Google cloud after VM Import no free space available on root drive - import

Question

I created a Postgres server locally using virualbox using Ubuntu 16.04. Using the import tool to move it to Google cloud seemed to work fine, but the root drive shows 100% full. None of the disk expansion instructions (including creating a snapshot and recreating the boot drive) seem to make any space available.
There seems to be a boot drive and a root drive. But the root drive shows it is all used. The boot drive shows space available, but it should be 15G in size not 720M.
Filesystem Size Used Avail Use% Mounted on
udev 1.8G 0 1.8G 0% /dev
tmpfs 370M 5.3M 365M 2% /run
/dev/mapper/techredo--vg-root 2.5G 2.5G 0 100% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/sdb1 720M 121M 563M 18% /boot
tmpfs 370M 0 370M 0% /run/user/406485188

Answer 1

I checked if is possible to use LVM in GCP instances, and I find out that you're free to use it but is not supported by Google Cloud since instances doesn't use LVM by default.
On the other hand, you need to make sure that the Linux Guest Environment is installed in your instance, so you can get the automatic resizing feature. Please follow this guide to learn how to validate: https://cloud.google.com/compute/docs/images/install-guest-environment#wgei
Since your root partition is full and you're not able to install more programs I suggest you 2 workarounds:
Workaround 1: Create a new VirtualBox VM with and import it again, please note that your root partition is pretty small (2.5G) so I suggest you next time create a partition with at least 10GB, and avoid use LVM during the installation.
After your instance is ready in GCP, please check if the Linux Guest Environment is installed in your instance, if not install it: https://cloud.google.com/compute/docs/images/install-guest-environment
Workaround 2: Check which directory is causing problems and then which files are consuming your disk space, delete them to gain space, install the Guest enviroment and try to resize your instance.
a) To check the directories and files sizes, follow these steps:
There are several tools that can display your disk usage graphically but since your root partition is full you'll have to get the information by running commands (old school style).
Please follow these steps:
Please go to the root directory:
cd /
Please run this command to get the size of the main subdirectories under the root partition:
sudo du -aBM -d 1 . -R | sort -nr | head -20
NOTE: Identify which directory is eating your root partition.
Please run this command to get a full list of the files and its sizes:
du -k *| sort -nr | cut -f2 | xargs -d '\n' du -sh
NOTE: The above command will display all files and directories too fast, so in order to scroll down slowly, please run the same command adding the "less" instruction:
du -k *| sort -nr | cut -f2 | xargs -d '\n' du -sh |less
Press the spacebar to scroll down.
Please keep in mind that you have to go to the directory you want to analyze before running the commands in step 3 or 4 (just in case you want to analyze another directory).
Additional to this you can run the command "apt-get clean" to clear the downloaded packages (.deb files) that usually consumes a high part of your disk.
b) To resize your instance, you have 2 options:
Resize your VM instance "primary-server" by following this guide[1].
NOTE: The steps included in this option are pretty easy to follow, if this doesn't work try the second option which requires advanced Linux abilities.
Create a snapshot from the VM instance "primary-server".
2.1 Create a new instance based on a Linux distribution.
2.2 Once it's been created, stop the instance.
2.3 Follow this guide to add an additional disk[2].
NOTE: Basically you have to edit the instance "primary-server" and add an additional disk, don't forget to select the snapshot option from the "Source type" list and click on the snapshot you just created.
2.4 Start the instance.
2.5 Mount the disk by following this guide[3].
NOTE: Please skip step 4. The additional disk it's actually a boot disk so it's been already formatted. So, don't apply the format to it; just mount it, .
2.6 Check the permissions of the file "/etc/fstab".
NOTE: The permissions should be "-rw-r--r--" and the owner "root"
2.6.1 Delete files to reduce the disk size.
2.7 Unmount the disk at OS level.
2.8 Stop the instance.
2.9 Detach the additional disk from the new instance in GCP.
NOTE: Please follow this guide[4] and instead of clicking on X next to the boot disk, please click on X next to the additional disk.
2.10 Create a new instance and instead of using an image in the "boot disk" section, please use the disk you just restored.
NOTE: For this please go to the "Boot disk" section and click on the "Change" button, then go to the "Existing" TAB and select the disk you just restored.
REFERENCES:
[1] https://cloud.google.com/compute/docs/disks/add-persistent-disk#inaccessible_instance
[2] https://cloud.google.com/compute/docs/disks/add-persistent-disk#create_disk
[3] https://cloud.google.com/compute/docs/disks/add-persistent-disk#formatting
[4] https://cloud.google.com/compute/docs/disks/detach-reattach-boot-disk#detach_disk
Please let me know the results.