Write zeros to disk to improve disk compression

Write zeros to a file on the root partition until the filesystem is
full, then unlink the file. Packer will compress the disk as part of
the build, resulting in smaller final disk image.

1 files changed, 6 insertions, 0 deletions

diff --git a/provision/cleanup.sh b/provision/cleanup.sh
index b8a2336..29da429 100644..100755
--- a/provision/cleanup.sh
+++ b/provision/cleanup.sh
@@ -4,3 +4,9 @@ set -e
 set -x
 
 yes | sudo pacman -Scc
+
+# Write zeros to improve virtual disk compaction.
+zerofile=$(/usr/bin/mktemp /zerofile.XXXXX)
+dd if=/dev/zero of="$zerofile" bs=1M || true
+rm -f "$zerofile"
+sync