Merge pull request kubernetes-csi#240 from jsafrane/dont-crash

Don't exit the probe on connection issues

cmd/livenessprobe/main.go

@@ -23,10 +23,8 @@ import (
 	"net"
 	"net/http"
 	"os"
-	"sync"
 	"time"
 
-	"google.golang.org/grpc"
 	"k8s.io/klog/v2"
 
 	"k8s.io/component-base/featuregate"
@@ -62,7 +60,7 @@ func (h *healthProbe) checkProbe(w http.ResponseWriter, req *http.Request) {
 	ctx, cancel := context.WithTimeout(req.Context(), *probeTimeout)
 	defer cancel()
 
-	conn, err := acquireConnection(ctx, h.metricsManager)
+	conn, err := connlib.Connect(*csiAddress, h.metricsManager, connlib.WithTimeout(*probeTimeout))
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
 		w.Write([]byte(err.Error()))
@@ -92,37 +90,6 @@ func (h *healthProbe) checkProbe(w http.ResponseWriter, req *http.Request) {
 	klog.V(5).InfoS("Health check succeeded")
 }
 
-// acquireConnection wraps the connlib.Connect but adding support to context
-// cancelation.
-func acquireConnection(ctx context.Context, metricsManager metrics.CSIMetricsManager) (conn *grpc.ClientConn, err error) {
-
-	var m sync.Mutex
-	var canceled bool
-	ready := make(chan bool)
-	go func() {
-		conn, err = connlib.Connect(*csiAddress, metricsManager)
-
-		m.Lock()
-		defer m.Unlock()
-		if err != nil && canceled && conn != nil {
-			conn.Close()
-		}
-
-		close(ready)
-	}()
-
-	select {
-	case <-ctx.Done():
-		m.Lock()
-		defer m.Unlock()
-		canceled = true
-		return nil, ctx.Err()
-
-	case <-ready:
-		return conn, err
-	}
-}
-
 func main() {
 	fg := featuregate.NewFeatureGate()
 	logsapi.AddFeatureGates(fg)
@@ -151,10 +118,14 @@ func main() {
 	}
 
 	metricsManager := metrics.NewCSIMetricsManager("" /* driverName */)
-	csiConn, err := acquireConnection(context.Background(), metricsManager)
+	// Connect to the CSI driver without any timeout to avoid crashing the probe when the driver is not ready yet.
+	// Goal: liveness probe never crashes, it only fails the probe when the driver is not available (yet).
+	// Since a http server for the probe is not running at this point, Kubernetes liveness probe will fail immediately
+	// with "connection refused", which is good enough to fail the probe.
+	csiConn, err := connlib.Connect(*csiAddress, metricsManager, connlib.WithTimeout(0))
 	if err != nil {
 		// connlib should retry forever so a returned error should mean
-		// the grpc client is misconfigured rather than an error on the network
+		// the grpc client is misconfigured rather than an error on the network or CSI driver.
 		klog.ErrorS(err, "Failed to establish connection to CSI driver")
 		klog.FlushAndExit(klog.ExitFlushTimeout, 1)
 	}
@@ -163,6 +134,7 @@ func main() {
 	csiDriverName, err := rpc.GetDriverName(context.Background(), csiConn)
 	csiConn.Close()
 	if err != nil {
+		// The CSI driver does not support GetDriverName, which is serious enough to crash the probe.
 		klog.ErrorS(err, "Failed to get CSI driver name")
 		klog.FlushAndExit(klog.ExitFlushTimeout, 1)
 	}

go.mod

@@ -7,7 +7,6 @@ require (
 	github.com/golang/mock v1.6.0
 	github.com/kubernetes-csi/csi-lib-utils v0.17.0
 	github.com/kubernetes-csi/csi-test/v5 v5.2.0
-	google.golang.org/grpc v1.60.1
 	k8s.io/component-base v0.29.0
 	k8s.io/klog/v2 v2.110.1
 )
@@ -46,6 +45,7 @@ require (
 	golang.org/x/sys v0.14.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20231106174013-bbf56f31fb17 // indirect
+	google.golang.org/grpc v1.60.1 // indirect
 	google.golang.org/protobuf v1.31.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect