Enhance ironcore-image with Platform-Specific Layer Support and CPU Architecture Variants

[afritzler]

Description

The ironcore-image project, responsible for defining the OCI manifest for our Operating System images, currently includes layers like rootfs, initramfs, and kernel. We need to improve this project by introducing platform-specific support, where each platform type holds a distinct subset of these layers. Additionally, the project should be capable of handling different CPU architectures, specifically arm64 and amd64.

Requirements

1. Platform Support:

   • virtualization platform should include only the rootfs layer.
   • baremetal platform should encompass kernel, initramfs, and rootfs layers.

2. CPU Architecture Support:

   • Ensure compatibility with arm64 and amd64 architectures.

Expected Outcome

• Enhanced flexibility in the ironcore-image project to generate OCI manifests tailored to specific platform requirements.
• Robust support for the primary CPU architectures in use, enhancing our OS image's compatibility and reach.

Additional Context

• This enhancement is crucial for optimizing our OS images for different deployment scenarios, like virtualized environments versus bare-metal setups.
• Consideration for the varying requirements of arm64 and amd64 architectures is essential for broadening our OS's applicability.

Sample Manifest

An ironcore-image OCI Specification Draft could look like the following:

schemaVersion: 2.0
mediaType: application/vnd.oci.image.manifest.v1+json

# Manifests for different platforms and architectures
manifests:
  - # Virtualization platform - rootfs only
    mediaType: application/vnd.oci.image.manifest.v1+json
    platform:
      architecture: amd64
      os: linux
      variant: virtualization
    layers:
      - mediaType: application/vnd.oci.image.layer.v1.tar+gzip
        digest: "<digest-rootfs-amd64>"
        size: <size>
        annotations:
          title: "rootfs"

  - # Virtualization platform - rootfs only (ARM64)
    mediaType: application/vnd.oci.image.manifest.v1+json
    platform:
      architecture: arm64
      os: linux
      variant: virtualization
    layers:
      - mediaType: application/vnd.oci.image.layer.v1.tar+gzip
        digest: "<digest-rootfs-arm64>"
        size: <size>
        annotations:
          title: "rootfs"

  - # Baremetal platform - kernel, initramfs, rootfs (AMD64)
    mediaType: application/vnd.oci.image.manifest.v1+json
    platform:
      architecture: amd64
      os: linux
      variant: baremetal
    layers:
      - mediaType: application/vnd.oci.image.layer.v1.tar+gzip
        digest: "<digest-kernel-amd64>"
        size: <size>
        annotations:
          title: "kernel"
      - mediaType: application/vnd.oci.image.layer.v1.tar+gzip
        digest: "<digest-initramfs-amd64>"
        size: <size>
        annotations:
          title: "initramfs"
      - mediaType: application/vnd.oci.image.layer.v1.tar+gzip
        digest: "<digest-rootfs-amd64>"
        size: <size>
        annotations:
          title: "rootfs"

  - # Baremetal platform - kernel, initramfs, rootfs (ARM64)
    mediaType: application/vnd.oci.image.manifest.v1+json
    platform:
      architecture: arm64
      os: linux
      variant: baremetal
    layers:
      - mediaType: application/vnd.oci.image.layer.v1.tar+gzip
        digest: "<digest-kernel-arm64>"
        size: <size>
        annotations:
          title: "kernel"
      - mediaType: application/vnd.oci.image.layer.v1.tar+gzip
        digest: "<digest-initramfs-arm64>"
        size: <size>
        annotations:
          title: "initramfs"
      - mediaType: application/vnd.oci.image.layer.v1.tar+gzip
        digest: "<digest-rootfs-arm64>"
        size: <size>
        annotations:
          title: "rootfs"
# Replace <digest-*> and <size> with actual hash values and sizes of the layers.