Module version nodes' label management (#347)

This PR adds the management of the a module version labels management
per node. It is done in a dedicated controller, which listens on the
changes of the module version labels on the nodes. Once such a change is
detected, the reconciliation flow is as following:
1) get all the module version labels of the node (module version,
   module_loader version, device-plugin version)
2) sort the labels per their module-name/namespace. Result: slice
   of structure (one structure per module), that holds the values
   of module/module-loader/device-lugin labels for that particular module
3) Per each module, based on a static action-table, determine what is the next
   action should be: none, adding label, deleting label. Per module it will always
   be only one label that will either be added or deleted
4) Gather all labels to be added/deleted for all the modules and update node in
   one operation

Chnages in code:
1) new controller
2) static action table for that controller
3) adding filter function to trigger the controller only on changes
   to module version labels
4) mocks and unit-tests

Author: yevgeny-shnaidman

cmd/manager/main.go

@@ -159,6 +159,10 @@ func main() {
 		cmd.FatalError(setupLogger, err, "unable to create controller", "name", controllers.PodNodeModuleReconcilerName)
 	}
 
+	if err = controllers.NewNodeLabelModuleVersionReconciler(client).SetupWithManager(mgr); err != nil {
+		cmd.FatalError(setupLogger, err, "unable to create controller", "name", controllers.NodeLabelModuleVersionReconcilerName)
+	}
+
 	preflightStatusUpdaterAPI := statusupdater.NewPreflightStatusUpdater(client)
 	preflightAPI := preflight.NewPreflightAPI(client, buildAPI, signAPI, registryAPI, preflightStatusUpdaterAPI, kernelAPI)
 

controllers/mock_node_label_module_version_reconciler.go

@@ -0,0 +1,66 @@
+package controllers
+
+import "github.com/kubernetes-sigs/kernel-module-management/internal/utils"
+
+const (
+	labelMissing   = "missing"
+	labelPresent   = "present"
+	labelDifferent = "different"
+
+	addAction    = "add"
+	deleteAction = "delete"
+	noneAction   = "none"
+)
+
+type labelActionKey struct {
+	module       string
+	moduleLoader string
+	devicePlugin string
+}
+
+type labelAction struct {
+	getLabelName func(string, string) string
+	action       string
+}
+
+var labelActionTable = map[labelActionKey]labelAction{
+	labelActionKey{
+		module:       labelMissing,
+		moduleLoader: labelMissing,
+		devicePlugin: labelMissing}: labelAction{getLabelName: nil, action: noneAction},
+
+	labelActionKey{
+		module:       labelMissing,
+		moduleLoader: labelPresent,
+		devicePlugin: labelPresent}: labelAction{getLabelName: utils.GetDevicePluginVersionLabelName, action: deleteAction},
+
+	labelActionKey{
+		module:       labelMissing,
+		moduleLoader: labelPresent,
+		devicePlugin: labelMissing}: labelAction{getLabelName: utils.GetModuleLoaderVersionLabelName, action: deleteAction},
+
+	labelActionKey{
+		module:       labelPresent,
+		moduleLoader: labelMissing,
+		devicePlugin: labelMissing}: labelAction{getLabelName: utils.GetModuleLoaderVersionLabelName, action: addAction},
+
+	labelActionKey{
+		module:       labelPresent,
+		moduleLoader: labelPresent,
+		devicePlugin: labelMissing}: labelAction{getLabelName: utils.GetDevicePluginVersionLabelName, action: addAction},
+
+	labelActionKey{
+		module:       labelPresent,
+		moduleLoader: labelPresent,
+		devicePlugin: labelPresent}: labelAction{getLabelName: nil, action: noneAction},
+
+	labelActionKey{
+		module:       labelPresent,
+		moduleLoader: labelDifferent,
+		devicePlugin: labelDifferent}: labelAction{getLabelName: utils.GetDevicePluginVersionLabelName, action: deleteAction},
+
+	labelActionKey{
+		module:       labelPresent,
+		moduleLoader: labelDifferent,
+		devicePlugin: labelMissing}: labelAction{getLabelName: utils.GetModuleLoaderVersionLabelName, action: deleteAction},
+}