ceph: do not fail prepareOSD job if devices are not passed

If devices are not specified for node return empty desired devices
list and do not fail prepareOSD job.

Closes: #8097
Signed-off-by: Denis Egorenko <degorenko@mirantis.com>

cmd/rook/ceph/osd.go

@@ -290,6 +290,10 @@ func getLocation(clientset kubernetes.Interface) (string, string, error) {
 
 // Parse the devices, which are sent as a JSON-marshalled list of device IDs with a StorageConfig spec
 func parseDevices(devices string) ([]osddaemon.DesiredDevice, error) {
+	if devices == "" {
+		return []osddaemon.DesiredDevice{}, nil
+	}
+
 	configuredDevices := []osdcfg.ConfiguredDevice{}
 	err := json.Unmarshal([]byte(devices), &configuredDevices)
 	if err != nil {

cmd/rook/ceph/osd_test.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"testing"
 
+	osddaemon "github.com/rook/rook/pkg/daemon/ceph/osd"
 	osdcfg "github.com/rook/rook/pkg/operator/ceph/cluster/osd/config"
 	"github.com/stretchr/testify/assert"
 )
@@ -167,4 +168,8 @@ func TestParseDesiredDevices(t *testing.T) {
 	assert.False(t, result[2].IsDevicePathFilter)
 	assert.False(t, result[3].IsDevicePathFilter)
 
+	// check empty devices list
+	result, err = parseDevices("")
+	assert.NoError(t, err)
+	assert.Equal(t, []osddaemon.DesiredDevice{}, result)
 }