CentOS 6 - Troubleshoot root disk not resized

Problem

Centos 6 Generic Cloud Image doesn't resize root partition accordingly

Centos 6 Generic Cloud Image

    $ lsblk
    NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
    sda      8:0    0  20G  0 disk
    `-sda1   8:1    0   8G  0 part /

Solution

Install all available updates

    sudo yum update -y

Install the EPEL helper package

    sudo yum install -y epel-release

Install cloud-init and dracut-modules-growroot

This has to be done after installing epel-release, because otherwise YUM won't look in the EPEL repository, where dracut-modules-growroot is available.

    sudo yum install -y cloud-init dracut-modules-growroot

Switch to root

    sudo su

Rebuild all initramfs images

This is very important. Without rebuilding the initramfs images, the module won't be available and nothing will get done.

    rpm -qa kernel | sed 's/^kernel-//'  | xargs -I {} dracut -f /boot/initramfs-{}.img {}

Reboot the VM

    reboot

Check the partition

    $ lsblk
    NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
    sda      8:0    0  20G  0 disk
    `-sda1   8:1    0  20G  0 part /