feat: add SkipIncompleteLateInitializeCheck (#606)

Description of changes:
When a field is marked for lateInitialize, the controller tries to
ensure that field is never nil.
If by chance the field is nil, the controller will reconcile every 5
seconds until the field is no longer nil.

Although we want certain fields lateInitialized, we don't expect them to
be nonNil.

In the example of RDS DBInstance, DBInstance contains
PerformanceInsightsKMSID, that we want to lateInitialize only when
PerformanceInsights is Enabled.

For now this change only allows us the incomplete check, but moving
forward, we may want to add certain conditions, to skip or not to
skip...

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Author: michaelhtm

pkg/config/field.go

@@ -318,6 +318,17 @@ type LateInitializeConfig struct {
 	// MaxBackoffSeconds provide the maximum allowed backoff when retrying late initialization after an
 	// unsuccessful attempt.
 	MaxBackoffSeconds int `json:"max_backoff_seconds"`
+	// SkipIncompleteCheck skips the LateInitialization incomplete check for resources.
+	// NOTE: (michaelhtm) This skip is best used on resource fields we're sure will be set before being synced
+	// eg. A resource is marked as synced before the field is lateInitialized, we wouldn't want to wait until
+	// the next drift detection for the field to be set
+	SkipIncompleteCheck *SkipIncompleteLateInitializeCheckConfig `json:"skip_incomplete_check,omitempty"`
+}
+
+// SkipIncompleteLateInitializeCheckConfig is a config that defines the scenarios in which
+// we would want to skip lateInitialization.
+// TODO: (michaelhtm) Populate this struct with conditions...?
+type SkipIncompleteLateInitializeCheckConfig struct {
 }
 
 // ReferencesConfig contains the instructions for how to add the referenced resource

pkg/generate/code/late_initialize.go

@@ -276,7 +276,10 @@ func IncompleteLateInitialization(
 	indent := strings.Repeat("\t", indentLevel)
 	var lateInitFieldNames []string
 	lateInitConfigs := cfg.GetLateInitConfigs(r.Names.Original)
-	for fieldName := range lateInitConfigs {
+	for fieldName, lateInitConfig := range lateInitConfigs {
+		if lateInitConfig.SkipIncompleteCheck != nil {
+			continue
+		}
 		lateInitFieldNames = append(lateInitFieldNames, fieldName)
 	}
 	if len(lateInitFieldNames) == 0 {