feat(k3s-server): add kube_vip_enabled and metal_lb_enabled switches

- gate the control-plane VIP and kube-vip service LB on kube_vip_enabled
- gate the MetalLB manifest and pool on metal_lb_enabled
- add argument_specs entries in both roles
- document both switches in sample inventory and README
- update metal_lb deploy-condition test and add a kube-vip deploy-condition test

.github/scripts/test-kube-vip-deploy-condition.py

@@ -0,0 +1,166 @@
+#!/usr/bin/env python3
+"""Regression test for the kube-vip deploy conditions.
+
+The control-plane VIP (roles/k3s_server/tasks/vip.yml) and the kube-vip
+service load balancer (roles/k3s_server/tasks/kube-vip.yml) are both included
+from roles/k3s_server/tasks/main.yml. Before this switch existed the VIP
+include had no gate and always ran, so a user who wanted no kube-vip (single
+node or external LB) could not opt out.
+
+This test loads the real `when` expressions from the k3s_server task file and
+evaluates them against representative variable sets, asserting that:
+
+- the control-plane VIP is deployed only when kube_vip_enabled is true;
+- the service load balancer is deployed only when kube_vip_enabled is true
+  AND kube_vip_lb_ip_range is defined.
+"""
+
+from __future__ import print_function
+
+import os
+import re
+import subprocess
+
+import yaml
+from jinja2 import Environment
+
+VIP_WHEN = "kube_vip_enabled"
+KUBE_VIP_WHEN = "kube_vip_enabled and kube_vip_lb_ip_range is defined"
+
+
+def repo_root():
+    return subprocess.check_output(
+        ["git", "rev-parse", "--show-toplevel"], text=True
+    ).strip()
+
+
+def fail(message):
+    raise SystemExit("kube-vip deploy condition test failed: " + message)
+
+
+def extract_when(path, task_name):
+    """Return the `when:` expression string for the named task."""
+    with open(path, encoding="utf-8") as handle:
+        doc = yaml.safe_load(handle)
+    for task in doc:
+        if task.get("name") == task_name:
+            when = task.get("when")
+            return (when or "").strip()
+    return None
+
+
+def evaluate(when, variables):
+    """Evaluate a `when` expression against variables using Jinja2."""
+    env = Environment()
+
+    def fake_bool(value):
+        # Minimal stand-in for Ansible's truthiness filter used by `| bool`.
+        if isinstance(value, bool):
+            return value
+        if value is None:
+            return False
+        return str(value).lower() in ("1", "true", "yes", "on")
+
+    env.filters["bool"] = fake_bool
+    template = env.from_string("{{ " + when + " }}")
+    rendered = template.render(**variables)
+    # The expression renders to the literal strings "True"/"False".
+    if rendered == "True":
+        return True
+    if rendered == "False":
+        return False
+    fail("condition did not render to a boolean: {0!r}".format(rendered))
+
+
+def assert_deployment(when, variables, expected, label):
+    result = evaluate(when, variables)
+    verdict = "deploy" if result else "skip"
+    expected_verdict = "deploy" if expected else "skip"
+    if result != expected:
+        fail(
+            "{0}: expected to {1} but the condition chose to {2} "
+            "(vars: {3})".format(label, expected_verdict, verdict, variables)
+        )
+
+
+def scenarios():
+    """Yield (variables, expected_vip, expected_service_lb, label) pairs."""
+    yield (
+        # Default inventory: kube-vip enabled, no service LB range.
+        {
+            "kube_vip_enabled": True,
+        },
+        True,
+        False,
+        "default: kube-vip VIP only",
+    )
+    yield (
+        # kube-vip owns the service LB range too.
+        {
+            "kube_vip_enabled": True,
+            "kube_vip_lb_ip_range": "192.168.30.80-192.168.30.90",
+        },
+        True,
+        True,
+        "kube-vip VIP and service LB",
+    )
+    yield (
+        # Explicitly disabled, no LB range.
+        {
+            "kube_vip_enabled": False,
+        },
+        False,
+        False,
+        "kube_vip_enabled: false",
+    )
+    yield (
+        # Explicitly disabled even when the LB range is present.
+        {
+            "kube_vip_enabled": False,
+            "kube_vip_lb_ip_range": "192.168.30.80-192.168.30.90",
+        },
+        False,
+        False,
+        "kube_vip_enabled: false despite LB range",
+    )
+
+
+def main():
+    root = repo_root()
+    server_tasks = os.path.join(root, "roles", "k3s_server", "tasks", "main.yml")
+
+    vip_when = extract_when(server_tasks, "Deploy vip manifest")
+    kube_vip_when = extract_when(server_tasks, "Deploy kube-vip manifest")
+
+    if vip_when is None:
+        fail("could not find 'Deploy vip manifest' when condition")
+    if kube_vip_when is None:
+        fail("could not find 'Deploy kube-vip manifest' when condition")
+
+    if vip_when != VIP_WHEN:
+        fail(
+            "k3s_server/tasks/main.yml 'Deploy vip manifest' when condition "
+            "changed unexpectedly:\n"
+            "  expected: {0}\n  got:      {1}".format(VIP_WHEN, vip_when)
+        )
+    if kube_vip_when != KUBE_VIP_WHEN:
+        fail(
+            "k3s_server/tasks/main.yml 'Deploy kube-vip manifest' when "
+            "condition changed unexpectedly:\n"
+            "  expected: {0}\n  got:      {1}".format(KUBE_VIP_WHEN, kube_vip_when)
+        )
+
+    for variables, expected_vip, expected_service_lb, label in scenarios():
+        assert_deployment(vip_when, variables, expected_vip, "vip " + label)
+        assert_deployment(
+            kube_vip_when,
+            variables,
+            expected_service_lb,
+            "service_lb " + label,
+        )
+
+    print("kube-vip deploy condition regression test passed for all scenarios")
+
+
+if __name__ == "__main__":
+    main()

.github/scripts/test-metallb-deploy-condition.py

@@ -10,7 +10,8 @@ scenario.
 
 This test loads the real `when` expressions from both task files and evaluates
 them against representative variable sets, asserting MetalLB is deployed in
-every topology except when kube-vip owns the VIP range or Cilium BGP is enabled.
+every topology except when MetalLB is explicitly disabled, kube-vip owns the
+VIP range, or Cilium BGP is enabled.
 """
 
 from __future__ import print_function
@@ -23,6 +24,7 @@ import yaml
 from jinja2 import Environment
 
 METALLB_WHEN = (
+    "metal_lb_enabled and "
     "kube_vip_lb_ip_range is not defined and "
     "not (cilium_bgp | default(false) | bool)"
 )
@@ -88,6 +90,7 @@ def scenarios():
     yield (
         # Default Flannel inventory (all.yml sets cilium_bgp: false).
         {
+            "metal_lb_enabled": True,
             "cilium_bgp": False,
             "cilium_iface": None,
         },
@@ -98,6 +101,7 @@ def scenarios():
         # Calico CNI with no Cilium variable in scope (issue #644): cilium_bgp
         # is genuinely undefined, so `default(false)` must keep MetalLB on.
         {
+            "metal_lb_enabled": True,
             "calico_iface": "eth1",
         },
         True,
@@ -106,6 +110,7 @@ def scenarios():
     yield (
         # Cilium CNI with BGP disabled: MetalLB must still be deployed.
         {
+            "metal_lb_enabled": True,
             "cilium_bgp": False,
             "cilium_iface": "eth1",
         },
@@ -115,6 +120,7 @@ def scenarios():
     yield (
         # Cilium CNI with BGP enabled: Cilium provides the LB, skip MetalLB.
         {
+            "metal_lb_enabled": True,
             "cilium_bgp": True,
             "cilium_iface": "eth1",
         },
@@ -124,12 +130,21 @@ def scenarios():
     yield (
         # kube-vip is the load balancer provider: skip MetalLB.
         {
+            "metal_lb_enabled": True,
             "kube_vip_lb_ip_range": "192.168.30.80-192.168.30.90",
             "cilium_bgp": False,
         },
         False,
         "kube-vip owns the VIP range",
     )
+    yield (
+        # MetalLB explicitly disabled (external LB / single node): skip.
+        {
+            "metal_lb_enabled": False,
+        },
+        False,
+        "metal_lb_enabled: false (external LB)",
+    )
 
 
 def main():