From a81a846c11821dce063aac980bb9d6352447edfb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan-Otto=20Kr=C3=B6pke?= <joe@cloudeteer.de>
Date: Thu, 6 Jun 2024 18:12:45 +0200
Subject: [PATCH] `azurerm_kubernetes_cluster`: Support for upgrade path from
 Azure CNI to Azure CNI Overlay

---
 .../containers/kubernetes_cluster_resource.go | 23 +++++++++++++++++--
 .../docs/r/kubernetes_cluster.html.markdown   |  4 ++--
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/internal/services/containers/kubernetes_cluster_resource.go b/internal/services/containers/kubernetes_cluster_resource.go
index 847d6c2ab4e0..6ba9e2c5ac9a 100644
--- a/internal/services/containers/kubernetes_cluster_resource.go
+++ b/internal/services/containers/kubernetes_cluster_resource.go
@@ -114,6 +114,12 @@ func resourceKubernetesCluster() *pluginsdk.Resource {
 			pluginsdk.ForceNewIfChange("network_profile.0.network_policy", func(ctx context.Context, old, new, meta interface{}) bool {
 				return old.(string) != "" || new.(string) != string(managedclusters.NetworkPolicyCilium)
 			}),
+			pluginsdk.ForceNewIfChange("network_profile.0.pod_cidr", func(ctx context.Context, old, new, meta interface{}) bool {
+				return old.(string) != ""
+			}),
+			pluginsdk.ForceNewIfChange("network_profile.0.pod_cidrs", func(ctx context.Context, old, new, meta interface{}) bool {
+				return len(old.([]interface{})) > 0
+			}),
 			pluginsdk.ForceNewIfChange("custom_ca_trust_certificates_base64", func(ctx context.Context, old, new, meta interface{}) bool {
 				return len(old.([]interface{})) > 0 && len(new.([]interface{})) == 0
 			}),
@@ -1031,7 +1037,6 @@ func resourceKubernetesCluster() *pluginsdk.Resource {
 							Type:         pluginsdk.TypeString,
 							Optional:     true,
 							Computed:     true,
-							ForceNew:     true,
 							ValidateFunc: validate.CIDR,
 						},
 
@@ -1039,7 +1044,6 @@ func resourceKubernetesCluster() *pluginsdk.Resource {
 							Type:     pluginsdk.TypeList,
 							Optional: true,
 							Computed: true,
-							ForceNew: true,
 							Elem: &pluginsdk.Schema{
 								Type:         pluginsdk.TypeString,
 								ValidateFunc: validation.StringIsNotEmpty,
@@ -2340,6 +2344,21 @@ func resourceKubernetesClusterUpdate(d *pluginsdk.ResourceData, meta interface{}
 			existing.Model.Properties.NetworkProfile.NetworkDataplane = pointer.To(managedclusters.NetworkDataplane(ebpfDataPlane))
 		}
 
+		if key := "network_profile.0.network_plugin_mode"; d.HasChange(key) {
+			networkPluginMode := d.Get(key).(string)
+			existing.Model.Properties.NetworkProfile.NetworkPluginMode = pointer.To(managedclusters.NetworkPluginMode(networkPluginMode))
+		}
+
+		if key := "network_profile.0.pod_cidr"; d.HasChange(key) {
+			podCidr := d.Get(key).(string)
+			existing.Model.Properties.NetworkProfile.PodCidr = pointer.To(podCidr)
+		}
+
+		if key := "network_profile.0.pod_cidrs"; d.HasChange(key) {
+			podCidrs := d.Get(key).([]interface{})
+			existing.Model.Properties.NetworkProfile.PodCidrs = utils.ExpandStringSlice(podCidrs)
+		}
+
 		if key := "network_profile.0.outbound_type"; d.HasChange(key) {
 			outboundType := managedclusters.OutboundType(d.Get(key).(string))
 			existing.Model.Properties.NetworkProfile.OutboundType = pointer.To(outboundType)
diff --git a/website/docs/r/kubernetes_cluster.html.markdown b/website/docs/r/kubernetes_cluster.html.markdown
index d61a413f6234..70916e38934d 100644
--- a/website/docs/r/kubernetes_cluster.html.markdown
+++ b/website/docs/r/kubernetes_cluster.html.markdown
@@ -699,9 +699,9 @@ A `network_profile` block supports the following:
 
 * `outbound_type` - (Optional) The outbound (egress) routing method which should be used for this Kubernetes Cluster. Possible values are `loadBalancer`, `userDefinedRouting`, `managedNATGateway` and `userAssignedNATGateway`. Defaults to `loadBalancer`. More information on supported migration paths for `outbound_type` can be found in [this documentation](https://learn.microsoft.com/azure/aks/egress-outboundtype#updating-outboundtype-after-cluster-creation).
 
-* `pod_cidr` - (Optional) The CIDR to use for pod IP addresses. This field can only be set when `network_plugin` is set to `kubenet` or `network_plugin_mode` is set to `overlay`. Changing this forces a new resource to be created.
+* `pod_cidr` - (Optional) The CIDR to use for pod IP addresses. This field can only be set when `network_plugin` is set to `kubenet` or `network_plugin_mode` is set to `overlay`. Changing an non-empty value forces a new resource to be created.
 
-* `pod_cidrs` - (Optional) A list of CIDRs to use for pod IP addresses. For single-stack networking a single IPv4 CIDR is expected. For dual-stack networking an IPv4 and IPv6 CIDR are expected. Changing this forces a new resource to be created.
+* `pod_cidrs` - (Optional) A list of CIDRs to use for pod IP addresses. For single-stack networking a single IPv4 CIDR is expected. For dual-stack networking an IPv4 and IPv6 CIDR are expected. Changing an non-empty value forces a new resource to be created.
 
 * `service_cidr` - (Optional) The Network Range used by the Kubernetes service. Changing this forces a new resource to be created.