Show error message when start experiment failed (#996)

Fix issue #890

tools/nni_cmd/launcher.py

@@ -325,12 +325,12 @@ def set_experiment(experiment_config, mode, port, config_file_name):
         request_data['clusterMetaData'].append(
             {'key': 'trial_config', 'value': experiment_config['trial']})
 
-    response = rest_post(experiment_url(port), json.dumps(request_data), REST_TIME_OUT)
+    response = rest_post(experiment_url(port), json.dumps(request_data), REST_TIME_OUT, show_error=True)
     if check_response(response):
         return response
     else:
         _, stderr_full_path = get_log_path(config_file_name)
-        if response:
+        if response is not None:
             with open(stderr_full_path, 'a+') as fout:
                 fout.write(json.dumps(json.loads(response.text), indent=4, sort_keys=True, separators=(',', ':')))
             print_error('Setting experiment error, error message is {}'.format(response.text))

tools/nni_cmd/rest_utils.py

@@ -23,39 +23,48 @@ import time
 import requests
 from .url_utils import check_status_url
 from .constants import REST_TIME_OUT
+from .common_utils import print_error
 
-def rest_put(url, data, timeout):
+def rest_put(url, data, timeout, show_error=False):
     '''Call rest put method'''
     try:
         response = requests.put(url, headers={'Accept': 'application/json', 'Content-Type': 'application/json'},\
                                 data=data, timeout=timeout)
         return response
-    except Exception:
+    except Exception as exception:
+        if show_error:
+            print_error(exception)
         return None
 
-def rest_post(url, data, timeout):
+def rest_post(url, data, timeout, show_error=False):
     '''Call rest post method'''
     try:
         response = requests.post(url, headers={'Accept': 'application/json', 'Content-Type': 'application/json'},\
                                  data=data, timeout=timeout)
         return response
-    except Exception:
+    except Exception as exception:
+        if show_error:
+            print_error(exception)
         return None
 
-def rest_get(url, timeout):
+def rest_get(url, timeout, show_error=False):
     '''Call rest get method'''
     try:
         response = requests.get(url, timeout=timeout)
         return response
-    except Exception:
+    except Exception as exception:
+        if show_error:
+            print_error(exception)
         return None
 
-def rest_delete(url, timeout):
+def rest_delete(url, timeout, show_error=False):
     '''Call rest delete method'''
     try:
         response = requests.delete(url, timeout=timeout)
         return response
-    except Exception:
+    except Exception as exception:
+        if show_error:
+            print_error(exception)
         return None
 
 def check_rest_server(rest_port):