remove cache from clusterapi infra machine template

cluster-autoscaler/cloudprovider/clusterapi/clusterapi_controller.go

@@ -73,11 +73,6 @@ type infrastructureTemplateCacheEntry struct {
 	template   *unstructured.Unstructured
 }
 
-// infrastructureTemplateCache holds infrastructure machine templates and
-// their time to live values. It is used by the getInfrastructureResource
-// function.
-var infrastructureTemplateCache map[string]infrastructureTemplateCacheEntry = map[string]infrastructureTemplateCacheEntry{}
-
 // machineController watches for Nodes, Machines, MachineSets and
 // MachineDeployments as they are added, updated and deleted on the
 // cluster. Additionally, it adds indices to the node informers to
@@ -727,27 +722,7 @@ func (c *machineController) allowedByAutoDiscoverySpecs(r *unstructured.Unstruct
 }
 
 // Get an infrastructure machine template given its GVR, name, and namespace.
-// This function exists so that we can implement a cache for the
-// infrastructure template objects. A local cache is used in favor of the
-// client-go informers because of the frequency of read requests combined
-// with the fact that the infrastructure template will not be updated
-// frequently (if at all). In practice, the autoscaler can make calls to
-// the API server at a high frequency, which results in many calls being
-// throttled on the client-side. To reduce the amount of throttling we keep
-// an in-memory cache of infrastructure templates. The cache has a time to
-// live on any entry of 1 minute.
 func (c *machineController) getInfrastructureResource(resource schema.GroupVersionResource, name string, namespace string) (*unstructured.Unstructured, error) {
-	// this cache key is only used internally, join the GVR+name+namespace
-	cachekey := strings.Join([]string{resource.String(), name, namespace}, "")
-	if entry, ok := infrastructureTemplateCache[cachekey]; ok {
-		// if the infrastructure template exists in the cache and is under the time to live, return it
-		if time.Now().Before(entry.timeToLive) {
-			return entry.template, nil
-		}
-	}
-
-	// if the infrastructure template does not exist in the cache or is older
-	// than the time to live, we get a fresh record from the API server
 	infra, err := c.managementClient.
 		Resource(resource).
 		Namespace(namespace).
@@ -761,11 +736,5 @@ func (c *machineController) getInfrastructureResource(resource schema.GroupVersi
 		return nil, err
 	}
 
-	// update the cache with the new record
-	infrastructureTemplateCache[cachekey] = infrastructureTemplateCacheEntry{
-		timeToLive: time.Now().Add(cacheEntryTimeToLive),
-		template:   infra,
-	}
-
 	return infra, err
 }