Exit when invalid cmd options are set

Exit with an error when both --volume-attach-limit and
--reserved-volume-attachments are specified on the command line.

cmd/options.go

@@ -125,6 +125,14 @@ func GetOptions(fs *flag.FlagSet) *Options {
 		klog.ErrorS(err, "failed to validate and apply logging configuration")
 	}
 
+	if mode != driver.ControllerMode {
+		// nodeOptions must have been populated from the cmdline, validate them.
+		if err := nodeOptions.Validate(); err != nil {
+			klog.Error(err.Error())
+			klog.FlushAndExit(klog.ExitFlushTimeout, 1)
+		}
+	}
+
 	if *version {
 		versionInfo, err := driver.GetVersionJSON()
 		if err != nil {

cmd/options/node_options.go

@@ -17,6 +17,8 @@ limitations under the License.
 package options
 
 import (
+	"fmt"
+
 	flag "github.com/spf13/pflag"
 )
 
@@ -44,3 +46,10 @@ func (o *NodeOptions) AddFlags(fs *flag.FlagSet) {
 	fs.Int64Var(&o.VolumeAttachLimit, "volume-attach-limit", -1, "Value for the maximum number of volumes attachable per node. If specified, the limit applies to all nodes and overrides --reserved-volume-attachments. If not specified, the value is approximated from the instance type.")
 	fs.IntVar(&o.ReservedVolumeAttachments, "reserved-volume-attachments", -1, "Number of volume attachments reserved for system use. Not used when --volume-attach-limit is specified. The total amount of volume attachments for a node is computed as: <nr. of attachments for corresponding instance type> - <number of NICs, if relevant to the instance type> - <reserved-volume-attachments value>. When -1, the amount of reserved attachments is loaded from instance metadata that captured state at node boot and may include not only system disks but also CSI volumes.")
 }
+
+func (o *NodeOptions) Validate() error {
+	if o.VolumeAttachLimit != -1 && o.ReservedVolumeAttachments != -1 {
+		return fmt.Errorf("only one of --volume-attach-limit and --reserved-volume-attachments may be specified")
+	}
+	return nil
+}

cmd/options/node_options_test.go

@@ -55,3 +55,56 @@ func TestNodeOptions(t *testing.T) {
 		})
 	}
 }
+
+func TestValidate(t *testing.T) {
+	testCases := []struct {
+		name        string
+		options     *NodeOptions
+		expectError bool
+	}{
+		{
+			name: "valid VolumeAttachLimit",
+			options: &NodeOptions{
+				VolumeAttachLimit:         42,
+				ReservedVolumeAttachments: -1,
+			},
+			expectError: false,
+		},
+		{
+			name: "valid ReservedVolumeAttachments",
+			options: &NodeOptions{
+				VolumeAttachLimit:         -1,
+				ReservedVolumeAttachments: 42,
+			},
+			expectError: false,
+		},
+		{
+			name: "default options",
+			options: &NodeOptions{
+				VolumeAttachLimit:         -1,
+				ReservedVolumeAttachments: -1,
+			},
+			expectError: false,
+		},
+		{
+			name: "both options set",
+			options: &NodeOptions{
+				VolumeAttachLimit:         1,
+				ReservedVolumeAttachments: 1,
+			},
+			expectError: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := tc.options.Validate()
+			if tc.expectError && err == nil {
+				t.Errorf("Expected error, got nil")
+			}
+			if !tc.expectError && err != nil {
+				t.Errorf("Unexpected error: %v", err)
+			}
+		})
+	}
+}

cmd/options_test.go

@@ -23,6 +23,7 @@ import (
 	"testing"
 
 	flag "github.com/spf13/pflag"
+	"k8s.io/klog/v2"
 
 	"github.com/kubernetes-sigs/aws-ebs-csi-driver/pkg/driver"
 )
@@ -221,6 +222,39 @@ func TestGetOptions(t *testing.T) {
 				}
 			},
 		},
+		{
+			name: "both volume-attach-limit and reserved-volume-attachments specified",
+			testFunc: func(t *testing.T) {
+				oldOSExit := klog.OsExit
+				defer func() { klog.OsExit = oldOSExit }()
+
+				var exitCode int
+				calledExit := false
+				testExit := func(code int) {
+					exitCode = code
+					calledExit = true
+				}
+				klog.OsExit = testExit
+
+				oldArgs := os.Args
+				defer func() { os.Args = oldArgs }()
+				os.Args = []string{
+					"aws-ebs-csi-driver",
+					"--volume-attach-limit=10",
+					"--reserved-volume-attachments=10",
+				}
+
+				flagSet := flag.NewFlagSet("test-flagset", flag.ContinueOnError)
+				_ = GetOptions(flagSet)
+
+				if exitCode != 1 {
+					t.Fatalf("expected exit code 1 but got %d", exitCode)
+				}
+				if !calledExit {
+					t.Fatalf("expect osExit to be called, but wasn't")
+				}
+			},
+		},
 	}
 
 	for _, tc := range testCases {