[awi-ciroh] Enable node placeholders

config/clusters/awi-ciroh/workshop.values.yaml

@@ -1,4 +1,10 @@
 basehub:
+  # Enable node placeholders, to ensure capacity at first login
+  nodePlaceholder:
+    enabled: true
+    nodeSelector:
+      node.kubernetes.io/instance-type: n4-standard-16
+    replicas: 0
   jupyterhub-home-nfs:
     nodeSelector:
       cloud.google.com/gke-nodepool: workshop-temp-nfs
@@ -13,7 +19,12 @@ basehub:
       config:
         QuotaManager:
           hard_quota: 40 # in GiB
+  # Ensure that placeholder nodes are densely packed, making instance-type
+  # easier to scale down.
   jupyterhub:
+    scheduling:
+      userScheduler:
+        enabled: true
     custom:
       singleuserAdmin:
         extraVolumeMounts:

helm-charts/basehub/templates/deployment-node-placeholder.yaml

@@ -12,11 +12,13 @@ spec:
     matchLabels:
       app: jupyterhub
       component: node-placeholder
+  {{- if .Values.nodePlaceholder.wait }}
   updateStrategy:
     type: RollingUpdate
     rollingUpdate:
       maxUnavailable: 100%
       maxSurge: 0
+  {{- end }}
   template:
     metadata:
       labels:

helm-charts/basehub/values.schema.yaml

@@ -127,6 +127,7 @@ properties:
       - tolerations
       - extraTolerations
       - pauseContainer
+      - wait
     properties:
       enabled:
         type: boolean
@@ -151,6 +152,8 @@ properties:
         description: |
           Tolerations allow a pod to be scheduled on nodes with taints.
       extraTolerations: *tolerations-spec
+      wait:
+        type: boolean
   inClusterNFS:
     type: object
     additionalProperties: false

helm-charts/basehub/values.yaml

@@ -357,6 +357,8 @@ nodePlaceholder:
       value: user
       effect: NoSchedule
   extraTolerations: []
+  # Don't wait for the placeholders to be ready
+  wait: false
 
 # Use NFS provided by an in cluster server with the nfs-external-provisioner chart
 inClusterNFS: