Update confirm_access to handle failure in constructor

Refactor error handling in failed_net_message

Author: jaladh-singhal

firefly_client/env.py

@@ -93,12 +93,20 @@ def find_default_firefly_html(cls): return cls.firefly_html
 
     @classmethod
     def failed_net_message(cls, location, status_code=-1):
-        s_str = 'with status: %s' % status_code if (status_code > -1) else ''
-        check = 'You may want to check the URL with your web browser.\n'
-        err_message = 'Connection fail to URL %s %s\n%s' % (location, s_str, check)
-        if cls.firefly_lab_extension and cls.firefly_url_lab:
-            err_message += ('\nCheck the Firefly URL in ~/.jupyter/jupyter_notebook_config.py' +
-                            ' or ~/.jupyter/jupyter_notebook_config.json')
-        elif cls.firefly_url:
-            err_message += 'Check setting of FIREFLY_URL environment variable: %s' % cls.firefly_url
+        status_str = f'with status: {status_code}' if status_code > -1 else ''
+        check_msg = 'You may want to check the URL with your web browser.\n'
+        err_message = f'Connection failed to URL {location} {status_str}\n{check_msg}'
+        
+        # url sources in order of precedence
+        url_sources = []
+        if cls.firefly_url: # any environment
+            url_sources.append(f'environment variable "{ENV_FF_URL}"')
+        if cls.firefly_lab_extension and cls.firefly_url_lab: # lab environment
+            url_sources += [
+                '~/.jupyter/jupyter_notebook_config.json',
+                '~/.jupyter/jupyter_notebook_config.py',
+            ]
+        err_message += (f'\nCheck if the Firefly URL is correct, which is '
+                        f'passed as a parameter, or is set via {" or ".join(url_sources)}.')
+
         return err_message

firefly_client/firefly_client.py

@@ -232,17 +232,34 @@ def __init__(self, url, channel, html_file=_def_html_file, token=None, viewer_ov
         self.auth_headers = {'Authorization': 'Bearer {}'.format(token)} if token and ssl else None
         self.header_from_ws = {'FF-channel': channel}
         self.lab_env_tab_type = UNKNOWN
+
         # urls for cmd service and browser
         protocol = 'https' if ssl else 'http'
         self.url_cmd_service = urljoin('{}://{}/'.format(protocol, self.location), 'sticky/CmdSrv')
         self.url_browser = urljoin(urljoin('{}://{}/'.format(protocol, self.location), html_file), '?__wsch=')
         self.url_bw = self.url_browser  # keep around for backward compatibility
+
         self.session = requests.Session()
         token and ssl and self.session.headers.update(self.auth_headers)
         not ssl and token and warn('token ignored: should be None when url starts with http://')
         self.firefly_viewer = FireflyClient.get_viewer_mode(html_file,viewer_override)
-        FireflyClient.confirm_access(url, token)
-        debug('new instance: %s' % url)
+
+        access = FireflyClient.confirm_access(url, token)
+        if not access['success']:
+            debug(f'Failed to access url: {url}, with token: {token}\n'
+                  f'Response status: {access["response"].status_code} ({access["response"].reason})\n'
+                  f'Response headers: {dict_to_str(access["response"].headers)}\n'
+                  f'Response text: {access["response"].text}')
+            url_err_msg = Env.failed_net_message(url, access['response'].status_code)
+            token_err_msg = (
+                'Check if the passed `token` is valid and has the necessary '
+                'authorization to access the above URL.'
+                if token else
+                'If an authorization token is required to access the above URL, '
+                'the `token` parameter must be passed.'
+            )
+            raise ValueError(f'{url_err_msg}\n\n{token_err_msg}')
+        debug(f'new instance: {url}')
 
     def _lab_env_tab_start(self, tab_type, html_file):
         """start a tab in the lab environment, tab_type must be 'lab' or 'browser' """
@@ -276,17 +293,12 @@ def get_viewer_mode(html_file, viewer_override):
             return FireflyClient.SLATE_VIEWER if html_file == 'slate.html' else FireflyClient.TRIVIEW_VIEWER
 
     @staticmethod
-    def confirm_access(url, token):
+    def confirm_access(url, token=None):
         headers = {'Authorization': f'Bearer {token}'} if token else None
         healthz_url = url + ('healthz' if url.endswith('/') else '/healthz')
+        # disable redirects that may happen in the absence of a token
         response = requests.get(healthz_url, headers=headers, allow_redirects=False)
-        if response.status_code == 200:
-            return True
-        else:
-            raise ValueError(
-                f"Access to {url} failed with status code {response.status_code}.\n"
-                f"GET Headers: {response.headers}"
-            )
+        return {'success': response.status_code == 200, 'response': response}
 
     def _send_url_as_get(self, url):
         return self.call_response(self.session.get(url, headers=self.header_from_ws))