[32m$*\e[0m" >&2
}

function warn() {
    echo -e "\e[33m$*\e[0m" >&2
}

function error() {
    echo -e "\e[31m$*\e[0m" >&2
}

function happy_grep() {
    grep "$@" || :
}

declare -A ENV2PREFIX=(
    [LOGEXPORT_HOST]=LOGEXPORT_
    [LOGEXPORT_PORT]=LOGEXPORT_
    [HEARTBEAT_URL]=HEARTBEAT_
    [NODE_HOSTNAME]=NODE_HOSTNAME
)

declare -A PREFIX2SVC=(
    [LOGEXPORT_]="Log Export"
    [HEARTBEAT_]="Heartbeat"
    [NODE_HOSTNAME]="hostname setting"
)

function check_env_vars() {
    for e in "${!ENV2PREFIX[@]}"; do
        prefix="${ENV2PREFIX[$e]}"
        svc="${PREFIX2SVC[$prefix]}"

        if [[ -z "${!e}" ]]; then
            warn "$e not set. Disabling $svc functionality from resultant system."
            unset_many "$prefix"
        fi
    done
}

function unset_many() {
    prefix="${1?}"
    log "unsetting $prefix* vars"

    mapfile -d '' vars < <(env -0)

    for v in "${vars[@]}"; do
        varname="${v%%=*}"
        if [[ "$varname" =~ "$prefix"* ]]; then
            warn "unsetting $varname"
            unset "$varname"
        fi
    done
}

function git_reference() {
    repo="$(
        git remote show -n origin \
        | grep "Fetch URL:" \
        | cut -d: -f2,3 \
        | tr -d " " \
        | sed "s/git@github/github/" \
        | sed "s|github.com:|github.com/|" \
        | sed "s|^github.com|https://github.com|" \
        | sed "s/.git$//"
        )"
    maybe_dirty=""
    if [[ -n "$(cd "$HERE"; git status --short)" ]]; then
        maybe_dirty=" (with uncommitted changes)"
    fi
    commit="$(cd "$HERE"; git rev-parse --short HEAD || echo "???")" 

    echo "$repo/tree/$commit$maybe_dirty"
}

function repro() {
    echo "#!/bin/bash"
    echo "# @ $(git_reference)"
    env_patterns=(
        -e "^K3S_"
        -e "^LOGEXPORT_"
        -e "^HEARTBEAT_"
        -e "^NAMECHEAP_DDNS_"
    )
    echo "env \\"
    for e in $(env | grep "${env_patterns[@]}" | cut -d= -f1); do
        printf "  %s=%q \\" "$e" "${!e}"
        echo # newline
    done
    echo "  $0"
}

function prep_ipxe() {
    (
        set -e
        cd "$OUT"
        git clone git://git.ipxe.org/ipxe.git
        cd ipxe/src
        # enable https because it isn't the 90s anymore
        sed -i \
            "s/#undef\\s\\+DOWNLOAD_PROTO_HTTPS/#define DOWNLOAD_PROTO_HTTPS/" \
            ./config/general.h
    ) >&2
    echo "$OUT/ipxe/src"
}

function build_uefi_ipxe() {
    (
        set -e
        cd "$1"
        bash "$HERE/mk_ipxe_script.sh" >"$1/generated.ipxe"
        make -j "$(nproc)" bin-x86_64-efi/ipxe.efi EMBED="$1/generated.ipxe"
        log "Built $PWD/bin-x86_64-efi/ipxe.efi"
    ) >&2
    echo "$1/bin-x86_64-efi/ipxe.efi"
}

function build_bios_ipxe() {
    (
        set -e
        cd "$1"
        bash "$HERE/mk_ipxe_script.sh" >"$1/generated.ipxe"
        make -j "$(nproc)" bin/ipxe.usb EMBED="$1/generated.ipxe"
        log "Built $PWD/bin/ipxe.usb"
    ) >&2
    echo "$1/bin/ipxe.usb"
}

function unmount() {
    log "unmounting $DISK (and associated partitions)"
    umount -q "$DISK" "$DISK"? || :
}

function usage_and_die() {
    error 'Usage: '
    error ' [SSH_KEY_PATH=/root/.ssh/id_rsa.pub] \\'
    error ' [NODE_HOSTNAME=node0] \\'
    error ' [LOGEXPORT_HOST=logsX.papertrailapp.com LOGEXPORT_PORT=XXXXX] \\'
    error ' [HEARTBEAT_URL=https://nudge.me/im_alive] \\'
    error ' [K3S_ENV_VARS_YOU_WANT_TO_SET=blahblahblah...] \\'
    error ' ./build_pxe_stick.sh /dev/sdX'
    error ''
    error 'If the necessary variables are not populated for a given component,'
    error 'then that functionality will be disabled in the resultant system,'
    error 'e.g., no LOGEXPORT_PORT, then log exporting will not be enabled.'
    exit 1
}

function mount_part() {
    root="$1"
    device="$2"
    name="$3"

    mkdir "$root/${name}_mnt"
    log "mounting $name volume @ $root/${name}_mnt"
    mount "$device" "$root/${name}_mnt"
    echo "$root/${name}_mnt"
}

HERE="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
OUT="$(mktemp -d /tmp/pxe_build_ephemeros_XXXXXX)"
log "Using $OUT for temp storage"

DISK="$1"
if [[ -z "$DISK" ]]; then
    usage_and_die
fi
check_env_vars

if [[ ! -w "$DISK" ]]; then
    error "$DISK is not writeable. Check your privilege, and that it exists."
    exit 2
fi

log "$DISK presently looks like this:"
log "$(lsblk "$DISK")"
read -p "We're gonna zap <$DISK>! Type \"i don't want that data\" to continue. >>> "
if [[ "$REPLY" != "i don't want that data" ]]; then
    error "Aborting."
    exit 2
fi

unmount

IPXE_PATH="$(prep_ipxe)"
UEFI_IPXE="$(build_uefi_ipxe "$IPXE_PATH")"
BIOS_IPXE="$(build_bios_ipxe "$IPXE_PATH")"

log "zeroing the first meg of $DISK"
dd if=/dev/zero of="$DISK" bs=1M count=1

log "Creating disk label for $DISK"
parted "$DISK" mklabel gpt 

log "dd'ing bios image to $DISK"
dd if="$BIOS_IPXE" of="$DISK"

log "Adding a partition for EFI boot to $DISK"
parted "$DISK" mkpart primary fat32 4MB 512MB
log "Adding a partition for secrets to $DISK"
parted "$DISK" mkpart primary ext4 512MB 1GB
partprobe

mkfs.fat -F32 -n efi "${DISK}1"
mkfs.ext4 -L secrets "${DISK}2"

EFI="$(mount_part "$OUT" "${DISK}1" efi)"
log "Writing ipxe.efi to efi partition"
mkdir -p "$EFI/efi/boot"
cp "$UEFI_IPXE" "$OUT/efi_mnt/efi/boot/bootx64.efi"

SECRETS="$(mount_part "$OUT" "${DISK}2" secrets)"
log "Writing environment files in $SECRETS..."
(
    umask 0077
    # NOTE: if you update these, also update the patterns in `repro`
    env | happy_grep "^K3S_" > "$SECRETS/k3s_env" 
    env | happy_grep "^LOGEXPORT_" > "$SECRETS/logexport_env"
    env | happy_grep "^HEARTBEAT_" > "$SECRETS/heartbeat_env"
    env | happy_grep "^NAMECHEAP_DDNS_" > "$SECRETS/namecheap_ddns_env"

    repro > "$SECRETS/reproduce.sh"
)

log "!! DONE !!"