checkpointer: ignore Affinity within podspec (w/ tests)

cmd/checkpoint/README.md

@@ -17,7 +17,7 @@ This is accomplished by managing checkpoints as static pod manifests:
 ## Use
 
 Any pod which contains the `checkpointer.alpha.coreos.com/checkpoint=true` annotation will be considered a viable "parent pod" which should be checkpointed.
-The parent pod cannot itself be a static pod, and is not a checkpoint itself.
+The parent pod cannot itself be a static pod, and is not a checkpoint itself. Affinity is not supported for a pod, and any pod labelled with the checkpoint annotation will be checkpointed.
 
 Checkpoints are denoted by the `checkpointer.alpha.coreos.com/checkpoint-of` annotation. This annotation will point to the parent of this checkpoint by pod name.
 

pkg/checkpoint/pod.go

@@ -63,6 +63,9 @@ func sanitizeCheckpointPod(cp *v1.Pod) *v1.Pod {
 	cp.Spec.ServiceAccountName = ""
 	cp.Spec.DeprecatedServiceAccount = ""
 
+	// Remove affinity
+	cp.Spec.Affinity = nil
+
 	// Sanitize the volumes
 	for i := range cp.Spec.Volumes {
 		v := &cp.Spec.Volumes[i]