<p>I try to create an autoscaled container cluster on GKE.
When I use the "--enable-autoscaling" option (like the documentation indicates here : <a href="https://cloud.google.com/container-engine/docs/clusters/operations#create_a_cluster_with_autoscaling" rel="nofollow">https://cloud.google.com/container-engine/docs/clusters/operations#create_a_cluster_with_autoscaling</a>) :</p>

<pre><code>$ gcloud container clusters create mycluster --zone $GOOGLE_ZONE --num-nodes=3 --enable-autoscaling --min-nodes=2 --max-nodes=5
</code></pre>

<p>but the MIG (Managed Instanced Group) is not displayed as 'autoscaled' as shown by both the web interface and the result of the following command :</p>

<pre><code>$ gcloud compute instance-groups managed list
NAME             SIZE   TARGET_SIZE   AUTOSCALED
gke-mycluster... 3      3             no
</code></pre>

<p>Why ?</p>

<p>Then, I tried the other way indicated in the kubernetes docs (<a href="http://kubernetes.io/docs/admin/cluster-management/#cluster-autoscaling" rel="nofollow">http://kubernetes.io/docs/admin/cluster-management/#cluster-autoscaling</a>) but got an error caused by the '=true' apparently :</p>

<pre><code>$ gcloud container clusters create mytestcluster --zone=$GOOGLE_ZONE --enable-autoscaling=true --min-nodes=2 --max-nodes=5 --num-nodes=3
usage: gcloud container clusters update  NAME [optional flags]
ERROR: (gcloud.container.clusters.update) argument --enable-autoscaling: ignored explicit argument 'true'
</code></pre>

<p>Is the doc wrong on this ?
Here is my gcloud version results :</p>

<pre><code>$ gcloud version
Google Cloud SDK 120.0.0
beta 2016.01.12
bq 2.0.24
bq-nix 2.0.24
core 2016.07.29
core-nix 2016.03.28
gcloud 
gsutil 4.20
gsutil-nix 4.18
kubectl 
kubectl-linux-x86_64 1.3.3
</code></pre>

<p>Last precision : the autoscaler seems 'on' in the description on the cluster :</p>

<pre><code>$ gcloud container clusters describe  mycluster | grep auto -A 3
- autoscaling:
    enabled: true
    maxNodeCount: 5
    minNodeCount: 2
</code></pre>

<p>Any idea to explain this behaviour please ?</p>

<p>Kubernetes cluster autoscaling does not use the Managed Instance Group autoscaler. It runs a <code>cluster-autoscaler</code> controller on the Kubernetes master that uses Kubernetes-specific signals to scale your nodes. <a href="https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler" rel="nofollow noreferrer">The code</a> is in the <code>autoscaler</code> repo if you want more info.</p>

<p>I've also sent out <a href="https://github.com/kubernetes/kubernetes.github.io/pull/1211" rel="nofollow noreferrer">a PR</a> to fix the invalid flag usage in the autoscaling docs. Thanks for catching that!</p>
