I've configured a kubernetes cluster with metrics-server (as an aggregated apiserver) replacing heapster. kubectl top works fine, as do the raw endpoints in the metrics.k8s.io/v1beta1 api group. HPA, however, does not. controller-manager logs show the following errors (and no others):

E1008 10:45:18.462447       1 horizontal.go:188] failed to compute desired number of replicas based on listed metrics for Deployment/kube-system/nginx: failed to get cpu utilization: missing request for cpu on container nginx in pod kube-system/nginx-64f497f8fd-7kr96
I1008 10:45:18.462511       1 event.go:221] Event(v1.ObjectReference{Kind:"HorizontalPodAutoscaler", Namespace:"kube-system", Name:"nginx", UID:"387f256e-cade-11e8-9cfa-525400c042d5", APIVersion:"autoscaling/v2beta1", ResourceVersion:"3367", FieldPath:""}): type: 'Warning' reason: 'FailedGetResourceMetric' missing request for cpu on container nginx in pod kube-system/nginx-64f497f8fd-7kr96
I1008 10:45:18.462529       1 event.go:221] Event(v1.ObjectReference{Kind:"HorizontalPodAutoscaler", Namespace:"kube-system", Name:"nginx", UID:"387f256e-cade-11e8-9cfa-525400c042d5", APIVersion:"autoscaling/v2beta1", ResourceVersion:"3367", FieldPath:""}): type: 'Warning' reason: 'FailedComputeMetricsReplicas' failed to get cpu utilization: missing request for cpu on container nginx in pod kube-system/nginx-64f497f8fd-7kr96

metrics-server spec:

spec:
  containers:
  - args:
    - --kubelet-preferred-address-types=InternalIP
    image: k8s.gcr.io/metrics-server-amd64:v0.3.1
    imagePullPolicy: Always
    name: metrics-server
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
    volumeMounts:
    - mountPath: /tmp
      name: tmp-dir
  dnsPolicy: ClusterFirst
  restartPolicy: Always
  schedulerName: default-scheduler
  securityContext: {}
  serviceAccount: metrics-server
  serviceAccountName: metrics-server
  terminationGracePeriodSeconds: 30
  volumes:
  - emptyDir: {}
    name: tmp-dir

controller-manager is running with

--horizontal-pod-autoscaler-use-rest-clients="true"

k8s version 1.11.3

Any ideas?