cmd/k8s-operator/deploy/manifests: check if IPv6 module is loaded before using it

Before attempting to enable IPv6 forwarding in the proxy init container
check if the relevant module is found, else the container crashes
on hosts that don't have it.

Updates#11860

Signed-off-by: Irbe Krumina <irbe@tailscale.com>

cmd/k8s-operator/deploy/manifests/proxy.yaml

@@ -14,10 +14,8 @@ spec:
         - name: sysctler
           securityContext:
             privileged: true
-          command: ["/bin/sh"]
-          args:
-            - -c
-            - sysctl -w net.ipv4.ip_forward=1 net.ipv6.conf.all.forwarding=1
+          command: ["/bin/sh", "-c"]
+          args: [sysctl -w net.ipv4.ip_forward=1; if sysctl net.ipv6.conf.all.forwarding; then sysctl -w net.ipv6.conf.all.forwarding=1; fi]
       resources:
         requests:
           cpu: 1m

cmd/k8s-operator/testutils_test.go

@@ -184,8 +184,8 @@ func expectedSTS(t *testing.T, cl client.Client, opts configOpts) *appsv1.Statef
 						{
 							Name:    "sysctler",
 							Image:   "tailscale/tailscale",
-							Command: []string{"/bin/sh"},
-							Args:    []string{"-c", "sysctl -w net.ipv4.ip_forward=1 net.ipv6.conf.all.forwarding=1"},
+							Command: []string{"/bin/sh", "-c"},
+							Args:    []string{"sysctl -w net.ipv4.ip_forward=1; if sysctl net.ipv6.conf.all.forwarding; then sysctl -w net.ipv6.conf.all.forwarding=1; fi"},
 							SecurityContext: &corev1.SecurityContext{
 								Privileged: ptr.To(true),
 							},