Invalidate discovery cache before migration commands

This change updates the migration commands to invalidate and refetch
the cached discovery information on disk.  This makes it so that the
REST mapper will never use stale discovery data.

Signed-off-by: Monis Khan <[email protected]>

Author: enj

Diff for: pkg/oc/cli/admin/migrate/migrator.go

@@ -210,14 +210,16 @@ func (o *ResourceOptions) Complete(f kcmdutil.Factory, c *cobra.Command) error {
 		}
 	}
 
-	clientConfig, err := f.ToRESTConfig()
-	if err != nil {
-		return err
-	}
-	discoveryClient, err := discovery.NewDiscoveryClientForConfig(clientConfig)
+	// use the factory's caching discovery client
+	discoveryClient, err := f.ToDiscoveryClient()
 	if err != nil {
 		return err
 	}
+	// but invalidate its cache to force it to fetch the latest data
+	discoveryClient.Invalidate()
+	// and do a no-op call to cause the latest data to be written to disk
+	_, _ = discoveryClient.ServerResources()
+	// so that the REST mapper will never use stale discovery data
 	mapper, err := f.ToRESTMapper()
 	if err != nil {
 		return err
@@ -725,7 +727,7 @@ func DefaultRetriable(info *resource.Info, err error) error {
 // represented.
 // TODO: add a field to APIResources for "virtual" (or that points to the canonical resource).
 // TODO: fallback to the scheme when discovery is not possible.
-func FindAllCanonicalResources(d discovery.DiscoveryInterface, m meta.RESTMapper) ([]schema.GroupResource, error) {
+func FindAllCanonicalResources(d discovery.ServerResourcesInterface, m meta.RESTMapper) ([]schema.GroupResource, error) {
 	set := make(map[schema.GroupResource]struct{})
 	all, err := d.ServerResources()
 	if err != nil {