Add Subnets info for user-defined network

* If user doesn't specify the subnets to create a network, it will pick
  subnets from inside preferred pool. This PR aims to inspect these subnets info

* Add integration tests for docker inspect the subnets.

* docker-py project is already synchronized.

* jenkins checks depend on https://github.com/docker/docker-py/pull/888

Fixes issue #18626

Signed-off-by: Wen Cheng Ma <wenchma@cn.ibm.com>
Upstream-commit: 5cc672b0061f3df41073cb7b4ff962998a13a09c
Component: engine

components/engine/docs/reference/api/docker_remote_api.md

@@ -121,6 +121,7 @@ This section lists each version from latest to oldest.  Each listing includes a
   for custom IPAM plugins.
 * `GET /networks/{network-id}` Now returns IPAM config options for custom IPAM plugins if any
   are available.
+* `GET /networks/<network-id>` now returns subnets info for user-defined networks.
 
 ### v1.21 API changes
 

components/engine/docs/reference/api/docker_remote_api_v1.22.md

@@ -2937,7 +2937,7 @@ Status Codes:
 
 **Example request**:
 
-    GET /networks/f2de39df4171b0dc801e8002d1d999b77256983dfc63041c0f34030aa3977566 HTTP/1.1
+    GET /networks/7d86d31b1478e7cca9ebed7e73aa0fdeec46c5ca29497431d3007d2d9e15ed99 HTTP/1.1
 
 **Example response**:
 
@@ -2946,15 +2946,16 @@ HTTP/1.1 200 OK
 Content-Type: application/json
 
 {
-  "Name": "bridge",
-  "Id": "f2de39df4171b0dc801e8002d1d999b77256983dfc63041c0f34030aa3977566",
+  "Name": "net01",
+  "Id": "7d86d31b1478e7cca9ebed7e73aa0fdeec46c5ca29497431d3007d2d9e15ed99",
   "Scope": "local",
   "Driver": "bridge",
   "IPAM": {
     "Driver": "default",
     "Config": [
       {
-        "Subnet": "172.17.0.0/16"
+        "Subnet": "172.19.0.0/16",
+        "Gateway": "172.19.0.1/16"
       }
     ],
     "Options": {
@@ -2962,11 +2963,11 @@ Content-Type: application/json
     }
   },
   "Containers": {
-    "39b69226f9d79f5634485fb236a23b2fe4e96a0a94128390a7fbbcc167065867": {
-      "Name": "mad_mclean",
-      "EndpointID": "ed2419a97c1d9954d05b46e462e7002ea552f216e9b136b80a7db8d98b442eda",
-      "MacAddress": "02:42:ac:11:00:02",
-      "IPv4Address": "172.17.0.2/16",
+    "19a4d5d687db25203351ed79d478946f861258f018fe384f229f2efa4b23513c": {
+      "Name": "test",
+      "EndpointID": "628cadb8bcb92de107b2a1e516cbffe463e321f548feb37697cce00ad694f21a",
+      "MacAddress": "02:42:ac:13:00:02",
+      "IPv4Address": "172.19.0.2/16",
       "IPv6Address": ""
     }
   },

components/engine/docs/reference/commandline/network_inspect.md

@@ -17,7 +17,7 @@ parent = "smn_cli"
       -f, --format=       Format the output using the given go template.
       --help             Print usage
 
-Returns information about one or more networks. By default, this command renders all results in a JSON object. For example, if you connect two containers to a network:
+Returns information about one or more networks. By default, this command renders all results in a JSON object. For example, if you connect two containers to the default `bridge` network:
 
 ```bash
 $ sudo docker run -itd --name=container1 busybox
@@ -78,6 +78,32 @@ $ sudo docker network inspect bridge
 ]
 ```
 
+Returns the information about the user-defined network:
+
+```bash
+$ docker network create simple-network
+69568e6336d8c96bbf57869030919f7c69524f71183b44d80948bd3927c87f6a
+$ docker network inspect simple-network
+[
+    {
+        "Name": "simple-network",
+        "Id": "69568e6336d8c96bbf57869030919f7c69524f71183b44d80948bd3927c87f6a",
+        "Scope": "local",
+        "Driver": "bridge",
+        "IPAM": {
+            "Driver": "default",
+            "Config": [
+                {
+                    "Subnet": "172.22.0.0/16",
+                    "Gateway": "172.22.0.1/16"
+                }
+            ]
+        },
+        "Containers": {},
+        "Options": {}
+    }
+]
+```
 
 ## Related information