fix: try two public urls for maintainer exists lint

conda_smithy/lint_recipe.py

@@ -413,16 +413,44 @@ def _maintainer_exists(maintainer: str) -> bool:
         gh = _cached_gh()
         try:
             gh.get_user(maintainer)
+            is_user = True
         except github.UnknownObjectException:
-            return False
-        return True
+            is_user = False
+
+        # for w/e reason, the user endpoint returns an entry for orgs
+        # however the org endpoint does not return an entry for users
+        # so we have to check both
+        try:
+            gh.get_organization(maintainer)
+            is_org = True
+        except github.UnknownObjectException:
+            is_org = False
     else:
-        return (
-            requests.get(
-                f"https://api.github.com/users/{maintainer}"
-            ).status_code
-            == 200
+        # this API request has no token and so has a restrictive rate limit
+        # return (
+        #     requests.get(
+        #         f"https://api.github.com/users/{maintainer}"
+        #     ).status_code
+        #     == 200
+        # )
+        # so we check two public URLs instead.
+        # 1. github.com/<maintainer>?tab=repositories - this URL works for all users and all orgs
+        # 2. https://github.com/orgs/<maintainer>/teams - this URL only works for
+        #    orgs so we make sure it fails
+        # we do not allow redirects to ensure we get the correct status code
+        # for the specific URL we requested
+        req_profile = requests.get(
+            f"https://github.com/{maintainer}?tab=repositories",
+            allow_redirects=False,
+        )
+        is_user = req_profile.status_code == 200
+        req_org = requests.get(
+            f"https://github.com/orgs/{maintainer}/teams",
+            allow_redirects=False,
         )
+        is_org = req_org.status_code == 200
+
+    return is_user and not is_org
 
 
 @lru_cache(maxsize=1)

news/2171-fix-maintainer_exists.rst

@@ -0,0 +1,24 @@
+**Added:**
+
+* <news item>
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* Fixed a bug in checking in recipe maintainers exist without a GitHub token
+  where the anonymous API would run out of requests. (#2171)
+
+**Security:**
+
+* <news item>

tests/test_lint_recipe.py

@@ -1871,6 +1871,42 @@ def test_maintainer_exists(self):
         expected_message = 'Recipe maintainer "isuruf" does not exist'
         self.assertNotIn(expected_message, lints)
 
+        lints, _ = linter.lintify_meta_yaml(
+            {"extra": {"recipe-maintainers": ["conda-forge"]}},
+            conda_forge=True,
+        )
+        expected_message = 'Recipe maintainer "conda-forge" does not exist'
+        self.assertIn(expected_message, lints)
+
+    def test_maintainer_exists_no_token(self):
+        gh_token = os.environ.get("GH_TOKEN", None)
+        try:
+            if "GH_TOKEN" in os.environ:
+                del os.environ["GH_TOKEN"]
+
+            lints, _ = linter.lintify_meta_yaml(
+                {"extra": {"recipe-maintainers": ["support"]}},
+                conda_forge=True,
+            )
+            expected_message = 'Recipe maintainer "support" does not exist'
+            self.assertIn(expected_message, lints)
+
+            lints, _ = linter.lintify_meta_yaml(
+                {"extra": {"recipe-maintainers": ["isuruf"]}}, conda_forge=True
+            )
+            expected_message = 'Recipe maintainer "isuruf" does not exist'
+            self.assertNotIn(expected_message, lints)
+
+            lints, _ = linter.lintify_meta_yaml(
+                {"extra": {"recipe-maintainers": ["conda-forge"]}},
+                conda_forge=True,
+            )
+            expected_message = 'Recipe maintainer "conda-forge" does not exist'
+            self.assertIn(expected_message, lints)
+        finally:
+            if gh_token is not None:
+                os.environ["GH_TOKEN"] = gh_token
+
     def test_maintainer_team_exists(self):
         lints, _ = linter.lintify_meta_yaml(
             {