clone & resize Ubuntu Cloud image from 2GB to 40GB in 2 seconds

ubuntu lvm clone-resize

# time ./do-all.sh
+ lvcreate -kn -s -n ubunt2 /dev/k2/ubunt
  Logical volume "ubunt2" created
+ lvresize -L 40G /dev/k2/ubunt2
  Extending logical volume ubunt2 to 40.00 GiB
  Logical volume ubunt2 successfully resized
+ echo -en 'd\nn\np\n\n\n\n\n\nw\nq\n'
+ fdisk /dev/k2/ubunt2

Command (m for help): Selected partition 1

Command (m for help): Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): Partition number (1-4, default 1): Using default value 1
First sector (2048-83886079, default 2048): Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-83886079, default 83886079): Using default value 83886079

Command (m for help): Command (m for help): Command (m for help): The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
+ true
+ kpartx -a /dev/k2/ubunt2
+ '[' '!' -L /dev/mapper/k2-ubunt2p1 ']'
+ sleep 0.1
+ '[' '!' -L /dev/mapper/k2-ubunt2p1 ']'
+ sleep 0.1
+ '[' '!' -L /dev/mapper/k2-ubunt2p1 ']'
+ resize2fs /dev/mapper/k2-ubunt2p1
resize2fs 1.42.10 (18-May-2014)
Resizing the filesystem on /dev/mapper/k2-ubunt2p1 to 10485504 (4k) blocks.
The filesystem on /dev/mapper/k2-ubunt2p1 is now 10485504 blocks long.

+ kpartx -d /dev/k2/ubunt2

real    0m1.986s