Implement VM rollback

Closes #184

api-daemon/pvcapid/flaskapi.py

@@ -3202,6 +3202,54 @@ class API_VM_Snapshot(Resource):
 api.add_resource(API_VM_Snapshot, "/vm/<vm>/snapshot")
 
 
+# /vm/<vm>/snapshot/rollback
+class API_VM_Snapshot_Rollback(Resource):
+    @RequestParser(
+        [
+            {
+                "name": "snapshot_name",
+                "required": True,
+                "helptext": "A snapshot name must be specified",
+            },
+        ]
+    )
+    @Authenticator
+    def post(self, vm, reqargs):
+        """
+        Roll back to a snapshot of a VM's disks and configuration
+        ---
+        tags:
+          - vm
+        parameters:
+          - in: query
+            name: snapshot_name
+            type: string
+            required: true
+            description: The name of the snapshot to roll back to
+        responses:
+          200:
+            description: OK
+            schema:
+              type: object
+              id: Message
+          400:
+            description: Execution error
+            schema:
+              type: object
+              id: Message
+          404:
+            description: Not found
+            schema:
+              type: object
+              id: Message
+        """
+        snapshot_name = reqargs.get("snapshot_name", None)
+        return api_helper.rollback_vm_snapshot(vm, snapshot_name)
+
+
+api.add_resource(API_VM_Snapshot_Rollback, "/vm/<vm>/snapshot/rollback")
+
+
 ##########################################################
 # Client API - Network
 ##########################################################

api-daemon/pvcapid/helper.py

@@ -813,6 +813,30 @@ def remove_vm_snapshot(
     return output, retcode
 
 
+@ZKConnection(config)
+def rollback_vm_snapshot(
+    zkhandler,
+    domain,
+    snapshot_name,
+):
+    """
+    Roll back to a snapshot of a VM.
+    """
+    retflag, retdata = pvc_vm.rollback_vm_snapshot(
+        zkhandler,
+        domain,
+        snapshot_name,
+    )
+
+    if retflag:
+        retcode = 200
+    else:
+        retcode = 400
+
+    output = {"message": retdata.replace('"', "'")}
+    return output, retcode
+
+
 @ZKConnection(config)
 def vm_attach_device(zkhandler, vm, device_spec_xml):
     """