Merge pull request #23914 from sky-uk/make-etcd-cache-size-configurable

Automatic merge from submit-queue

Make etcd cache size configurable

Instead of the prior 50K limit, allow users to specify a more sensible size for their cluster.

I'm not sure what a sensible default is here. I'm still experimenting on my own clusters. 50 gives me a 270MB max footprint. 50K caused my apiserver to run out of memory as it exceeded >2GB. I believe that number is far too large for most people's use cases.

There are some other fundamental issues that I'm not addressing here:
- Old etcd items are cached and potentially never removed (it stores using modifiedIndex, and doesn't remove the old object when it gets updated)
- Cache isn't LRU, so there's no guarantee the cache remains hot. This makes its performance difficult to predict. More of an issue with a smaller cache size.
- 1.2 etcd entries seem to have a larger memory footprint (I never had an issue in 1.1, even though this cache existed there). I suspect that's due to image lists on the node status.

This is provided as a fix for #23323

docs/admin/kube-apiserver.md

@@ -67,6 +67,7 @@ kube-apiserver
       --cloud-provider="": The provider for cloud services.  Empty string for no provider.
       --cors-allowed-origins=[]: List of allowed origins for CORS, comma separated.  An allowed origin can be a regular expression to support subdomain matching.  If this list is empty CORS will not be enabled.
       --delete-collection-workers=1: Number of workers spawned for DeleteCollection call. These are used to speed up namespace cleanup.
+      --deserialization-cache-size=50000: Number of deserialized json objects to cache in memory.
       --enable-swagger-ui[=false]: Enables swagger ui on the apiserver at /swagger-ui
       --etcd-cafile="": SSL Certificate Authority file used to secure etcd communication
       --etcd-certfile="": SSL certification file used to secure etcd communication
@@ -116,7 +117,7 @@ kube-apiserver
       --watch-cache-sizes=[]: List of watch cache sizes for every resource (pods, nodes, etc.), comma separated. The individual override format: resource#size, where size is a number. It takes effect when watch-cache is enabled.
 ```
 
-###### Auto generated by spf13/cobra on 22-Mar-2016
+###### Auto generated by spf13/cobra on 12-Apr-2016
 
 
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