[k8s]: Bypass the systemd service restart limit and do immediately re…

…start when change to local mode (#15432)

Why I did it
During the upgrade process via k8s, the feature's systemd service will restart as well, all of the feature systemd service has restart number limit, and the limit number is too small, only three times. if fallback happens when upgrade, the start count will be 2, just once again, the systemd service will be down. So, need to bypass this. This restart function will be called when do local -> kube, kube -> kube, kube ->local, each time call this function, we indeed need to restart successfully, so do reset-failed every time we do restart.
When need to go back to local mode, we do systemd restart immediately without waiting the default restart interval time so that we can reduce the container down time.

Work item tracking
Microsoft ADO (number only):
24172368

How I did it
Before every restart for upgrade, do reset feature's restart number. The restart number will be reset to 0 to bypass the restart limit.
When need to go back to local mode, we do systemd restart immediately.

How to verify it
Feature's systemd service can be always restarted successfully during upgrade process via k8s.

src/sonic-ctrmgrd/ctrmgr/ctrmgrd.py

@@ -151,6 +151,7 @@ def is_systemd_active(feat):
 def restart_systemd_service(server, feat, owner):
     log_debug("Restart service {} to owner:{}".format(feat, owner))
     if not UNIT_TESTING:
+        subprocess.call(["systemctl", "reset-failed", str(feat)])
         status = subprocess.call(["systemctl", "restart", str(feat)])
     else:
         server.mod_db_entry(STATE_DB_NAME,
@@ -551,6 +552,7 @@ def on_state_update(self, key, op, data):
 
         self.st_data[key] = _update_entry(dflt_st_feat, data)
         remote_state = self.st_data[key][ST_FEAT_REMOTE_STATE]
+        current_owner = self.st_data[key][ST_FEAT_OWNER]
 
         if (remote_state == REMOTE_RUNNING) and (old_remote_state != remote_state):
             # Tag latest
@@ -563,6 +565,13 @@ def on_state_update(self, key, op, data):
 
             log_debug("try to tag latest label after {} seconds @{}".format(
                     remote_ctr_config[TAG_IMAGE_LATEST], start_time))
+
+        # This is for going back to local without waiting the systemd restart time
+        # when k8s is down, can't deploy containers to worker and need to go back to local
+        # if current owner is already local, we don't do restart
+        if (current_owner != OWNER_LOCAL) and (remote_state == REMOTE_NONE) and (old_remote_state == REMOTE_STOPPED):
+            restart_systemd_service(self.server, key, OWNER_LOCAL)
+            return
 
         if (not init):
             if (old_remote_state == remote_state):

src/sonic-ctrmgrd/tests/ctrmgrd_test.py

@@ -324,6 +324,37 @@
                 }
             }
         }
+    },
+    4: {
+        common_test.DESCR: "Restart immediately to go back to local when remote_state changes to none from stopped",
+        common_test.ARGS: "ctrmgrd",
+        common_test.PRE: {
+            common_test.STATE_DB_NO: {
+                common_test.FEATURE_TABLE: {
+                    "snmp": {
+                        "remote_state": "stopped",
+                    }
+                }
+            }
+        },
+        common_test.UPD: {
+            common_test.STATE_DB_NO: {
+                common_test.FEATURE_TABLE: {
+                    "snmp": {
+                        "remote_state": "none",
+                    }
+                }
+            }
+        },
+        common_test.POST: {
+            common_test.STATE_DB_NO: {
+                common_test.FEATURE_TABLE: {
+                    "snmp": {
+                        "restart": "true"
+                    }
+                }
+            }
+        }
     }
 }