updating to include #6095

CHANGELOG.md

@@ -1,6 +1,29 @@
 ## 2.5.0 (Unreleased)
-## 2.4.0 (April 02, 2020)
 
+BREAKING CHANGES:
+
+* Azure Kubernetes Service
+	* Due to a breaking change in the AKS API, the `azurerm_kubernetes_cluster` resource features a significant behavioural change where creating Mixed-Mode Authentication clusters (e.g. using a Service Principal with a Managed Identity) is no longer supported.
+	* The AKS Team have confirmed that existing clusters will be updated by the Azure API to use only MSI when a change is made to the Cluster (but not the Node Pool). Whilst Terraform could perform this automatically some environments have restrictions on which tags can be added/removed - as such this operation will need to be performed out-of-band. Instead, upon detecting a Mixed-Mode Cluster which has not yet been updated - or upon detecting a former Mixed-Mode Cluster where the Terraform Configuration still contains a `service_principal` block - Terraform will output instructions on how to proceed.
+	* `azurerm_kubernetes_cluster_node_pool` - clusters with auto-scale disabled must ensure that `min_count` and `max_count` are set to `null` (or omitted) rather than `0` (since 0 isn't a valid value for these fields).
+
+NOTES:
+
+* There's currently a bug in the Azure Kubernetes Service (AKS) API where the Tags on Node Pools are returned in the incorrect case - [this bug is being tracked in this issue](https://github.com/Azure/azure-rest-api-specs/issues/8952). This affects the `tags` field within the `default_node_pool` block for `azurerm_kubernetes_clusters` and the `tags` field for the `azurerm_kubernetes_cluster_node_pool` resource.
+
+IMPROVEMENTS:
+
+* dependencies: updating to use version `2020-02-01` of the Containers API [GH-6095]
+* `azurerm_kubernetes_cluster` - making the `service_principal` block optional - so it's now possible to create MSI-only clusters [GH-6095]
+* `azurerm_kubernetes_cluster` - making the `windows_profile` block computed as Windows credentials are now generated by Azure if unspecified [GH-6095]
+
+BUG FIXES:
+
+* `azurerm_kubernetes_cluster` - requiring that `min_count` and `max_count` are set to `null` rather than `0` when auto-scaling is disabled [GH-6095]
+* `azurerm_kubernetes_cluster` - ensuring that a value for `node_count` is always passed to the API to match a requirement in the API [GH-6095]
+* `azurerm_kubernetes_cluster` - ensuring that `tags` are set into the state for the `default_node_pool` [GH-6095]
+
+## 2.4.0 (April 02, 2020)
 
 FEATURES: