add update-strategy=skip

docs/apply.md

@@ -26,11 +26,12 @@ Possible values `` (default), `fallback-on-update`. In some cases creation of a
 
 `kapp.k14s.io/update-strategy` annotation controls update behaviour
 
-Possible values: `` (default), `fallback-on-replace`, `always-replace`. In some cases entire resources or subset resource fields are immutable which forces kapp users to specify how to apply wanted update.
+Possible values: `` (default), `fallback-on-replace`, `always-replace`, `skip`. In some cases entire resources or subset resource fields are immutable which forces kapp users to specify how to apply wanted update.
 
 - `` means to issue plain update call
 - `fallback-on-replace` causes kapp to fallback to resource replacement if update call results in `Invalid` error. Note that if resource is replaced (= delete + create), it may be negatively affected (loss of persistent data, loss of availability, etc.). For example, if Deployment or DaemonSet is first deleted and then created then associated Pods will be recreated as well, but all at the same time (even if rolling update is enabled), which likely causes an availability gap.
 - `always-replace` causes kapp to always delete and then create resource (See note above as well.)
+- `skip` causes kapp to not apply update (it will show up in a diff next time)
 
 #### kapp.k14s.io/delete-strategy
 

pkg/kapp/clusterapply/add_or_update_change.go

@@ -19,6 +19,7 @@ const (
 	updateStrategyPlainAnnValue             ClusterChangeApplyStrategyOp = ""
 	updateStrategyFallbackOnReplaceAnnValue ClusterChangeApplyStrategyOp = "fallback-on-replace"
 	updateStrategyAlwaysReplaceAnnValue     ClusterChangeApplyStrategyOp = "always-replace"
+	updateStrategySkipAnnValue              ClusterChangeApplyStrategyOp = "skip"
 )
 
 type AddOrUpdateChangeOpts struct {
@@ -74,6 +75,9 @@ func (c AddOrUpdateChange) ApplyStrategy() (ApplyStrategy, error) {
 		case updateStrategyAlwaysReplaceAnnValue:
 			return UpdateAlwaysReplaceStrategy{c}, nil
 
+		case updateStrategySkipAnnValue:
+			return UpdateSkipStrategy{c}, nil
+
 		default:
 			return nil, fmt.Errorf("Unknown update strategy: %s", strategy)
 		}
@@ -338,3 +342,13 @@ func (c UpdateAlwaysReplaceStrategy) Op() ClusterChangeApplyStrategyOp {
 func (c UpdateAlwaysReplaceStrategy) Apply() error {
 	return c.aou.replace()
 }
+
+type UpdateSkipStrategy struct {
+	aou AddOrUpdateChange
+}
+
+func (c UpdateSkipStrategy) Op() ClusterChangeApplyStrategyOp {
+	return updateStrategySkipAnnValue
+}
+
+func (c UpdateSkipStrategy) Apply() error { return nil }