Add other common functions

Author: jsafrane

connection/connection.go

@@ -24,6 +24,9 @@ import (
 	"strings"
 	"time"
 
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
 	"github.com/container-storage-interface/spec/lib/go/csi"
 	"github.com/kubernetes-csi/csi-lib-utils/protosanitizer"
 	"google.golang.org/grpc"
@@ -33,6 +36,9 @@ import (
 const (
 	// Interval of logging connection errors
 	connectionLoggingInterval = 10 * time.Second
+
+	// Interval of trying to call Probe() until it succeeds
+	probeInterval = 1 * time.Second
 )
 
 // Connect opens insecure gRPC connection to a CSI driver. Address must be either absolute path to UNIX domain socket
@@ -163,6 +169,7 @@ func LogGRPC(ctx context.Context, method string, req, reply interface{}, cc *grp
 	return err
 }
 
+// GetDriverName returns name of CSI driver.
 func GetDriverName(ctx context.Context, conn *grpc.ClientConn) (string, error) {
 	client := csi.NewIdentityClient(conn)
 
@@ -177,3 +184,111 @@ func GetDriverName(ctx context.Context, conn *grpc.ClientConn) (string, error) {
 	}
 	return name, nil
 }
+
+// PluginCapabilitySet is set of CSI plugin capabilities. Only supported capabilities are in the map.
+type PluginCapabilitySet map[csi.PluginCapability_Service_Type]bool
+
+// GetPluginCapabilities returns set of supported capabilities of CSI driver.
+func GetPluginCapabilities(ctx context.Context, conn *grpc.ClientConn) (PluginCapabilitySet, error) {
+	client := csi.NewIdentityClient(conn)
+	req := csi.GetPluginCapabilitiesRequest{}
+	rsp, err := client.GetPluginCapabilities(ctx, &req)
+	if err != nil {
+		return nil, err
+	}
+	caps := PluginCapabilitySet{}
+	for _, cap := range rsp.GetCapabilities() {
+		if cap == nil {
+			continue
+		}
+		srv := cap.GetService()
+		if srv == nil {
+			continue
+		}
+		t := srv.GetType()
+		caps[t] = true
+	}
+	return caps, nil
+}
+
+// ControllerCapabilitySet is set of CSI controller capabilities. Only supported capabilities are in the map.
+type ControllerCapabilitySet map[csi.ControllerServiceCapability_RPC_Type]bool
+
+// GetControllerCapabilities returns set of supported controller capabilities of CSI driver.
+func GetControllerCapabilities(ctx context.Context, conn *grpc.ClientConn) (ControllerCapabilitySet, error) {
+	client := csi.NewControllerClient(conn)
+	req := csi.ControllerGetCapabilitiesRequest{}
+	rsp, err := client.ControllerGetCapabilities(ctx, &req)
+	if err != nil {
+		return nil, err
+	}
+
+	caps := ControllerCapabilitySet{}
+	for _, cap := range rsp.GetCapabilities() {
+		if cap == nil {
+			continue
+		}
+		rpc := cap.GetRpc()
+		if rpc == nil {
+			continue
+		}
+		t := rpc.GetType()
+		caps[t] = true
+	}
+	return caps, nil
+}
+
+// ProbeForever calls Probe() of a CSI driver and waits until the driver becomes ready.
+// Any error other than timeout is returned.
+func ProbeForever(conn *grpc.ClientConn, singleProbeTimeout time.Duration) error {
+	for {
+		klog.Info("Probing CSI driver for readiness")
+		ready, err := probeOnce(conn, singleProbeTimeout)
+		if err != nil {
+			st, ok := status.FromError(err)
+			if !ok {
+				// This is not gRPC error. The probe must have failed before gRPC
+				// method was called, otherwise we would get gRPC error.
+				return fmt.Errorf("CSI driver probe failed: %s", err)
+			}
+			if st.Code() != codes.DeadlineExceeded {
+				return fmt.Errorf("CSI driver probe failed: %s", err)
+			}
+			// Timeout -> driver is not ready. Fall through to sleep() below.
+			klog.Warning("CSI driver probe timed out")
+		} else {
+			if ready {
+				return nil
+			}
+			klog.Warning("CSI driver is not ready")
+		}
+		// Timeout was returned or driver is not ready.
+		time.Sleep(probeInterval)
+	}
+}
+
+// probeOnce is a helper to simplify defer cancel()
+func probeOnce(conn *grpc.ClientConn, timeout time.Duration) (bool, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+	return Probe(ctx, conn)
+}
+
+// Probe calls driver Probe() just once and returns its result without any processing.
+func Probe(ctx context.Context, conn *grpc.ClientConn) (ready bool, err error) {
+	client := csi.NewIdentityClient(conn)
+
+	req := csi.ProbeRequest{}
+	rsp, err := client.Probe(ctx, &req)
+
+	if err != nil {
+		return false, err
+	}
+
+	r := rsp.GetReady()
+	if r == nil {
+		// "If not present, the caller SHALL assume that the plugin is in a ready state"
+		return true, nil
+	}
+	return r.GetValue(), nil
+}