Update k0 to new-style nix modules

modules.bak/initca.nix

@@ -0,0 +1,42 @@
+{
+  pkgs ? import <nixpkgs> {},
+  ca ? null,
+  name ? "ca",
+  algo ? "rsa",
+  hosts ? [],
+  ...}:
+with pkgs;
+let
+  ca_csr = pkgs.writeText "${name}-csr.json" (builtins.toJSON {
+      inherit hosts;
+      CN = "${name}";
+      key = {
+        inherit algo;
+        size = if algo == "ecdsa" then 256 else 2048;
+      };
+      names = [
+        {
+          CN = "${name}";
+          O = "NixOS";
+          OU = "${name}.pki.caSpec";
+          L = "generated";
+        }
+      ];
+    }
+  );
+  ca' =
+      pkgs.runCommand "initca" {
+        buildInputs = [ pkgs.cfssl ];
+      } '' cfssl genkey -initca ${ca_csr} | cfssljson -bare ca;
+           mkdir -p $out; cp *.pem $out '';
+   initca = if ca != null then ca else ca';
+in
+  # make ca derivation sha depend on initca cfssl output
+  pkgs.stdenv.mkDerivation {
+    inherit name;
+    src = initca;
+    buildCommand = ''
+      mkdir -p $out;
+      cp -r $src/* $out
+    '';
+  }