amazon-image.nix: Resolve failure to include resize2fs

[talyz]

Motivation for this change

Since 34234dc, for resize2fs to be automatically included in
initrd, a filesystem needed for boot must be explicitly defined as an
ext* type filesystem.

Things done

Tested by building the amazon image with

nix-build -I nixpkgs="/nixpkgs" -o amazon-image /nixpkgs/nixos -A config.system.build.amazonImage --arg configuration "{ imports = [ <nixpkgs/nixos/maintainers/scripts/ec2/amazon-image.nix> ]; ec2.hvm = true; }"

and both running it in qemu and on ec2.

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.

---

[infinisil]

And the filesystem is ext4 always anyways?

[talyz]

Yes, although not immediately obvious, the amazon images will always use ext4, since that is the default value of the "fsType" argument to make-disk-image.nix. It should probably be passed explicitly instead, though. I'll add that as well.

[talyz]

fsType = config.fileSystems."/".fsType; would also work, but only ext4 is supported by make-disk-image.nix when partitionTableType is "legacy"...

[infinisil]

Looking good, thanks!