rbd: move driver component into the rbd/driver package

The rbd package contains several functions that can be used by
CSI-Addons Service implmentations. Unfortunately it is not possible to
do this, as the rbd-driver needs to import the csi-addons/rbd package to
provide the CSI-Addons server. This causes a circular import when
services use the rbd package:

 - rbd/driver.go import csi-addons/rbd
 - csi-addons/rbd import rbd (including the driver)

By moving rbd/driver.go into its own package, the circular import can be
prevented.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/rbd/driver/driver_test.go

@@ -0,0 +1,51 @@
+/*
+Copyright 2021 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rbddriver
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/ceph/ceph-csi/internal/util"
+)
+
+func TestSetupCSIAddonsServer(t *testing.T) {
+	t.Parallel()
+
+	// endpoint in a temporary directory
+	tmpDir := t.TempDir()
+	endpoint := "unix://" + tmpDir + "/csi-addons.sock"
+
+	config := &util.Config{
+		CSIAddonsEndpoint: endpoint,
+	}
+
+	drv := &Driver{}
+	err := drv.setupCSIAddonsServer(config)
+	require.NoError(t, err)
+	require.NotNil(t, drv.cas)
+
+	// verify the socket file has been created
+	_, err = os.Stat(tmpDir + "/csi-addons.sock")
+	assert.NoError(t, err)
+
+	// stop the gRPC server
+	drv.cas.Stop()
+}