pkgs/tools/filesystems/bees/bees-service-wrapper

   1 #!/usr/bin/env bash
   2
   3 shopt -s extglob
   4
   5 # Upstream wrapper requires UUID to be used for configuration.
   6
   7 # However, when declaratively describing a host, we may not know its UUID, and
   8 # shouldn't need to persist something that will differ between hosts built from
   9 # the same configuration template.
  10
  11 # Thus, for using bees from NixOS, we have our own wrapper, which supports not
  12 # just UUID but any specification permitted by findmnt
  13
  14 [[ $bees_debug ]] && { PS4=':${BASH_SOURCE##*/}:$LINENO+'; set -x; }
  15
  16 usage() {
  17   cat >&2 <<EOF
  18 Usage: ${BASH_SOURCE##*/} run|cleanup config-name|fsSpec [idxSizeMB=...] [verbosity=...] [workDir=...] [-- daemon-options...]
  19
  20   fsSpec should be in a format recognized by findmnt. Alternately,
  21   "config-name" may refer to a file that exists in ${bees_config_dir:-/etc/bees}
  22   with a .conf extension; if that file does not specify UUID, findmnt will be
  23   used in addition.
  24
  25   Note that while config files may presently use shell arithmetic, use of this
  26   functionality is not encouraged going forward: Setting ''idxSizeMB=4096'' is
  27   preferred over ''DB_SIZE=$((1024*1024*1024*4))'' or ''DB_SIZE=$(( AL16M * 256 ))'',
  28   although both of these are presently supported.
  29
  30   If fsSpec contains a /, it assumed to be a mount point to be looked up by
  31   findmnt, not a config file name.
  32
  33   daemon-options are passed directly through to the daemon on startup, as
  34   documented at https://github.com/Zygo/bees/blob/master/docs/options.md.
  35 EOF
  36   exit 1
  37 }
  38
  39 die() { echo "$*" >&2; exit 1; }
  40
  41 allConfigNames=( blockdev fsSpec home idxSize idxSizeMB mntDir runDir status verbosity workDir )
  42
  43 # Alternate names for configuration values; "bees_" will always be prepended
  44 declare -A altConfigNames=(
  45   # from original bees wrapper
  46   [BEESHOME]=home
  47   [BEESSTATUS]=status
  48   [MNT_DIR]=mntDir
  49   [UUID]=uuid
  50   [WORK_DIR]=runDir
  51   [DB_SIZE]=idxSize
  52 )
  53
  54 # legacy bees config files can be arbitrary shell scripts, so we need to actually evaluate them
  55 sandboxedConfigFileEval() {
  56   bash_exe=$(type -P bash) || exit
  57   PATH=/var/empty ENV='' BASH_ENV='' AL128K="$((128*1024))" AL16M="$((16*1024*1024))" "$bash_exe" -r ${bees_debug+-x} \
  58     -c 'eval "$(</dev/stdin)" >&2; for var; do [[ ${!var} ]] && printf "%q=%s\\0" "$var" "${!var}"; done' \
  59     "${!altConfigNames[@]}" "${allConfigNames[@]}" \
  60     <"$1"
  61 }
  62
  63 readConfigFileIfExists() {
  64   local line
  65   [[ -s $1 ]] || return 1
  66   while IFS= read -r -d '' line; do
  67     line=${line%%+([[:space:]])"#"*}
  68     [[ $line ]] || continue
  69     [[ $line = *=* ]] || {
  70       printf 'WARNING: Config file line not recognized: %q\n' "$line" >&2
  71       continue
  72     }
  73     set_option "$line"
  74   done < <(sandboxedConfigFileEval "$1")
  75 }
  76
  77 set_option() {
  78   local k v
  79   k="${1%%=*}" v="${1#*=}"
  80   [[ ${altConfigNames[$k]} ]] && k=${altConfigNames[$k]}
  81   printf -v "bees_$k" %s "$v"
  82 }
  83
  84 uuid_re='^[[:xdigit:]]{8}-[[:xdigit:]]{4}-[[:xdigit:]]{4}-[[:xdigit:]]{4}-[[:xdigit:]]{12}$'
  85
  86 # Shared code for setting configuration used by other operations.
  87 #
  88 # Reads from global associative array "opts" containing options passed in as
  89 # key=value pairs on the command line, looks for config-file overrides, and
  90 # sets individual global variables.
  91 _setup() {
  92   declare fstype
  93   bees_fsSpec=$1; shift
  94
  95   # Look for file-based configuration, additional to honoring configuration on the command line
  96   bees_config_dir="${bees_config_dir:-/etc/bees}"
  97   if [[ $bees_fsSpec =~ $uuid_re ]]; then
  98     bees_uuid=$bees_fsSpec
  99     # If our spec looks like a bare UUID, and no config file exists in the new
 100     # format, fall back to legacy config file search mechanism (grep; ewww).
 101     if ! readConfigFileIfExists "$bees_config_dir/UUID=$bees_fsSpec.conf"; then
 102       # Legacy approach to finding a config file: Grep for a *.conf file
 103       # containing the UUID within its text. Permitting spaces around the "="
 104       # appears to be a bug, but is retained for compatibility with the
 105       # original upstream script.
 106       allConfFiles=( "$bees_config_dir"/*.conf )
 107       if (( ${#allConfFiles[@]} )); then
 108         # in read or readarray with -d '', the NUL terminating the empty string is used as delimiter character.
 109         readarray -d '' -t matchingConfFiles < <(grep -E -l -Z "^[^#]*UUID[[:space:]]*=[[:space:]]*" "${allConfFiles[@]}")
 110       else
 111         matchingConfFiles=( )
 112       fi
 113       if (( ${#matchingConfFiles[@]} == 1 )); then
 114         # Exactly one configuration file exists in our target directory with a reference to the UUID given.
 115         bees_config_file=${matchingConfFiles[0]}
 116         readConfigFileIfExists "$bees_config_file"
 117         echo "NOTE: Please consider renaming $bees_config_file to $bees_config_dir/UUID=$bees_fsSpec" >&2
 118         echo "      ...and passing UUID=$bees_fsSpec on startup." >&2
 119       elif (( ${#matchingConfFiles[@]} > 1 )); then
 120         # The legacy wrapper would silently use the first file and ignore
 121         # others, but... no.
 122         echo "ERROR: Passed a bare UUID, but multiple configuration files match it:" >&2
 123         printf ' - %q\n' "${matchingConfFiles[@]}" >&2
 124         die "Unable to continue."
 125       fi
 126     fi
 127   else
 128     # For a non-UUID fsSpec that is not a path, look only for a config file
 129     # exactly matching its text.
 130     #
 131     # (Passing a mount point as a fsSpec is only supported with the new
 132     # wrapper; all key=value pairs can be passed on the command line in this
 133     # mode, so config file support is not needed).
 134     [[ $bees_fsSpec = */* ]] || readConfigFileIfExists "$bees_config_dir/$bees_fsSpec.conf"
 135   fi
 136
 137   [[ $bees_uuid ]] || {
 138     # if bees_uuid is not in our .conf file, look it up with findmnt
 139     for findmnt_mode in --kernel --mtab --fstab; do
 140       read -r bees_uuid fstype < <(findmnt "$findmnt_mode" -n -o uuid,fstype "$bees_fsSpec") ||:
 141       [[ $bees_uuid && $fstype ]] && break
 142     done
 143     [[ $bees_uuid ]] || die "Unable to identify a device matching $bees_fsSpec with findmnt"
 144     [[ $fstype = btrfs ]] || die "Device type is $fstype, not btrfs"
 145   }
 146
 147   [[ $bees_uuid = */* ]] || readConfigFileIfExists "$bees_config_dir/UUID=$bees_uuid.conf"
 148
 149   # Honor any values read from config files above; otherwise, set defaults.
 150   bees_workDir="${bees_workDir:-.beeshome}"
 151   bees_runDir="${bees_runDir:-/run/bees}"
 152   bees_mntDir="${bees_mntDir:-$bees_runDir/mnt/$bees_uuid}"
 153   bees_home="${bees_home:-$bees_mntDir/$bees_workDir}"
 154   bees_status="${bees_status:-${bees_runDir}/$bees_uuid.status}"
 155   bees_verbosity="${bees_verbosity:-6}"
 156   bees_idxSizeMB="${bees_idxSizeMB:-1024}"
 157   bees_idxSize=${bees_idxSize:-"$(( bees_idxSizeMB * 1024 * 1024 ))"}
 158   bees_blockdev=${bees_blockdev:-"/dev/disk/by-uuid/$bees_uuid"}
 159
 160   [[ -b $bees_blockdev ]] || die "Block device $bees_blockdev missing"
 161   (( bees_idxSize % (16 * 1024 * 1024) == 0 )) || die "DB size must be divisible by 16MB"
 162 }
 163
 164 do_run() {
 165   local db old_db_size
 166
 167   _setup "$1"; shift
 168   mkdir -p -- "$bees_mntDir" || exit
 169
 170   # subvol id 5 is reserved for the root subvolume of a btrfs filesystem.
 171   mountpoint -q "$bees_mntDir" || mount -osubvolid=5 -- "$bees_blockdev" "$bees_mntDir" || exit
 172   if [[ -d $bees_home ]]; then
 173     btrfs subvolume show "$bees_home" >/dev/null 2>&1 || die "$bees_home exists but is not a subvolume"
 174   else
 175     btrfs subvolume create "$bees_home" || exit
 176     sync # workaround for Zygo/bees#93
 177   fi
 178   db=$bees_home/beeshash.dat
 179   touch -- "$db"
 180
 181   old_db_size=$(stat -c %s -- "$db")
 182   new_db_size=$bees_idxSize
 183
 184   if (( old_db_size != new_db_size )); then
 185     rm -f -- "$bees_home"/beescrawl."$bees_uuid".dat
 186     truncate -s "$new_db_size" -- "$db" || exit
 187   fi
 188   chmod 700 -- "$bees_home"
 189
 190   # BEESSTATUS and BEESHOME are the only variables handled by the legacy
 191   # wrapper for which getenv() is called in C code.
 192   BEESSTATUS=$bees_status BEESHOME=$bees_home exec "${beesd_bin:-/lib/bees/bees}" \
 193     --verbose "$bees_verbosity" \
 194     "$@" "$bees_mntDir" || exit
 195 }
 196
 197 do_cleanup() {
 198   _setup "$1"; shift
 199   mountpoint -q "$bees_mntDir" && umount -l -- "$bees_mntDir" || exit
 200 }
 201
 202 (( $# >= 2 )) || usage
 203 declare -f "do_$1" >/dev/null 2>&1 || usage
 204 mode=$1; shift # must be a do_* function; currently "run" or "cleanup"
 205
 206 declare -a args=( "$1" ); shift  # pass first argument (config-name|fsSpec) through literally
 207
 208 # parse other arguments as key=value pairs, or pass them through literally if they do not match that form.
 209 # similarly, any option after "--" will be passed through literally.
 210 while (( $# )); do
 211   if [[ $1 = *=* ]]; then
 212     set_option "$1"
 213   elif [[ $1 = -- ]]; then
 214     shift
 215     args+=( "$@" )
 216     break
 217   else
 218     args+=( "$1" )
 219   fi
 220   shift
 221 done
 222
 223 "do_$mode" "${args[@]}"