cleanup: allow ability to add cleanup functions from daemon

Only add the cleanup function to cleanup endpoint-related information when
running in tandem with Flannel once the daemon's endpointManager field is
initialized.

Signed-off by: Ian Vernon <ian@cilium.io>

daemon/cleanup.go

@@ -20,8 +20,7 @@ import (
 	"sync"
 	"syscall"
 
-	"github.com/cilium/cilium/pkg/endpointmanager"
-	"github.com/cilium/cilium/pkg/option"
+	"github.com/cilium/cilium/pkg/lock"
 	"github.com/cilium/cilium/pkg/pidfile"
 )
 
@@ -31,8 +30,31 @@ var (
 	cleanUPSig = make(chan struct{})
 	// cleanUPWg all cleanup operations will be marked as Done() when completed.
 	cleanUPWg = &sync.WaitGroup{}
+
+	cleanupFuncs = &cleanupFuncList{
+		funcs: make([]func(), 0),
+	}
 )
 
+type cleanupFuncList struct {
+	funcs []func()
+	lock  lock.Mutex
+}
+
+func (c *cleanupFuncList) Add(newFunc func()) {
+	c.lock.Lock()
+	c.funcs = append(c.funcs, newFunc)
+	c.lock.Unlock()
+}
+
+func (c *cleanupFuncList) Run() {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	for k := range c.funcs {
+		c.funcs[k]()
+	}
+}
+
 func registerSigHandler() <-chan struct{} {
 	sig := make(chan os.Signal, 1)
 	signal.Notify(sig, syscall.SIGQUIT, syscall.SIGINT, syscall.SIGHUP, syscall.SIGTERM)
@@ -42,11 +64,7 @@ func registerSigHandler() <-chan struct{} {
 			log.WithField("signal", s).Info("Exiting due to signal")
 			pidfile.Clean()
 			Clean()
-			if option.Config.FlannelUninstallOnExit {
-				for _, ep := range endpointmanager.GetEndpoints() {
-					ep.DeleteBPFProgramLocked()
-				}
-			}
+			cleanupFuncs.Run()
 			break
 		}
 		close(interrupt)

daemon/daemon.go

@@ -744,6 +744,17 @@ func NewDaemon(dp datapath.Datapath, iptablesManager rulesManager) (*Daemon, *en
 	// Must be done before calling policy.NewPolicyRepository() below.
 	identity.InitWellKnownIdentities()
 
+	epMgr := endpointmanager.NewEndpointManager(&endpointsynchronizer.EndpointSynchronizer{})
+
+	// Cleanup flannel on exit
+	cleanupFuncs.Add(func() {
+		if option.Config.FlannelUninstallOnExit {
+			for _, ep := range epMgr.GetEndpoints() {
+				ep.DeleteBPFProgramLocked()
+			}
+		}
+	})
+
 	d := Daemon{
 		loadBalancer:      loadbalancer.NewLoadBalancer(),
 		k8sSvcCache:       k8s.NewServiceCache(),
@@ -758,7 +769,7 @@ func NewDaemon(dp datapath.Datapath, iptablesManager rulesManager) (*Daemon, *en
 		datapath:          dp,
 		nodeDiscovery:     nodediscovery.NewNodeDiscovery(nodeMngr, mtuConfig),
 		iptablesManager:   iptablesManager,
-		endpointManager:   endpointmanager.NewEndpointManager(&endpointsynchronizer.EndpointSynchronizer{}),
+		endpointManager:   epMgr,
 	}
 
 	endpointmanager.GlobalEndpointManager = endpointmanager.NewEndpointManager(&endpointsynchronizer.EndpointSynchronizer{})