Support duplicate for Docker

Ref https://github.com/GNS3/gns3-gui/issues/1065

gns3server/handlers/api/compute/docker_handler.py

@@ -141,6 +141,26 @@ class DockerHandler:
         yield from container.delete()
         response.set_status(204)
 
+    @Route.post(
+        r"/projects/{project_id}/docker/nodes/{node_id}/duplicate",
+        parameters={
+            "project_id": "Project UUID",
+            "node_id": "Node UUID"
+        },
+        status_codes={
+            201: "Instance duplicated",
+            404: "Instance doesn't exist"
+        },
+        description="Duplicate a Docker instance")
+    def duplicate(request, response):
+
+        new_node = yield from Docker.instance().duplicate_node(
+            request.match_info["node_id"],
+            request.json["destination_node_id"]
+        )
+        response.set_status(201)
+        response.json(new_node)
+
     @Route.post(
         r"/projects/{project_id}/docker/nodes/{node_id}/pause",
         parameters={

tests/handlers/api/compute/test_docker.py

@@ -132,8 +132,8 @@ def test_docker_update_nio(http_compute, vm):
                                         "lport": 4242,
                                         "rport": 4343,
                                         "rhost": "127.0.0.1"
-                                    },
-                                    example=True)
+        },
+            example=True)
     assert response.status == 201, response.body.decode()
     assert response.route == "/projects/{project_id}/docker/nodes/{node_id}/adapters/{adapter_number:\d+}/ports/{port_number:\d+}/nio"
 
@@ -184,3 +184,17 @@ def test_docker_stop_capture(http_compute, vm, tmpdir, project):
             assert response.status == 204
 
             assert stop_capture.called
+
+
+def test_docker_duplicate(http_compute, vm):
+    with asyncio_patch("gns3server.compute.docker.Docker.duplicate_node", return_value=True) as mock:
+        response = http_compute.post(
+            "/projects/{project_id}/docker/nodes/{node_id}/duplicate".format(
+                project_id=vm["project_id"],
+                node_id=vm["node_id"]),
+            body={
+                "destination_node_id": str(uuid.uuid4())
+            },
+            example=True)
+        assert mock.called
+        assert response.status == 201