nixos/kubernetes: adds argument to mkCert defaulting to kubernetes group

[PedroRegisPOAR]

Description of changes

This PR adds an argument to the mkCert function. It allows to use mkCert passing as argument the group name. Previously it had the group hardcoded as nogroup.

With this PR it makes the new default to be the kubernetes group.

For reference, if this contribution is accepted the following issue should be updated: #55370

Things done

Tested it with:

nix \
build \
--no-link \
--print-out-paths \
--override-flake \
nixpkgs \
'github:PedroRegisPOAR/nixpkgs/a5deaf9e935f716ed3200c37abc656108c21cfad' \
'nixpkgs#nixosTests.kubernetes.dns-single-node' \
'nixpkgs#nixosTests.kubernetes.dns-multi-node' \
'nixpkgs#nixosTests.kubernetes.rbac-single-node' \
'nixpkgs#nixosTests.kubernetes.rbac-multi-node'

Outputs:

/nix/store/rpxkyqwnwhvqsxvm2aznvdz95y5cgy5k-vm-test-run-kubernetes-dns-multinode
/nix/store/mb9ca1i70xaw52ljc03jqdpb1853m9rw-vm-test-run-kubernetes-dns-singlenode
/nix/store/ndfmpfbbkigqywni4jriv9f62ylka846-vm-test-run-kubernetes-rbac-multinode
/nix/store/8hsa36b5ig42l3ga9hskmlx8sxv5grhq-vm-test-run-kubernetes-rbac-singlenode

For local testing:

nix \
build \
--no-link \
--print-out-paths \
'.#nixosTests.kubernetes.dns-single-node' \
'.#nixosTests.kubernetes.dns-multi-node' \
'.#nixosTests.kubernetes.rbac-single-node' \
'.#nixosTests.kubernetes.rbac-multi-node'

Description of changes

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[PedroRegisPOAR]

Friendly ping: @johanot @offlinehacker @saschagrunert @srhb

[PedroRegisPOAR]

@ofborg test kubernetes.dns-single-node kubernetes.dns-multi-node kubernetes.rbac-single-node kubernetes.rbac-multi-node