Change Azure default controller_type and worker_type

* Change default controller_type to Standard_B2s. A B2s is cheaper
by $17/month and provides 2 vCPU, 4GB RAM (vs 1 vCPU, 3.5GB RAM)
* Change default worker_type to Standard_DS1_v2. F1 was the previous
generation. The DS1_v2 is newer, similar cost, more memory, and still
supports Low Priority mode, if desired

CHANGES.md

@@ -8,6 +8,13 @@ Notable changes between versions.
 * Update etcd from v3.3.15 to [v3.4.0](https://github.com/etcd-io/etcd/releases/tag/v3.4.0)
 * Recommend updating `terraform-provider-ct` plugin from v0.3.2 to [v0.4.0](https://github.com/poseidon/terraform-provider-ct/releases/tag/v0.4.0)
 
+#### Azure
+
+* Change default `controller_type` to `Standard_B2s`
+  * `B2s` is cheaper by $17/month and provides 2 vCPU, 4GB RAM
+* Change default `worker_type` to `Standard_DS1_v2`
+  * `F1` is previous generation. `DS1_v2` is newer, similar cost, and supports Low Priority mode
+
 #### Addons
 
 * Update Grafana from v6.3.3 to v6.3.5

azure/container-linux/kubernetes/variables.tf

@@ -36,13 +36,13 @@ variable "worker_count" {
 
 variable "controller_type" {
   type        = string
-  default     = "Standard_DS1_v2"
+  default     = "Standard_B2s"
   description = "Machine type for controllers (see `az vm list-skus --location centralus`)"
 }
 
 variable "worker_type" {
   type        = string
-  default     = "Standard_F1"
+  default     = "Standard_DS1_v2"
   description = "Machine type for workers (see `az vm list-skus --location centralus`)"
 }