How to create an image from scratch

Creating Images - Overview

Scaleway provides you a wide selection of operation system images and InstantApps, however sometimes you want to customize an image more or have needs for some specific configurations. In this case you can create your own image from scratch.

Requirements

Important: Images for X86_64 instances, must be bootable using UEFI. This means that the partition table must be of the GPT format and that the first partition is of EFI System partition type containing the EFI boot files.

Serving the Cloud Image

1 . Start a DEV1-S instance and install the required package so it can act as an web server for the cloud image. You can either start it from the console or using the Scaleway CLI:

scw instance server create name=image-server image=ubuntu_focal

2 . Once the instance is available, update the apt package repositories, install the following packages, and download the cloud image. In this tutorial we download the Ubuntu Focal Fossa Cloud Image:

apt update
apt -y install nginx p7zip libguestfs-tools
wget https://cloud-images.ubuntu.com/focal/current/focal-server-cloudimg-amd64-disk-kvm.img

3 . Use guestfishto adapt the image to your needs. The --network option is only required if you intend to install packages from the internet :

Important: It is important to add the Scaleway specific ecosystem which is availble as .deb and .rpm packages.

guestfish -a focal-server-cloudimg-amd64-disk-kvm.img --network
 
Welcome to guestfish, the guest filesystem shell for
editing virtual machine filesystems and disk images.                                                                                                                                                              
                                                                                                                                                                                                                    
Type: ‘help’ for help on commands                                                                                                                                                                                 
      ‘man’ to read the manual                                                                                                                                                                                    
      ‘quit’ to quit the shell
                                                                                                                                                                                                                    
<fs> run                                                                                                                                                                                                         
 100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ 00:00
<fs> mount /dev/sda1 /
<fs> sh "add-apt-repository ppa:scaleway/stable"
<fs> sh "apt -y install scaleway-ecosystem"
<fs> quit

You can use the sh command of guestfish or any other command to customize your image.

4 . Copy the QCOW2 file to the webserver directory

cp focal-server-cloudimg-amd64-disk-kvm.img /var/www/html

Creating a volume from the Cloud Image

1 . Start a new instance from the Cloud Image served by the builder instance. The following arguments are important:

  • root-volume=l:10G additional-volumes.0=l:10G - This will make sure that the resulting image size is 10G
  • tags.0=build_method=from-qcow2 - This will tell the bootscript to install from a provided QCOW2
  • tags.1=disk_img_url=http://<IP_adress_of_the_builder_instance>/focal-server-cloudimg-amd64-disk-kvm.img This specifies the URL of the Cloud Image to use
  • bootscript-id=c9ae8463-370d-4c83-8f71-b8282e7f6f81 - This specifies the image build bootscript (Note: The Bootscript ID is zone specific)

You should have a command like the following exemaple, run it using the Scaleway CLI:

 scw instance server create type=DEV1-S zone=fr-par-1 image=ubuntu_focal name=image-builder \
    root-volume=l:10G additional-volumes.0=l:10G \
    tags.0=build_method=from-qcow2 \
    tags.1=disk_img_url=http://51.15.201.97/focal-server-cloudimg-amd64-disk-kvm.img \
    bootscript-id=c9ae8463-370d-4c83-8f71-b8282e7f6f81

Note: The bootscript IDs for each zone are:
fr-par-1: c9ae8463-370d-4c83-8f71-b8282e7f6f81
fr-par-2: b12589d2-5a20-410a-a08e-5b4fbe577748
nl-ams-1: 914eabd4-90c2-432f-b54c-87dc373561b2
pl-waw-1: 57ce0deb-9cbc-498c-97d3-89837576f57f

2 . Connect yourself to the console of the building instance and watch for >>> Listening on port 22 to signal build done., which indicates that the building of the volume has completed.

scw instance server console <image_builder_instance_id>
...
Disk /dev/vda: 19531250 sectors, 9.3 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 00000000-0000-4000-A000-000000000001
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 19531216
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)
 
Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048            4095   1024.0 KiB  EF02  BIOS-BOOT
   2            4096          264191   127.0 MiB   EF00  EFI-SYSTEM
   3          264192         1050623   384.0 MiB   8300  boot
   4         1050624        19531216   8.8 GiB     8300 
>>> Listening on port 22 to signal build done.

Snapshotting the new Image

1 . Log yourself into the Scaleway Console and go to the Attached Volumes tab of your image builder instancer.

2 . Click the … button at the Volume0 to expand the menu.

3 . Click on Snapshot:

4 . Enter a meaningful name for the snapshot and click Take Snapshot.

5 . The snapshot displays in the list of your snapshots. Once it is ready (marked with a green dot), click … to expand the menu and click on Image from Snapshot:

6 . Enter a name for your image and select the x86_64 architecture. Confirm by clicking Create image from snapshot:

Your new image is ready now and you can start deploying your instances using this image.

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