Implement HA control plane with Load Balancer (3-3 topology)

Major changes:
- Terraform: Scale to 3 control planes (cx23) + 3 workers (cx33)
- Terraform: Add Hetzner Load Balancer (lb11) for Kubernetes API
- Terraform: Add kube_api_lb_ip output
- Ansible: Add community.network collection to requirements
- Ansible: Update inventory to include LB endpoint
- Ansible: Configure secondary CPs and workers to join via LB
- Ansible: Add k3s_join_endpoint variable for HA joins
- Workflow: Add imports for cp-2, cp-3, and worker-3
- Docs: Update STABLE_BASELINE.md with HA topology and phase gates

Topology:
- 3 control planes (cx23 - 2 vCPU, 8GB RAM each)
- 3 workers (cx33 - 4 vCPU, 16GB RAM each)
- 1 Load Balancer (lb11) routing to all 3 control planes on port 6443
- Workers and secondary CPs join via LB endpoint for HA

Cost impact: +~€26/month (2 extra CPs + 1 extra worker + LB)

ansible/generate_inventory.py

@@ -32,6 +32,7 @@ def main():
     worker_names = outputs["worker_names"]["value"]
     worker_ips = outputs["worker_ips"]["value"]
     worker_private_ips = outputs["worker_private_ips"]["value"]
+    kube_api_lb_ip = outputs.get("kube_api_lb_ip", {}).get("value", control_plane_ips[0])
 
     control_planes = [
         {
@@ -59,6 +60,7 @@ def main():
         "control_planes": control_planes,
         "workers": workers,
         "private_key_file": outputs["ssh_private_key_path"]["value"],
+        "kube_api_lb_ip": kube_api_lb_ip,
     }
 
     env = Environment(loader=FileSystemLoader("."))

ansible/inventory.tmpl

@@ -17,3 +17,4 @@ ansible_user=root
 ansible_python_interpreter=/usr/bin/python3
 ansible_ssh_private_key_file={{ private_key_file }}
 k3s_version=latest
+kube_api_endpoint={{ kube_api_lb_ip }}

ansible/requirements.yml

@@ -3,3 +3,5 @@ collections:
     version: ">=2.4.0"
   - name: community.general
     version: ">=8.0.0"
+  - name: community.network
+    version: ">=5.0.0"

ansible/roles/k3s-server/tasks/main.yml

@@ -15,9 +15,9 @@
   set_fact:
     k3s_install_needed: "{{ (not k3s_service.stat.exists) or ((k3s_service_state.stdout | default('')) != 'active') }}"
 
-- name: Wait for primary API on 6443 (secondary only)
+- name: Wait for API endpoint on 6443 (secondary only)
   wait_for:
-    host: "{{ k3s_primary_ip }}"
+    host: "{{ k3s_join_endpoint | default(k3s_primary_ip) }}"
     port: 6443
     state: started
     timeout: 120
@@ -81,7 +81,7 @@
         K3S_TOKEN: "{{ k3s_token }}"
       command: >-
         /tmp/install-k3s.sh server
-        --server https://{{ k3s_primary_ip }}:6443
+        --server https://{{ k3s_join_endpoint | default(k3s_primary_ip) }}:6443
         --advertise-address={{ k3s_node_ip }}
         --node-ip={{ k3s_node_ip }}
         {% if k3s_disable_embedded_ccm | bool %}--disable-cloud-controller{% endif %}

ansible/site.yml

@@ -73,6 +73,8 @@
     k3s_primary_ip: "{{ hostvars[groups['control_plane'][0]]['k3s_primary_private_ip'] }}"
     k3s_primary_public_ip: "{{ hostvars[groups['control_plane'][0]]['k3s_primary_public_ip'] }}"
     k3s_node_ip: "{{ k3s_private_ip }}"
+    # Use Load Balancer for HA - all control planes join via LB endpoint
+    k3s_join_endpoint: "{{ kube_api_endpoint | default(hostvars[groups['control_plane'][0]]['k3s_primary_private_ip']) }}"
 
   roles:
     - k3s-server
@@ -83,7 +85,8 @@
 
   vars:
     k3s_token: "{{ hostvars[groups['control_plane'][0]]['k3s_token'] }}"
-    k3s_server_url: "https://{{ hostvars[groups['control_plane'][0]]['k3s_primary_private_ip'] }}:6443"
+    # Use Load Balancer for HA - workers join via LB endpoint
+    k3s_server_url: "https://{{ kube_api_endpoint | default(hostvars[groups['control_plane'][0]]['k3s_primary_private_ip']) }}:6443"
     k3s_node_ip: "{{ k3s_private_ip }}"
 
   roles: