I'm pretty new to kubernetes, not so much with docker.

I've been working through the example but I am stuck with the autoscaler, (which doesn't seem to scale).

I am working through the example here <https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/#step-one-run--expose-php-apache-server>

You'll find the build at the bottom

`kubectl create -f https://k8s.io/docs/tasks/run-application/hpa-php-apache.yaml`

Which looks like this 

```
apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
  name: php-apache
  namespace: default
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: php-apache
  minReplicas: 1
  maxReplicas: 10
  targetCPUUtilizationPercentage: 50

```

`kubectl get hba` shows

```
NAME         REFERENCE               TARGETS         MINPODS   MAXPODS   REPLICAS   AGE
php-apache   Deployment/php-apache   <unknown>/50%   1         10        0          7s

```

Clue in the `<unknown>` section.

Then `kubectl describe hba` shows

```
Name:                                                  php-apache
Namespace:                                             default
Labels:                                                <none>
Annotations:                                           <none>
CreationTimestamp:                                     Sat, 14 Apr 2018 23:05:05 +0100
Reference:                                             Deployment/php-apache
Metrics:                                               ( current / target )
  resource cpu on pods  (as a percentage of request):  <unknown> / 50%
Min replicas:                                          1
Max replicas:                                          10
Conditions:
  Type         Status  Reason          Message
  ----         ------  ------          -------
  AbleToScale  False   FailedGetScale  the HPA controller was unable to get the target's current scale: deployments/scale.extensions "php-apache" not found
Events:
  Type     Reason          Age                From                       Message
  ----     ------          ----               ----                       -------
  Warning  FailedGetScale  12s (x14 over 6m)  horizontal-pod-autoscaler  deployments/scale.extensions "php-apache" not found

```

So then I manually add it in with...

`kubectl run php-apache --image=k8s.gcr.io/hpa-example --requests=cpu=200m --expose --port=80`

Then if i run `kubectl describe hpa` again I get this error..

```
Name:                                                  php-apache
Namespace:                                             default
Labels:                                                <none>
Annotations:                                           <none>
CreationTimestamp:                                     Sat, 14 Apr 2018 23:05:05 +0100
Reference:                                             Deployment/php-apache
Metrics:                                               ( current / target )
  resource cpu on pods  (as a percentage of request):  <unknown> / 50%
Min replicas:                                          1
Max replicas:                                          10
Conditions:
  Type           Status  Reason                   Message
  ----           ------  ------                   -------
  AbleToScale    True    SucceededGetScale        the HPA controller was able to get the target's current scale
  ScalingActive  False   FailedGetResourceMetric  the HPA was unable to compute the replica count: unable to get metrics for resource cpu: unable to fetch metrics from API: the server could not find the requested resource (get pods.metrics.k8s.io)
Events:
  Type     Reason                        Age                From                       Message
  ----     ------                        ----               ----                       -------
  Warning  FailedGetScale                1m (x21 over 11m)  horizontal-pod-autoscaler  deployments/scale.extensions "php-apache" not found
  Warning  FailedGetResourceMetric       8s (x2 over 38s)   horizontal-pod-autoscaler  unable to get metrics for resource cpu: unable to fetch metrics from API: the server could not find the requested resource (get pods.metrics.k8s.io)
  Warning  FailedComputeMetricsReplicas  8s (x2 over 38s)   horizontal-pod-autoscaler  failed to get cpu utilization: unable to get metrics for resource cpu: unable to fetch metrics from API: the server could not find the requested resource (get pods.metrics.k8s.io)

```