Small documentation changes to warn users about deploying VPA with leader election on GKE.

vertical-pod-autoscaler/FAQ.md

@@ -205,11 +205,11 @@ Name | Type | Description | Default
 `memory-histogram-decay-half-life` | Duration | The amount of time it takes a historical memory usage sample to lose half of its weight. In other words, a fresh usage sample is twice as 'important' as one with age equal to the half life period. | model.DefaultMemoryHistogramDecayHalfLife
 `cpu-histogram-decay-half-life` | Duration | The amount of time it takes a historical CPU usage sample to lose half of its weight. | model.DefaultCPUHistogramDecayHalfLife
 `cpu-integer-post-processor-enabled` | Bool | Enable the CPU integer recommendation post processor | false
-`leader-elect` | Bool | Start a leader election client and gain leadership before executing the main loop. Enable this when running replicated components for high availability. | false
+`leader-elect` | Bool | Start a leader election client and gain leadership before executing the main loop. Enable this when running replicated components for high availability. **If enabling this in GKE, you MUST also manually set the `--leader-elect-resource-name` flag.** | false
 `leader-elect-lease-duration` | Duration | The duration that non-leader candidates will wait after observing a leadership renewal until attempting to acquire leadership of a led but unrenewed leader slot. This is effectively the maximum duration that a leader can be stopped before it is replaced by another candidate. This is only applicable if leader election is enabled. | 15s
 `leader-elect-renew-deadline` | Duration | The interval between attempts by the acting master to renew a leadership slot before it stops leading. This must be less than the lease duration. This is only applicable if leader election is enabled. | 10s
 `leader-elect-resource-lock` | String | The type of resource object that is used for locking during leader election. Supported options are 'leases', 'endpointsleases' and 'configmapsleases'. | "leases"
-`leader-elect-resource-name` | String | The name of resource object that is used for locking during leader election. | "vpa-recommender"
+`leader-elect-resource-name` | String | The name of resource object that is used for locking during leader election. **If using GKE, you must set this value to something OTHER than "vpa-recommender", for example "vpa-recommender-lease".** | "vpa-recommender"
 `leader-elect-resource-namespace` | String | The namespace of resource object that is used for locking during leader election. | "kube-system"
 `leader-elect-retry-period` | Duration | The duration the clients should wait between attempting acquisition and renewal of a leadership. This is only applicable if leader election is enabled. | 2s
 

vertical-pod-autoscaler/README.md

@@ -420,6 +420,10 @@ Using it in conjunction with `--ignored-vpa-object-namespaces=kube-system` or `-
   size, available quota) and cause **pods to go pending**. This can be partly
   addressed by using VPA together with [Cluster Autoscaler](https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/FAQ.md#basics).
 * Multiple VPA resources matching the same pod have undefined behavior.
+* Running the vpa-recommender with leader election enabled (`--leader-elect=true`) in a GKE cluster
+  causes contention with a lease called `vpa-recommender` held by the GKE system component of the
+  same name. To run your own VPA in GKE, make sure to specify a different lease name using
+  `--leader-elect-resource-name=vpa-recommender-lease` (or specify your own lease name).
 
 # Related links