tools: Suppress errors for github.com links.

I have suppressed errors for github.com by adding an function to
exclude domains as well as urls; this is necessary because GitHub has
marked this tool's User-Agent as a blocker crawler.

I have also suppressed reoccurring url errors that do definitely exist.

Fixes #17928.

tools/documentation_crawler/documentation_crawler/spiders/common/spiders.py

@@ -2,6 +2,7 @@ import json
 import os
 import re
 from typing import Callable, Iterator, List, Optional, Union
+from urllib.parse import urlparse
 
 import scrapy
 from scrapy.http import Request, Response
@@ -11,6 +12,15 @@ from scrapy.spidermiddlewares.httperror import HttpError
 from scrapy.utils.url import url_has_any_extension
 from twisted.python.failure import Failure
 
+EXCLUDED_DOMAINS = [
+    # Returns 429 Rate-Limited Errors
+    "github.com",
+    "gist.github.com",
+    # Returns 503 Errors
+    "www.amazon.com",
+    "gitlab.com",
+]
+
 EXCLUDED_URLS = [
     # Google calendar returns 404s on HEAD requests unconditionally
     "https://calendar.google.com/calendar/embed?src=ktiduof4eoh47lmgcl2qunnc0o@group.calendar.google.com",
@@ -19,6 +29,8 @@ EXCLUDED_URLS = [
     # Returns 404 to HEAD requests unconditionally
     "https://www.git-tower.com/blog/command-line-cheat-sheet/",
     "https://marketplace.visualstudio.com/items?itemName=rafaelmaiolla.remote-vscode",
+    "https://www.transifex.com/zulip/zulip/announcements/",
+    "https://marketplace.visualstudio.com/items?itemName=ms-vscode-remote.remote-ssh",
     # Requires authentication
     "https://circleci.com/gh/zulip/zulip/tree/master",
     "https://circleci.com/gh/zulip/zulip/16617",
@@ -164,6 +176,10 @@ class BaseDocumentationSpider(scrapy.Spider):
             callback = self.check_fragment
         if getattr(self, "skip_external", False) and self._is_external_link(url):
             return
+        if urlparse(url).netloc in EXCLUDED_DOMAINS:
+            return
+        if url in EXCLUDED_URLS:
+            return
         yield Request(
             url,
             method=method,
@@ -204,13 +220,12 @@ class BaseDocumentationSpider(scrapy.Spider):
         request.dont_filter = True
         yield request
 
-    def exclude_error(self, url: str) -> bool:
-        return url in EXCLUDED_URLS
-
     def error_callback(self, failure: Failure) -> Optional[Union[Failure, Iterator[Request]]]:
         if isinstance(failure.value, HttpError):
             response = failure.value.response
-            if self.exclude_error(response.url):
+            # Hack: The filtering above does not catch this URL,
+            # likely due to a redirect.
+            if urlparse(response.url).netloc == "idmsa.apple.com":
                 return None
             if response.status == 405 and response.request.method == "HEAD":
                 # Method 'HEAD' not allowed, repeat request with 'GET'