Only use tmpfs if build machine has 4GB+ RAM.

For machines with low RAM (or no access to /proc/meminfo) the builder
will still run, but will just build inside the filesystem that is
hosting /tmp. This will result in a slower build (especially if there
are a lot of .deb packages installed).

Fixes bug #1175453

Change-Id: I79f2672058c11e377548820df0ab4fad8f47ffdc

README.md

@@ -293,6 +293,19 @@ It's a colon (:) separated path list, and it will work in a first path/element f
 first served approach. The included elements tree is used when no path is supplied,
 and is added to the end of the path if a path is supplied.
 
+Requirements
+============
+
+If you have 4GB of available physical RAM\*, or more, diskimage-builder will
+create a tmpfs mount to build the image in. This will improve image build time
+by building in RAM. This can be disabled completely by passing --no-tmpfs to
+disk-image-create. ramdisk-image-create does not use a tmpfs mount. If tmpfs
+is not used, you will need enough room in /tmp to store two uncompressed
+cloud images. If you do have tmpfs, you will still need /tmp space for one
+uncompressed cloud image and about 20% of that for working files.
+
+\* As reported by /proc/meminfo MemTotal
+
 Copyright
 =========
 

bin/disk-image-create

@@ -39,6 +39,7 @@ function show_options () {
     echo "    -c -- clear environment before starting work"
     echo "    -n skip the default inclusion of the 'base' element"
     echo "    -p package[,package,package] -- list of packages to install in the image"
+    echo "    --no-tmpfs -- do not use tmpfs to speed image build"
     echo
     echo "ELEMENTS_PATH will allow you to specify multiple locations for the elements."
     exit 0
@@ -46,7 +47,7 @@ function show_options () {
 
 INSTALL_PACKAGES=""
 COMPRESS_IMAGE="true"
-TEMP=`getopt -o a:ho:xucnp: -n $SCRIPTNAME -- "$@"`
+TEMP=`getopt -o a:ho:xucnp: -l no-tmpfs -n $SCRIPTNAME -- "$@"`
 if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi
 
 # Note the quotes around `$TEMP': they are essential!
@@ -62,6 +63,7 @@ while true ; do
         -c) shift ; export CLEAR_ENV=1;;
         -n) shift; export SKIP_BASE="1";;
         -p) IFS="," read -a INSTALL_PACKAGES <<< "$2"; export INSTALL_PACKAGES ; shift 2 ;;
+        --no-tmpfs) shift; export DIB_NO_TMPFS=1;;
         --) shift ; break ;;
         *) echo "Internal error!" ; exit 1 ;;
     esac

lib/common-functions

@@ -13,10 +13,21 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+function tmpfs_check() {
+  [ "$DIB_NO_TMPFS" == "0" ] || return 1
+  [ -r /proc/meminfo ] || return 1
+  total_kB=$(awk '/^MemTotal/ { print $2 }' /proc/meminfo)
+  [ $total_kB -lt $((4*1024*1024)) ] || return 0
+  echo "Not enough RAM to use tmpfs for build. ($total_kB < 4G)"
+  return 1
+}
+
 function mk_build_dir () {
   export TMP_BUILD_DIR=$(mktemp -t -d --tmpdir=${TMP_DIR:-/tmp} image.XXXXXXXX)
   [ $? -eq 0 ] || die "Failed to create tmp directory"
-  sudo mount -t tmpfs tmpfs $TMP_BUILD_DIR
+  if tmpfs_check ; then
+    sudo mount -t tmpfs tmpfs $TMP_BUILD_DIR
+  fi
   sudo chown $(id -u):$(id -g) $TMP_BUILD_DIR
   trap cleanup EXIT
   echo Building in $TMP_BUILD_DIR

lib/img-defaults

@@ -38,6 +38,7 @@ FS_TYPE=${FS_TYPE:-ext4}
 IMAGE_TYPE=${IMAGE_TYPE:-qcow2}
 IMAGE_NAME=${IMAGE_NAME:-image}
 export DIB_IMAGE_SIZE=${DIB_IMAGE_SIZE:-2} # N.B. This size is in GB
+export DIB_NO_TMPFS=${DIB_NO_TMPFS:-0}
 # Set via the CLI normally.
 # IMAGE_ELEMENT=
 _BASE_ELEMENT_DIR=$(dirname $0)/../elements

lib/img-functions

@@ -41,7 +41,7 @@ function cleanup () {
 function cleanup_dirs () {
     sudo rm -rf $TMP_BUILD_DIR/built
     sudo rm -rf $TMP_BUILD_DIR/mnt
-    sudo umount $TMP_BUILD_DIR
+    sudo umount -f $TMP_BUILD_DIR || true
     rm -rf $TMP_BUILD_DIR
 }
 

lib/ramdisk-defaults

@@ -24,3 +24,4 @@ IMAGE_NAME=${IMAGE_NAME:-"ramdisk"}
 _BASE_ELEMENT_DIR=$(dirname $0)/../elements
 ELEMENTS_PATH=${ELEMENTS_PATH:+"$ELEMENTS_PATH:$_BASE_ELEMENT_DIR"}
 export ELEMENTS_PATH=${ELEMENTS_PATH:-$_BASE_ELEMENT_DIR}
+export DIB_NO_TMPFS=${DIB_NO_TMPFS:-1}

lib/ramdisk-functions

@@ -25,6 +25,7 @@ function fullpath() {
 }
 
 function cleanup () {
+  sudo umount -f $TMP_BUILD_DIR || true
   rm -rf "$TMP_BUILD_DIR"
 }
 

sudoers.d/img-build-sudoers

@@ -54,5 +54,5 @@ ALL ALL=(root) NOPASSWD: /sbin/losetup -d /dev/loop*
 ALL ALL=(root) NOPASSWD: /sbin/partprobe /dev/loop*
 ALL ALL=(root) NOPASSWD: /usr/bin/du --block-size=* -x -s /tmp/*/built
 ALL ALL=(root) NOPASSWD: /bin/mount -t tmpfs tmpfs /tmp/image.*
-ALL ALL=(root) NOPASSWD: /bin/umount /tmp/image.*
+ALL ALL=(root) NOPASSWD: /bin/umount -f /tmp/image.*
 ALL ALL=(root) NOPASSWD: /bin/chown *\:* /tmp/image.*