Move over stuff from nixos-servers

scripts/default.nix

@@ -0,0 +1,23 @@
+{ nixpkgs, flutils, ... }: flutils.lib.eachDefaultSystem (system:
+let
+  pkgs = nixpkgs.legacyPackages.${system};
+  createScript = { name, runtimeInputs, scriptPath, extraWrapperFlags ? "", ... }:
+    let
+      script = (pkgs.writeScriptBin name (builtins.readFile scriptPath)).overrideAttrs (old: {
+        buildCommand = "${old.buildCommand}\n patchShebangs $out";
+      });
+    in
+    pkgs.symlinkJoin {
+      inherit name;
+      paths = [ script ] ++ runtimeInputs;
+      buildInputs = [ pkgs.makeWrapper ];
+      postBuild = "wrapProgram $out/bin/${name} --set PATH $out/bin ${extraWrapperFlags}";
+    };
+in
+{
+  packages.gen-k3s-cert = createScript {
+    name = "create-k3s-cert";
+    runtimeInputs = with pkgs; [ openssl coreutils openssh yq ];
+    scriptPath = ./gen-k3s-cert.sh;
+  };
+})

scripts/gen-k3s-cert.sh

@@ -0,0 +1,88 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+IFS=$'\n\t'
+
+username="${1-}"
+host="${2-}"
+output_path="${3:-.}"
+
+if [ -z "$username" ] || [ -z "$host" ]
+  then
+    echo "Usage: $0 USERNAME HOST [OUTPUTPATH]"
+    exit 1
+fi
+
+# Create a temporary directory
+temp=$(mktemp -d)
+
+# Function to cleanup temporary directory on exit
+cleanup() {
+  rm -rf "$temp"
+}
+trap cleanup EXIT
+
+echo Generating the private key
+openssl genpkey -algorithm ed25519 -out "$temp/key.pem"
+
+echo Generating the certificate request
+openssl req -new -key "$temp/key.pem" -out "$temp/req.csr" -subj "/CN=$username"
+
+echo Creating K8S CSR manifest
+csr="$(cat "$temp/req.csr" | base64 | tr -d '\n')"
+k8s_csr="apiVersion: certificates.k8s.io/v1
+kind: CertificateSigningRequest
+metadata:
+  name: $username-csr
+spec:
+  request: $csr
+  expirationSeconds: 307584000 # 10 years
+  signerName: kubernetes.io/kube-apiserver-client
+  usages:
+    - digital signature
+    - key encipherment
+    - client auth
+"
+
+echo Creating K8S CSR resource
+ssh "root@$host" "echo \"$k8s_csr\" | k3s kubectl apply -f -"
+
+echo Approving K8S CSR
+ssh "root@$host" "k3s kubectl certificate approve $username-csr"
+
+echo Retrieving approved certificate
+encoded_cert="$(ssh root@"$host" "k3s kubectl get csr $username-csr -o jsonpath='{.status.certificate}'")"
+
+echo Retrieving default K3S kubeconfig
+base_kubeconfig="$(ssh root@"$host" "cat /etc/rancher/k3s/k3s.yaml")"
+
+echo Getting certificate authority data from default kubeconfig
+cert_authority_data="$(echo -n "$base_kubeconfig" | yq -r '.clusters[0].cluster."certificate-authority-data"')"
+
+echo Generating final kubeconfig
+result_kubeconfig="apiVersion: v1
+clusters:
+- cluster:
+    certificate-authority-data: $cert_authority_data
+    server: https://$host:6443
+  name: default
+contexts:
+- context:
+    cluster: default
+    user: $username
+  name: default
+current-context: default
+kind: Config
+preferences: {}
+users:
+- name: $username
+  user:
+    client-certificate: $username.crt
+    client-key: $username.key
+"
+
+echo Writing resulting files to "$output_path"
+echo -n "$encoded_cert" | base64 -d > $output_path/$username.crt
+echo -n "$result_kubeconfig" > $output_path/config
+cp $temp/key.pem $output_path/$username.key
+