[YANG] add peer switch model (#11828)

Why I did it
Address issue #10966

sign-off: Jing Zhang zhangjing@microsoft.com

How I did it
Add sonic-peer-switch.yang and unit tests.

How to verify it
Compile Compile target/python-wheels/sonic_yang_mgmt-1.0-py3-none-any.whl and target/python-wheels/sonic_yang_models-1.0-py3-none-any.whl.

Which release branch to backport (provide reason below if selected)
 201811
 201911
 202006
 202012
 202106
 202111
 202205
Description for the changelog
Link to config_db schema for YANG module changes
b721ff87b9/src/sonic-yang-models/doc/Configuration.md (peer-switch)

src/sonic-yang-models/doc/Configuration.md

@@ -36,6 +36,7 @@ Table of Contents
          * [MAP_PFC_PRIORITY_TO_QUEUE](#map_pfc_priority_to_queue)  
          * [NTP Global Configuration](#ntp-global-configuration)  
          * [NTP and SYSLOG servers](#ntp-and-syslog-servers)  
+         * [Peer Switch](#peer-switch)
          * [Policer](#policer)   
          * [Port](#port)   
          * [Port Channel](#port-channel)  
@@ -1160,6 +1161,19 @@ attributes in those objects.
 }
 ```
 
+### Peer Switch
+
+Below is an exmaple of the peer switch table configuration. 
+```
+{
+    "PEER_SWITCH": {
+        "vlab-05": {
+            "address_ipv4":  "10.1.0.33"
+        }
+    }
+}
+```
+
 ### Policer
 
 Below is an example of the policer table configuration.

src/sonic-yang-models/setup.py

@@ -152,6 +152,7 @@ setup(
                          './yang-models/sonic-storm-control.yang',
                          './yang-models/sonic-tc-priority-group-map.yang',
                          './yang-models/sonic-tc-queue-map.yang',
+                         './yang-models/sonic-peer-switch.yang',
                          './yang-models/sonic-pfc-priority-queue-map.yang',
                          './yang-models/sonic-pfc-priority-priority-group-map.yang',
                          './yang-models/sonic-port-qos-map.yang',

src/sonic-yang-models/tests/files/sample_config_db.json

@@ -1798,6 +1798,11 @@
             }
         },
 
+        "PEER_SWITCH": {
+            "vlab-05": {
+                "address_ipv4":  "10.1.0.33"
+            }
+        },
 
         "POLICER": {
             "everflow_static_policer": {

src/sonic-yang-models/tests/yang_model_tests/tests/peer-switch.json

@@ -0,0 +1,13 @@
+{
+    "PEER_SWITCH_LOAD_NORMAL": {
+        "desc": "Load PEER_SWITCH for dualtor device."
+    },
+    "PEER_SWITCH_MISSING_DEVICE__NAME": {
+        "desc": "Load PEER_SWITCH missing PEER Device name.",
+        "eStrKey": "Mandatory"
+    },
+    "PEER_SWITCH_INVALID_IP_ADDRESS": {
+        "desc": "Load PEER_SWITCH with invalid IPv4 Address.",
+        "eStrKey": "Pattern"
+    }
+}

src/sonic-yang-models/tests/yang_model_tests/tests_config/peer-switch.json

@@ -0,0 +1,39 @@
+{
+    "PEER_SWITCH_LOAD_NORMAL": {
+        "sonic-peer-switch:sonic-peer-switch": {
+            "sonic-peer-switch:PEER_SWITCH": {
+                "PEER_SWITCH_LIST": [
+                    {
+                        "peer_switch": "vlab-05",
+                        "address_ipv4":  "10.1.0.33"
+                    }
+                ]
+            }
+        }
+    },
+
+    "PEER_SWITCH_MISSING_DEVICE__NAME": {
+        "sonic-peer-switch:sonic-peer-switch": {
+            "sonic-peer-switch:PEER_SWITCH": {
+                "PEER_SWITCH_LIST": [
+                    {
+                        "address_ipv4":  "10.1.0.33"
+                    }
+                ]
+            }
+        }
+    },
+
+    "PEER_SWITCH_INVALID_IP_ADDRESS": {
+        "sonic-peer-switch:sonic-peer-switch": {
+            "sonic-peer-switch:PEER_SWITCH": {
+                "PEER_SWITCH_LIST": [
+                    {
+                        "peer_switch": "vlab-05",
+                        "address_ipv4":  "10.1.0.33/32"
+                    }
+                ]
+            }
+        }
+    }
+}

src/sonic-yang-models/yang-models/sonic-peer-switch.yang

@@ -0,0 +1,49 @@
+module sonic-peer-switch {
+    yang-version 1.1;
+    namespace "http://github.com/Azure/sonic-peer-switch";
+    prefix peer_switch;
+
+    import ietf-inet-types {
+        prefix inet;
+    }
+    
+    import sonic-types {
+        prefix stypes;
+    }
+
+    organization
+        "SONiC";
+
+    contact
+        "SONiC";
+
+    description
+        "SONiC DualToR peer switch data";
+
+    revision 2022-08-23 {
+        description
+            "Initial revision";
+    }
+
+    container sonic-peer-switch {
+        container PEER_SWITCH {
+            list PEER_SWITCH_LIST {
+                max-elements 1;
+
+                key "peer_switch";
+                
+                leaf peer_switch {
+                    type stypes:hostname;
+
+                    description "SONiC DualToR peer host name.";
+                }
+
+                leaf address_ipv4 {
+                    type inet:ipv4-address;
+
+                    description "SONiC DualToR peer's IPv4 address.";
+                }
+            }
+        }
+    }
+}