Add pod anti-affinity to Deckhand

This PS adds pod anti-affinity to deckhand pods,
so that the scheduler can constrain pods against labels on other pods
running on the node. The default soft rule is in place so that if the
scheduler can’t satisfy the requirement, the pod will still
be scheduled.

Change-Id: Icab673726d0473662ccf45c4c576fe20912a1260

charts/deckhand/templates/deployment.yaml

@@ -40,6 +40,8 @@ spec:
     spec:
       serviceAccountName: {{ $serviceAccountName }}
 {{ dict "envAll" $envAll "application" "deckhand" | include "helm-toolkit.snippets.kubernetes_pod_security_context" | indent 6 }}
+      affinity:
+{{ tuple $envAll "deckhand" "api" | include "helm-toolkit.snippets.kubernetes_pod_anti_affinity" | indent 8 }}
       nodeSelector:
         {{ .Values.labels.api.node_selector_key }}: {{ .Values.labels.api.node_selector_value }}
       terminationGracePeriodSeconds: {{ .Values.pod.lifecycle.termination_grace_period.deckhand.timeout | default "30" }}

charts/deckhand/values.yaml

@@ -354,6 +354,12 @@ pod:
     termination_grace_period:
       deckhand:
         timeout: 30
+  affinity:
+    anti:
+      type:
+        default: preferredDuringSchedulingIgnoredDuringExecution
+      topologyKey:
+        default: kubernetes.io/hostname
   replicas:
     deckhand: 1
   resources: