vpp: recover from panic in vpp manager

Previously, any return from the VPP manager was treated as an indication
that VPP had exited or crashed, triggering configuration restoration.

However, if the VPP manager itself panicked while VPP was still running,
the deferred logic would interpret this as a VPP crash and attempt to
restore the configuration. Since VPP was actually still alive, the
restoration could hang and the original panic would never be properly
surfaced.

This change adds panic recovery in the VPP manager to prevent false
assumptions about VPP state and avoid blocking during restore when the
failure originates in the manager itself.

When VPPmanager crashes we kill VPP, wait a bit, then restore the config.

Author: hedibouattour

vpp-manager/vpp_runner.go

@@ -945,10 +945,23 @@ func (v *VppRunner) runVpp() (err error) {
 		vppProcess = vppCmd.Process
 	}
 
-	/**
-	 * From this point it is very important that every exit
-	 * path calls restoreConfiguration after vpp exits */
-	defer v.restoreConfiguration(v.allInterfacesPhysical())
+	defer func() {
+		if r := recover(); r != nil {
+			// we recover and log the error if there is a bug in vpp-manager
+			fmt.Println("Recovered. Error:\n", r)
+			// then we kill vpp and restore configuration
+			terminateVpp("Killing VPP, error in vpp-manager : %v", r)
+			// we need to wait a bit to make sure VPP is dead before restoring config
+			time.Sleep(time.Second * 5)
+			v.restoreConfiguration(v.allInterfacesPhysical())
+		} else {
+			/**
+			 * From this point it is very important that every exit
+			 * path calls restoreConfiguration if vpp exits
+			 * this is called when vppDeadChan is triggered */
+			v.restoreConfiguration(v.allInterfacesPhysical())
+		}
+	}()
 
 	log.Infof("VPP started [PID %d]", vppProcess.Pid)
 	runningCond.Broadcast()