The k3s update script filters the assets of a
corresponding release for airgap images archives
and provides these as passthru attributes of the
k3s derivation. We use zstd archives, as these
offer the best compression ratios and decompression
speed. Furthermore, the `airgapImages` passthru
provides the images archive that matches the host
platform architecture, however, this only works
for aarch64 and x86_64. In addition, a txt file
listing all container images of a release is made
available via a passthru attribute. The airgap
images archives can be combined nicely with the
`services.k3s.images` option, e.g. to pre-provision
k3s nodes for environments without Internet
connectivity.
