Importing Ubuntu 20.04 cloud images

Question

Following the instructions at https://docs.aws.amazon.com/vm-import/latest/userguide/vmimport-image-import.html.
Doing a
```
aws ec2 import-image --disk-containers Format=OVA,UserBucket="{S3Bucket=,S3Key=ubuntu-18.04-server-cloudimg-amd64.ova}"
```
Using the image at https://cloud-images.ubuntu.com/releases/bionic/release/ubuntu-18.04-server-cloudimg-amd64.ova, works as expected and the AMI is created fine.

But the same using https://cloud-images.ubuntu.com/releases/focal/release/ubuntu-20.04-server-cloudimg-amd64.ova, i.e the 20.04 image returns
```
ClientError: We were unable to read your import's initramfs/initrd to determine what drivers your import requires to run in EC2.
```
I know there are AMIs available with the Ubuntu 20.04, I am trying to understand what causes this error and how to overcome it in a custom OVA I am building.

TIA

Answer

I looked into this and I think I've figured out what's happening. Canonical made a change to their cloud images in which "server" versions no longer include microcode related packages:

https://bugs.launchpad.net/ubuntu/+source/debian-installer/+bug/1938588

The microcode packages, (amd64-microcode and intel-microcode) change the format of the initrd when they're installed. The file can either be a single CPIO archive or a 2-part CPIO archive with 1 part being compressed:

https://unix.stackexchange.com/questions/505746/content-of-initramfs

One of these formats can cause the import service to return a client error. There are 2 general approaches for working around the issue:

1) If you'd like to use the base image for Ubuntu 20, simply use a EC2 ready AMI from Canonical. They publish their AMI account number to make it easy to find these official images: 
https://ubuntu.com/server/docs/cloud-images/amazon-ec2

2) If you have an existing image that has content and modifications you'd like to import, I would try to rebuild the initrd files by installing the microcode packages. Make sure to have a backup first, but then you can attempt to install the microcode packages:

sudo apt-get install -y dracut-core amd64-microcode intel-microcode

After the microcode packages are added the initrd should rebuild automatically in the correct format and resolve the issue, allowing the import to complete normally.

Importing Ubuntu 20.04 cloud images

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