Use more efficient "e2" machine types

[bkramer]

Summary

These are ~30% cheaper, but sadly don't support GPUs.

[kuhnel]

Nice. I'll give that a try tomorrow!

buildbot/google/terraform/main.tf

resource "google_container_cluster" "primary" {
   min_master_version = "1.16"
 
   # one node is enough (at the moment)
   initial_node_count = 1
 
   node_config {
     # FIXME(kuhnel): turn this into a private cluster, without external IP
     # We need at least 2 vCPU to run all kubernetes services
-    machine_type = "n1-standard-2"
+    machine_type = "e2-medium"
     # use preemptible, as this saves costs
     preemptible = true
   }
 
 }
 
 # Create machines for mlir-nvidia
 # Note: The buildbot mlir-nividia is deployed using a kubernetes file. See
resource "google_container_node_pool" "windows_32core_pool_nodes" {
   autoscaling {
     min_node_count = 0
     max_node_count = 1
   }
   
   node_config {
     # use preemptible, as this saves costs
     preemptible  = true
-    machine_type = "n1-highcpu-32"
+    machine_type = "e2-highcpu-32"
     # Windows deployments tend to require more disk space, so using 300GB here.
     disk_size_gb = 300
     # FIXME: test if SSDs are actually faster than HDDs for our use case
     disk_type = "pd-ssd"
 
     # Configure Windows image. As Windows is picky about the combination of
     # host and container OS versions, this must be compatible with the version
     # in your container. Recommondation: Use LTSC for long-term stability.