Review feedback: Support other nextstrain.org-like remotes

CHANGES.md

@@ -13,6 +13,12 @@ development source code and as such may not be routinely kept up to date.
 
 # __NEXT__
 
+## Improvements
+
+* Several kinds of errors from `nextstrain login` and `nextstrain whoami`
+  related to their interactions with a remote server are now clearer.
+  ([#347](https://github.com/nextstrain/cli/pull/347))
+
 
 # 8.0.0 (18 January 2024)
 

nextstrain/cli/authn/__init__.py

@@ -100,12 +100,13 @@ def login(origin: Origin, credentials: Optional[Callable[[], Tuple[str, str]]] =
 
 def renew(origin: Origin) -> Optional[User]:
     """
-    Renews existing tokens for *origin*, if possible.
+    Renews existing saved credentials for *origin*, if possible.
 
     Returns a :class:`User` object with renewed information about the logged in
     user when successful.
 
-    Raises a :class:`UserError` if authentication fails.
+    Returns ``None`` if there are no saved credentials or if they're unable to
+    be automatically renewed.
     """
     assert origin
 
@@ -183,9 +184,15 @@ def current_user(origin: Origin) -> Optional[User]:
     """
     assert origin
 
-    session = Session(origin)
     tokens = _load_tokens(origin)
 
+    # Short-circuit if we don't have any tokens to speak of.  Avoids trying to
+    # fetch authn metadata from the remote origin.
+    if all(token is None for token in tokens.values()):
+        return None
+
+    session = Session(origin)
+
     try:
         try:
             session.verify_tokens(**tokens)

nextstrain/cli/authn/configuration.py

@@ -20,18 +20,31 @@ def openid_configuration(origin: Origin):
     assert origin
 
     with requests.Session() as http:
-        response = http.get(origin.rstrip("/") + "/.well-known/openid-configuration")
+        try:
+            response = http.get(origin.rstrip("/") + "/.well-known/openid-configuration")
+            response.raise_for_status()
+            return response.json()
 
-        if response.status_code == 404:
+        except requests.exceptions.ConnectionError as err:
             raise UserError(f"""
-                Failed to retrieve authentication metadata for {origin}.
+                Could not connect to {origin} to retrieve
+                authentication metadata:
+
+                    {type(err).__name__}: {err}
+
+                That remote may be invalid or you may be experiencing network
+                connectivity issues.
+                """) from err
+
+        except (requests.exceptions.HTTPError, requests.exceptions.JSONDecodeError) as err:
+            raise UserError(f"""
+                Failed to retrieve authentication metadata for {origin}:
+
+                    {type(err).__name__}: {err}
 
                 That remote seems unlikely to be an alternate nextstrain.org
                 instance or an internal Nextstrain Groups Server instance.
-                """)
-
-        response.raise_for_status()
-        return response.json()
+                """) from err
 
 
 def client_configuration(origin: Origin):