Ubuntu Wiki

Adding new Ubuntu Core images/devices to the build process is very similar to that of Ubuntu Appliances.

• Make sure the new image/device has all the required snaps present in the snapstore. Some questions to answer:
  • Is it a completely new device with completely new gadget+kernel combination?
  • Is the kernel snap available for the device? Is it on the right track? (20/* for UC20, 18/* for UC18 etc)
  • Is the gadget snap available for the device? Same for the tracks.
  • What arches should it be provided for? Some devices support multiple architectures (armhf, arm64 etc.)
  • Does it need any other device-specific snaps preinstalled?

  • What should be the name of the new model? We usually follow the naming of: ubuntu-core-<SERIES>-<PLATFORM>[-<ARCH>][-<GRADE or STABILITY>], e.g. ubuntu-core-20-pi-arm64-dangerous.

• Create the new image model assertion JSON files, one per each supported arch. Please consult existing model JSON files for reference on how the fields should look like. There is a snapcore/models git repository with all the officially supported models so far.

  • When creating a model JSON file remember to bump the timestamp at the bottom to the current date
  • The publisher and brand should be 'canonical'

• Do a test build of the new model to make sure no error sneaked in. This can be done by substituting the brand-id and authority-id's from canonical to your private ones and signing the assertions locally, then using ubuntu-image snap as usual.

• Create an RT for IS to sign the model assertion with the canonical key, attaching the relevant .json files to the RT.
  • Example request - RT: 131731.

• Commit the new assertion and related JSON file to the snapcore/models github repository.

• Once the model assertion is signed, send the signed model files to snap-store-admins@lists.canonical.com for upload to the Snap Store.

• Add support for the new model in livecd-rootfs for the selected series (UC20 = focal, UC18 = bionic etc.).

  • livecd-rootfs translates the <ARCH>+<SUBARCH> cdimage pair into the model name.

  • This requires deciding on what SUBARCH should be used for the new image. When planning, keep in mind the possibility of us enabling the same platform for classic images.

  • The actual support for the translation to model name is in live-build/auto/config in livecd-rootfs. Look for a conditional switch for ubuntu-image IMAGEFORMAT.

• Prepare SRU for the livecd-rootfs changes, make sure it's verified and released into <SERIES>-updates

• To officially build the new image alongside all the other default Ubuntu Core images, add the new <ARCH>+<SUBARCH> pair to etc/default-arches in lp:ubuntu-cdimage (under the ubuntu-core project)

• Once there is a physical image built on cdimage, give the link to the new builds to the CertificationTeam (contact: Paul or Jonathan)