fix: pin Helm 3.17.3 and helm-diff 3.12.5 for compatibility

kubernetes.core collection (v6.x) requires Helm 3.x (rejects 4.x).
helm-diff v3.13.0+ uses plugin.yaml fields (platformCommand,
platformHooks) that Helm 3.x cannot parse. Pin to last compatible
versions and ensure git is installed for helm plugin install.

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Aleksei Sviridkin <f@lex.la>

Author: lexfrei

README.md

@@ -182,7 +182,7 @@ Runs on `server[0]` only.
 | `cozystack_operator_variant` | `generic` | Operator variant: generic, talos, hosted |
 | `cozystack_api_server_port` | `6443` | API server port |
 | `cozystack_kubeconfig` | `/etc/rancher/k3s/k3s.yaml` | Kubeconfig path on target |
-| `cozystack_helm_version` | `4.1.1` | Helm binary version to install |
+| `cozystack_helm_version` | `3.17.3` | Helm binary version to install |
 | `cozystack_helm_binary` | `/usr/local/bin/helm` | Path to Helm binary on target |
 | `cozystack_create_platform_package` | `true` | Create Platform Package CR after install |
 | `cozystack_platform_variant` | `isp-full-generic` | Platform variant: default, isp-full, isp-hosted, isp-full-generic |

roles/cozystack/defaults/main.yml

@@ -28,11 +28,14 @@ cozystack_api_server_port: "6443"
 cozystack_kubeconfig: "/etc/rancher/k3s/k3s.yaml"
 
 # Helm binary version to install on the target node
-cozystack_helm_version: "4.1.1"
+cozystack_helm_version: "3.17.3"
 
 # Path to Helm binary on the target node
 cozystack_helm_binary: "/usr/local/bin/helm"
 
+# helm-diff plugin version (v3.13.0+ requires Helm 4 plugin.yaml format)
+cozystack_helm_diff_version: "3.12.5"
+
 # ---- Platform Package settings ----
 
 # Whether to create the Platform Package CR after chart install

roles/cozystack/tasks/main.yml

@@ -25,9 +25,16 @@
   become: true
   when: not ansible_check_mode
 
+- name: Ensure git is installed (required by helm plugin install)
+  ansible.builtin.package:
+    name: git
+    state: present
+  become: true
+
 - name: Install helm-diff plugin
   kubernetes.core.helm_plugin:
     plugin_path: https://github.com/databus23/helm-diff
+    plugin_version: "{{ cozystack_helm_diff_version }}"
     state: present
     binary_path: "{{ cozystack_helm_binary }}"
   become: true