Re-execute full validation for AppNetworkConfig once pending NIs are …

…ready

When an application network configuration depends on a network instance (NI)
that is either missing or in an error state, zedrouter flags the AppNetworkStatus
with AwaitNetworkInstance. It then waits until the network instance becomes
available and is activated without errors before proceeding with the activation
of the application network.

However, conditions may change while the application is waiting for the network
instance to be available. For instance, another application with conflicting
port forwarding rules could have been deployed during this time, which would
necessitate preventing the activation of this app's network.

To address this, we adopt the approach used in zedrouter.retryFailedAppNetworks(),
where the entire pubsub handler is re-executed to repeat the full validation process.
The handler is idempotent, ensuring operations like AppNum allocation reuse
previously set values.

Signed-off-by: Milan Lenco <milan@zededa.com>
(cherry picked from commit 06454fa)

pkg/pillar/cmd/zedrouter/appnetwork.go

@@ -266,7 +266,12 @@ func (z *zedrouter) checkAndRecreateAppNetworks(niID uuid.UUID) {
 		}
 		if !appNetStatus.HasError() && !appNetStatus.AwaitNetworkInstance &&
 			appNetConfig.Activate && !appNetStatus.Activated {
-			z.doActivateAppNetwork(*appNetConfig, &appNetStatus)
+			// Re-execute the entire pubsub handler to repeat the full validation process.
+			// The conditions might have changed while the application was waiting for the
+			// network instance to appear or get fixed. For instance, another application
+			// with conflicting port forwarding rules could have been deployed during this
+			// time, which would necessitate preventing the activation of this app's network.
+			z.handleAppNetworkCreate(nil, appNetConfig.Key(), *appNetConfig)
 		}
 		z.log.Functionf("checkAndRecreateAppNetworks(%v) done for %s",
 			niID, appNetConfig.DisplayName)