Expand/Resize Root Partition Upon First Boot Via Cloud-init

[Tarkan Erimer @F-Secure]

Hi all,

For some time we're trying to make HVM images to expand their root partition size upon first boot via cloud-init and cloud-initramfs-growpart on Debian 7 without success. After launching the instance, it just attaches a secondary disk with the requested size (m1.small:5GB) instead of expanding the disk to 5 GB. The initial image is 1GB in size and we want it to be expanded upon first boot depending on the requested size (m1.small etc.) at launch time. 

Our setup is :

1. Create an image file via "dd if=/dev/zero of=${IMAGE} bs=1M count=1024"
2. Partition, format and mount the disk image via :

          parted -s ${IMAGE} mklabel msdos

          parted -a optimal ${IMAGE} mkpart primary 0% 100%

          parted -s ${IMAGE} set 1 boot on

          install-mbr ${IMAGE}

          BASE_DEVICE=`sudo losetup -f --show ${IMAGE}`

          DEVICE=`sudo losetup -o 0 -f --show ${BASE_DEVICE}`

          sudo mkfs.ext4 -F -m 0 ${DEVICE}

          sudo tune2fs -i 0 -c 0 -L rootfs ${DEVICE}

          [ -d ${TARGET} ] || mkdir ${TARGET}

          sudo mount -o loop ${DEVICE} ${TARGET}

      3. Then, perform "debootstrap" to install Debian 7 and perform some tweaks/config changes within the debootstrapped Debian 7 image.

      4. Finally; upload, register and launch the image via :

              euca-install-image -i ${IMAGE} -n ${NAME} -r x86_64 --virtualization-type hvm -b ${NAME} -u ${EC2_USER_ID}

              euca-run-instances -k abc -g abc-group -t m1.small emi-9999999

Also, cloud-init and cloud-initramfs-growpart installed and configure with the following settings within the image :

#cloud-config

# The top level settings are used as module and system configuration.

# A set of users which may be applied and/or used by various modules when a 'default' entry is found it will reference the 'default_user' from the distro configuration 

# specified below

users:

   - default

# If this is set, 'root' will not be able to ssh in and they will get a message to login instead as the above $user (ubuntu)

disable_root: true

# This will cause the set+update hostname module to not operate (if true)

preserve_hostname: false

# Enable hosts file management

manage_etc_hosts: True

# The modules that run in the 'init' stage

cloud_init_modules:

 - migrator

 - bootcmd

 - write-files

 - growpart

 - resizefs

 - set_hostname

 - update_hostname

 - update_etc_hosts

 - ca-certs

 - rsyslog

 - users-groups

 - ssh

# The modules that run in the 'config' stage

cloud_config_modules:

# Emit the cloud config ready event this can be used by upstart jobs for 'start on cloud-config'.

 - emit_upstart

 - mounts

 - locale

 - set-passwords

 - grub-dpkg

 - apt-pipelining

 - apt-configure

 - package-update-upgrade-install

 - timezone

 - puppet

 - chef

 - salt-minion

 - mcollective

 - disable-ec2-metadata

 - runcmd

# The modules that run in the 'final' stage

cloud_final_modules:

 - rightscale_userdata

 - scripts-per-once

 - scripts-per-boot

 - scripts-per-instance

 - scripts-user

 - ssh-authkey-fingerprints

 - keys-to-console

 - phone-home

 - final-message

 - power-state-change

A side note : cloud-init "datasource" was configured only for "EC2". All other options de-selected. 

So, what's the proper way of doing it and/or what are we missing ? I did search on the net and on Eucalyptus web page without luck. Any pointers/documents will be highly appreciated. 

Thanks,

Tarkan