Prefer running kubernetes version to configured one

app/models/machine_config.rb

@@ -42,11 +42,21 @@ def generate_config(output_type: server.talos_type)
     patch_worker_file = "#{Dir.tmpdir}/patch-worker-#{SecureRandom.hex}"
     File.write(patch_worker_file, replace_substitution_variables(config.patch_worker || ""))
 
+    # Prefer the running kubernetes version over the configured one since bootstrapping
+    # outdated versions can lead to issues.
+    running_or_configured_kubernetes_version =
+      # Avoid infinite recursion since talosconfig is used to determine the running kubernetes version
+      if output_type == "talosconfig"
+        config.kubernetes_version
+      else
+        server.cluster.running_kubernetes_version || config.kubernetes_version
+      end
+
     command = %(
       talosctl gen config \
         --install-disk #{install_disk} \
         --install-image #{config.install_image} \
-        --kubernetes-version #{config.kubernetes_version} \
+        --kubernetes-version #{running_or_configured_kubernetes_version} \
         --config-patch @#{patch_file} \
         --config-patch-control-plane @#{patch_control_plane_file} \
         --config-patch-worker @#{patch_worker_file} \

app/models/talosctl.rb

@@ -1,5 +1,7 @@
 require "open3"
 
+# Wrapper around the talosctl command line tool to interact with already bootstrapped Talos clusters
+
 class Talosctl
   def initialize(config_string)
     @config_string = config_string
@@ -35,6 +37,8 @@ def run(command)
     end
   end
 
+  private
+
   def config_file
     return @config_file if defined?(@config_file)
 

app/views/configs/_form.html.erb

@@ -48,7 +48,7 @@
   <%# installed via a disk image (which we do when bootstrapping). Can change it back to text_field %>
   <%# when/if Talos starts making proper use of the configuration. %>
   <%= f.hidden_field :install_image, readonly: true, hint: "Gets passed into the --imagedisk argument for talosctl gen config." %>
-  <%= f.text_field :kubernetes_version, placeholder: "1.26.3", hint: "Gets passed into the --kubernetes-version argument for talosctl gen config." %>
+  <%= f.text_field :kubernetes_version, placeholder: "1.30.6", hint: "Gets passed into the --kubernetes-version argument for talosctl gen config on new clusters. For already running clusters, the kubernetes version found on existing control planes will be used instead, to avoid accidentally onboarding nodes with incompatible Kubernetes versions." %>
 
   <%= f.label :kubespan, class: "mb-5 block" do %>
     <h3 class="font-bold mb-1 text-gray-900">Enable Kubespan</h3>