Support VM usage for qemu

Ref https://github.com/GNS3/gns3-gui/issues/829

gns3server/modules/base_vm.py

@@ -48,6 +48,7 @@ class BaseVM:
     def __init__(self, name, vm_id, project, manager, console=None, console_type="telnet"):
 
         self._name = name
+        self._usage = ""
         self._id = vm_id
         self._project = project
         self._manager = manager
@@ -124,6 +125,26 @@ class BaseVM:
                                                                         new_name=new_name))
         self._name = new_name
 
+    @property
+    def usage(self):
+        """
+        Returns the usage for this VM.
+
+        :returns: usage
+        """
+
+        return self._usage
+
+    @usage.setter
+    def usage(self, new_usage):
+        """
+        Sets the usage of this VM.
+
+        :param new_usage: usage
+        """
+
+        self._usage = new_usage
+
     @property
     def id(self):
         """

gns3server/schemas/qemu.py

@@ -38,6 +38,10 @@ QEMU_CREATE_SCHEMA = {
             "type": "string",
             "minLength": 1,
         },
+        "usage": {
+            "description": "How to use the qemu VM",
+            "type": "string",
+        },
         "linked_clone": {
             "description": "either the VM is a linked clone or not",
             "type": "boolean"
@@ -211,6 +215,10 @@ QEMU_UPDATE_SCHEMA = {
             "type": ["string", "null"],
             "minLength": 1,
         },
+        "usage": {
+            "description": "How to use the qemu VM",
+            "type": "string",
+        },
         "qemu_path": {
             "description": "Path to QEMU",
             "type": ["string", "null"],
@@ -389,6 +397,10 @@ QEMU_OBJECT_SCHEMA = {
             "type": "string",
             "minLength": 1,
         },
+        "usage": {
+            "description": "How to use the qemu VM",
+            "type": "string",
+        },
         "qemu_path": {
             "description": "path to QEMU",
             "type": "string",
@@ -548,12 +560,45 @@ QEMU_OBJECT_SCHEMA = {
         },
     },
     "additionalProperties": False,
-    "required": ["vm_id", "project_id", "name", "qemu_path", "platform", "console_type", "hda_disk_image", "hdb_disk_image",
-                 "hdc_disk_image", "hdd_disk_image", "hda_disk_image_md5sum", "hdb_disk_image_md5sum",
-                 "hdc_disk_image_md5sum", "hdd_disk_image_md5sum", "hda_disk_interface", "hdb_disk_interface", "hdc_disk_interface",
-                 "hdd_disk_interface", "cdrom_image", "cdrom_image_md5sum", "boot_priority", "ram", "cpus", "adapters", "adapter_type",
-                 "mac_address", "console", "initrd", "kernel_image", "initrd_md5sum", "kernel_image_md5sum", "kernel_command_line",
-                 "legacy_networking", "acpi_shutdown", "cpu_throttling", "process_priority", "options", "vm_directory"]
+    "required": ["vm_id",
+                 "project_id",
+                 "name",
+                 "usage",
+                 "qemu_path",
+                 "platform",
+                 "console_type",
+                 "hda_disk_image",
+                 "hdb_disk_image",
+                 "hdc_disk_image",
+                 "hdd_disk_image",
+                 "hda_disk_image_md5sum",
+                 "hdb_disk_image_md5sum",
+                 "hdc_disk_image_md5sum",
+                 "hdd_disk_image_md5sum",
+                 "hda_disk_interface",
+                 "hdb_disk_interface",
+                 "hdc_disk_interface",
+                 "hdd_disk_interface",
+                 "cdrom_image",
+                 "cdrom_image_md5sum",
+                 "boot_priority",
+                 "ram",
+                 "cpus",
+                 "adapters",
+                 "adapter_type",
+                 "mac_address",
+                 "console",
+                 "initrd",
+                 "kernel_image",
+                 "initrd_md5sum",
+                 "kernel_image_md5sum",
+                 "kernel_command_line",
+                 "legacy_networking",
+                 "acpi_shutdown",
+                 "cpu_throttling",
+                 "process_priority",
+                 "options",
+                 "vm_directory"]
 }
 
 QEMU_BINARY_LIST_SCHEMA = {