Snapcraft unable to compile ARM64 kernel

[RuhanSA079]

Bug Description

I am trying to cross-compile a kernel for a ARM64 device, and it seems on both 7.x/stable and 8.x/stable channels that the snapcraft application fails to download the snapd:arm64 package, with the error: E: Can't select candidate version from package snapd:arm64 as it has no candidate
Failed to build 'kernel'.

This build-process happens on a Ubuntu Focal Multipass instance running on a AMD64 machine.
Snapcraft versions: 7.x/stable (7.5.8) and 8.x/stable (8.5.1)

This has worked last time I tried to compile a kernel, a few months back.

To Reproduce

Not sure how to replicate, try to cross-compile a kernel?
Multipass instance compile options: (Manual compile commands)
snapcraft --target-arch=arm64 --destructive-mode --enable-experimental-target-arch --enable-experimental-plugins

Environment

Running Multipass snap, version 1.15.0 on Ubuntu Bionic machine
Mutipass container version: Ubuntu 20.04.6 LTS

snapcraft.yaml

name: my-kernel
version: "20-8"
adopt-info: kernel
summary: Generic Linux kernel description: |
  Kernel for testing

grade: stable
confinement: strict
type: kernel

architectures:
  - build-on: amd64
    run-on: arm64
build-base: core20

parts:
  kernel:
    plugin: kernel
    source: github-link-removed
    source-type: git
    source-branch: lf-5.10.y
    source-depth: 1
    kernel-kdefconfig: [imx8_var_defconfig, snappy/generic.config, snappy/security.config, snappy/systemd.config, snappy/snappy.config, snappy/containers.config ]
    kernel-kconfigs:
      - CONFIG_LOCALVERSION="-v0.8"
      - CONFIG_SYSFS=y
      - CONFIG_GPIO_SYSFS=y
      - CONFIG_GPIO_GENERIC=y
      - CONFIG_HW_RANDOM_TPM=m
      - CONFIG_TCG_TPM=m
      - CONFIG_TCG_TIS_CORE=m
      - CONFIG_TCG_TIS_SPI=m
      - CONFIG_SECURITYFS=y
      - CONFIG_LSM="yama,integrity,apparmor"
      - CONFIG_SECURITY_APPARMOR=y
      - CONFIG_AUDIT=y
      - CONFIG_SECURITY_APPARMOR_BOOTPARAM_VALUE=1
      - CONFIG_DEFAULT_SECURITY_APPARMOR=y
      - CONFIG_SYN_COOKIES=y
      - CONFIG_STRICT_DEVMEM=y
      - CONFIG_DEBUG_RODATA=y
      - CONFIG_CC_STACKPROTECTOR=y
      - CONFIG_CC_STACKPROTECTOR_STRONG=y
      - CONFIG_DEBUG_SET_MODULE_RONX=n
      - CONFIG_ENCRYPTED_KEYS=y
      - CONFIG_SQUASHFS_XATTR=y
      - CONFIG_SQUASHFS_XZ=y
      - CONFIG_DEVPTS_MULTIPLE_INSTANCES=y
      - CONFIG_TMPFS_XATTR=y
      - CONFIG_TMPFS_POSIX_ACL=y
    override-pull: |
      snapcraftctl pull
      set -e
      echo "Applying Ubuntu Core AppArmor patches to the kernel..."
      git apply -v ../../../patches/apparmor-patch-510.patch
      git apply -v ../../../patches/configs-patch-510.patch
      snapcraftctl set-version "20-8"
    kernel-initrd-compression: lz4
    kernel-initrd-firmware:
      - firmware/imx/sdma/sdma-imx7d.bin

    kernel-device-trees: [ freescale/imx8mp-device-tree-for-kernel ]
    kernel-image-target: Image
    kernel-with-firmware: false
    kernel-add-ppa: true
    kernel-initrd-stage-firmware: true
    organize:
      kernel.img: Image
    after: [ firmware ]
    build-packages:
      - cpio
      - libc6-dev
      - bison
      - flex
      - lzop
      - libssl-dev
      - on amd64 to arm64:
        - gcc-aarch64-linux-gnu:amd64

  #TODO Strip most firmwares out to make kernel smaller.
  firmware:
    plugin: nil
    source: linux-firmware
    override-build: |
      mkdir -p $SNAPCRAFT_PART_INSTALL/firmware
      cp -av ../../../linux-firmware/* $SNAPCRAFT_PART_INSTALL/firmware/

build-packages:
    - zstd
    - bison
    - device-tree-compiler
    - dpkg-dev
    - flex
    - initramfs-tools-core
    - libfdt-dev
    - libssl-dev
    - lzop
    - python3-crypto
    - python3-pycryptodome
    - python3-pyelftools
    - python3-serial
    - u-boot-tools
    - wget
    - libjson-c-dev
    - binutils-${SNAPCRAFT_ARCH_TRIPLET}
    - gcc-${SNAPCRAFT_ARCH_TRIPLET}

Relevant log output

+ '[' -d /home/ubuntu/kernel/parts/kernel/src/kernel ']'
+ KERNEL_SRC=/home/ubuntu/kernel/parts/kernel/src
+ echo PATH=/snap/snapcraft/13058/libexec/snapcraft:/snap/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PATH=/snap/snapcraft/13058/libexec/snapcraft:/snap/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+ echo KERNEL_SRC=/home/ubuntu/kernel/parts/kernel/src
KERNEL_SRC=/home/ubuntu/kernel/parts/kernel/src
+ initrd_installed_kernel_modules=
+ initrd_configured_kernel_modules=
+ echo 'Getting ubuntu-core-initrd....'
Getting ubuntu-core-initrd....
+ '[' '!' -e /home/ubuntu/kernel/parts/kernel/build/ubuntu-core-initramfs ']'
+ download_core_initrd arm64 /home/ubuntu/kernel/parts/kernel/build/ubuntu-core-initramfs
+ apt-get download ubuntu-core-initramfs:arm64
Get:1 http://ppa.launchpad.net/snappy-dev/image/ubuntu focal/main arm64 ubuntu-core-initramfs arm64 51.15 [18.2 MB]
Fetched 18.2 MB in 48s (381 kB/s)
W: Download is performed unsandboxed as root as file '/home/ubuntu/kernel/parts/kernel/build/ubuntu-core-initramfs_51.15_arm64.deb' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied)
+ dpkg -x ubuntu-core-initramfs_51.15_arm64.deb /home/ubuntu/kernel/parts/kernel/build/ubuntu-core-initramfs
+ echo 'Getting snapd deb for snap bootstrap...'
Getting snapd deb for snap bootstrap...
+ '[' '!' -e /home/ubuntu/kernel/parts/kernel/build/ubuntu-core-initramfs/usr/lib/snapd ']'
+ download_snap_bootstrap arm64 /home/ubuntu/kernel/parts/kernel/build/ubuntu-core-initramfs
+ apt-get download snapd:arm64
E: Can't select candidate version from package snapd:arm64 as it has no candidate
Failed to build 'kernel'.

Recommended resolution:
Check the build logs and ensure the part's configuration and sources are correct.

Additional context

No response

[RuhanSA079]

It appears to be an aptitude repository problem, where it does not allow you to download the snapd deb file, seperately.
Reproduce with: apt-get download snapd or apt-get download snapd:arm64, and it will return an error -> E: Can't select candidate version from package snapd:<arch> as it has no candidate

I could reproduce this on my Ubuntu 20 and Ubuntu 22 Multipass instances.