[multi-asic][chassis] fix the port index in port_index_map for masic (#…

…3897)

What is the motivation for this PR?
The change done in PR #3643 to use the get_port_map, does not work for multi-ASIC platforms. The existing logic in config_facts gives the same index for ports on different ASICs.

The PR is a fix for this problem. get_port_map will use the port index present in the config_db.

How did you do it?
Change in config_facts to get the port index from config_db if its available. If the index is not present use the exisiting lofic to generate the index

How did you verify/test it?
run the test platform_tests/rest_reload_config.py to verify

Signed-off-by: Arvindsrinivasan Lakshmi Narasimhan <arlakshm@microsoft.com>

ansible/library/config_facts.py

@@ -71,8 +71,16 @@ def create_maps(config):
         port_name_list = config["PORT"].keys()
         port_name_list_sorted = natsorted(port_name_list)
 
-        for idx, val in enumerate(port_name_list_sorted):
-            port_index_map[val] = idx
+        #get the port_index from config_db if available
+        port_index_map = {
+            name: int(v['index'])
+            for name, v in config['PORT'].iteritems()
+            if 'index' in v
+        }
+        if not port_index_map:
+            #if not available generate an index
+            for idx, val in enumerate(port_name_list_sorted):
+                port_index_map[val] = idx
 
         port_name_to_alias_map = { name : v['alias'] if 'alias' in v else '' for name, v in config["PORT"].iteritems()}
 
@@ -136,7 +144,7 @@ def main():
                     cfg_file_path = PERSISTENT_CONFIG_PATH.format("")
             with open(cfg_file_path, "r") as f:
                 config = json.load(f)
-        elif m_args["source"] == "running":    
+        elif m_args["source"] == "running":
             config = get_running_config(module, namespace)
         results = get_facts(config)
         module.exit_json(ansible_facts=results)