add cassandra data dir existence tet before backup or restore, fixes #7

pkg/cain/cain.go

@@ -42,6 +42,11 @@ func Backup(o BackupOptions) (string, error) {
 		return "", err
 	}
 
+	log.Println("Testing existence of data dir")
+	if err := utils.TestK8sDirectory(k8sClient, pods, o.Namespace, o.Container, o.CassandraDataDir); err != nil {
+		return "", err
+	}
+
 	log.Println("Backing up schema")
 	dstBasePath, err := BackupKeyspaceSchema(k8sClient, dstClient, o.Namespace, pods[0], o.Container, o.Keyspace, dstPrefix, dstPath)
 	if err != nil {
@@ -101,6 +106,11 @@ func Restore(o RestoreOptions) error {
 		return err
 	}
 
+	log.Println("Testing existence of data dir")
+	if err := utils.TestK8sDirectory(k8sClient, existingPods, o.Namespace, o.Container, o.CassandraDataDir); err != nil {
+		return err
+	}
+
 	log.Println("Getting current schema")
 	_, sum, err := DescribeKeyspaceSchema(k8sClient, o.Namespace, existingPods[0], o.Container, o.Keyspace)
 	if err != nil {

pkg/utils/path.go

@@ -158,3 +158,19 @@ func ChangeFilesOwnership(iK8sClient interface{}, pods []string, namespace, cont
 	}
 	return nil
 }
+
+// TestK8sDirectory checks if a path exists
+func TestK8sDirectory(iK8sClient interface{}, pods []string, namespace, container, cassandraDataDir string) error {
+	k8sClient := iK8sClient.(*skbn.K8sClient)
+	command := []string{"ls", cassandraDataDir}
+	for _, pod := range pods {
+		stderr, err := skbn.Exec(*k8sClient, namespace, pod, container, command, nil, nil)
+		if len(stderr) != 0 {
+			return fmt.Errorf("STDERR: " + (string)(stderr))
+		}
+		if err != nil {
+			return fmt.Errorf(cassandraDataDir + " does not exist. " + err.Error())
+		}
+	}
+	return nil
+}