Improve error handling for Zyte API (#123)

Author: Gallaecio

.bandit.yml

@@ -0,0 +1,3 @@
+skips:
+- B101  # assert_used, needed for mypy
+exclude_dirs: ['tests']

.github/workflows/main.yml

@@ -15,9 +15,8 @@ jobs:
         - python-version: "3.4"
           env:
             TOXENV: py34
-        - python-version: "3.5"
-          env:
-            TOXENV: py
+        # 3.5 cannot be tested in CI
+        # https://github.com/MatteoH2O1999/setup-python/issues/49#issuecomment-2209940822
         - python-version: "3.6"
           env:
             TOXENV: py
@@ -33,6 +32,9 @@ jobs:
         - python-version: "3.10"
           env:
             TOXENV: py
+        - python-version: "3.10"
+          env:
+            TOXENV: mypy
         - python-version: "3.11"
           env:
             TOXENV: py
@@ -41,16 +43,19 @@ jobs:
             TOXENV: py
         - python-version: "3.12"
           env:
-            TOXENV: security
+            TOXENV: pre-commit
         - python-version: "3.12"
           env:
             TOXENV: docs
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python ${{ matrix.python-version }}
-        uses: MatteoH2O1999/setup-python@v2
+        uses: MatteoH2O1999/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
+          allow-build: info
+          cache-build: true
+          cache: pip
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip

.pre-commit-config.yaml

@@ -0,0 +1,6 @@
+repos:
+- repo: https://github.com/PyCQA/bandit
+  rev: 1.7.9
+  hooks:
+  - id: bandit
+    args: [-r, -c, .bandit.yml]

scrapy_zyte_smartproxy/middleware.py

@@ -3,10 +3,11 @@
 import warnings
 from base64 import urlsafe_b64decode
 from collections import defaultdict
+from typing import Dict, List
 try:
-    from urllib.request import _parse_proxy
+    from urllib.request import _parse_proxy  # type: ignore
 except ImportError:
-    from urllib2 import _parse_proxy
+    from urllib2 import _parse_proxy  # type: ignore
 
 from six.moves.urllib.parse import urlparse, urlunparse
 from w3lib.http import basic_auth_header
@@ -41,9 +42,9 @@ class ZyteSmartProxyMiddleware(object):
     backoff_step = 15
     backoff_max = 180
     exp_backoff = None
-    force_enable_on_http_codes = []
+    force_enable_on_http_codes = []  # type: List[int]
     max_auth_retry_times = 10
-    enabled_for_domain = {}
+    enabled_for_domain = {}  # type: Dict[str, bool]
     apikey = ""
     zyte_api_to_spm_translations = {
         b"zyte-device": b"x-crawlera-profile",
@@ -261,14 +262,11 @@ def process_request(self, request, spider):
 
     def _is_banned(self, response):
         return (
-            response.status == self.ban_code and
-            response.headers.get('X-Crawlera-Error') == b'banned'
-        )
-
-    def _is_no_available_proxies(self, response):
-        return (
-            response.status == self.ban_code and
-            response.headers.get('X-Crawlera-Error') == b'noslaves'
+            response.status == self.ban_code
+            and response.headers.get('X-Crawlera-Error') == b'banned'
+        ) or (
+            response.status in {520, 521}
+            and response.headers.get('Zyte-Error')
         )
 
     def _is_auth_error(self, response):
@@ -277,6 +275,16 @@ def _is_auth_error(self, response):
             response.headers.get('X-Crawlera-Error') == b'bad_proxy_auth'
         )
 
+    def _throttle_error(self, response):
+        error = response.headers.get('Zyte-Error') or response.headers.get('X-Crawlera-Error')
+        if (
+            response.status in {429, 503}
+            and error
+            and error != b"banned"
+        ):
+            return error.decode()
+        return None
+
     def _process_error(self, response):
         if "Zyte-Error" in response.headers:
             value = response.headers.get('Zyte-Error')
@@ -302,17 +310,20 @@ def process_response(self, request, response, spider):
         key = self._get_slot_key(request)
         self._restore_original_delay(request)
 
-        if self._is_no_available_proxies(response) or self._is_auth_error(response):
-            if self._is_no_available_proxies(response):
-                reason = 'noslaves'
-            else:
+        is_auth_error = self._is_auth_error(response)
+        throttle_error = self._throttle_error(response)
+        if is_auth_error or throttle_error:
+            if is_auth_error:
                 reason = 'autherror'
+            else:
+                assert throttle_error
+                reason = throttle_error.lstrip("/")
             self._set_custom_delay(request, next(self.exp_backoff), reason=reason, targets_zyte_api=targets_zyte_api)
         else:
             self._inc_stat("delay/reset_backoff", targets_zyte_api=targets_zyte_api)
             self.exp_backoff = exp_backoff(self.backoff_step, self.backoff_max)
 
-        if self._is_auth_error(response):
+        if is_auth_error:
             # When Zyte Smart Proxy Manager has issues it might not be able to
             # authenticate users we must retry
             retries = request.meta.get('zyte_smartproxy_auth_retry_times', 0)

setup.cfg

@@ -1,2 +1,16 @@
 [bdist_wheel]
 universal=1
+
+[mypy]
+
+[mypy-pytest.*]
+ignore_missing_imports = True
+
+[mypy-scrapy.*]
+ignore_missing_imports = True
+
+[mypy-twisted.*]
+ignore_missing_imports = True
+
+[mypy-w3lib.*]
+ignore_missing_imports = True

tests/test_all.py

@@ -5,9 +5,9 @@
 from random import choice
 from unittest import TestCase
 try:
-    from unittest.mock import call, patch
+    from unittest.mock import call, patch  # type: ignore
 except ImportError:
-    from mock import call, patch
+    from mock import call, patch  # type: ignore
 
 from w3lib.http import basic_auth_header
 from scrapy.downloadermiddlewares.httpproxy import HttpProxyMiddleware
@@ -666,19 +666,24 @@ def test_is_banned(self):
         mw = self.mwcls.from_crawler(crawler)
         mw.open_spider(self.spider)
         req = self._make_fake_request(self.spider, zyte_smartproxy_enabled=True)
+
         res = Response(req.url, status=200)
         res = mw.process_response(req, res, self.spider)
         self.assertFalse(mw._is_banned(res))
         res = Response(req.url, status=503, headers={'X-Crawlera-Error': 'noslaves'})
         res = mw.process_response(req, res, self.spider)
         self.assertFalse(mw._is_banned(res))
-        res = Response(req.url, status=503, headers={'Zyte-Error': 'noslaves'})
+        res = Response(req.url, status=503, headers={'Zyte-Error': '/limits/over-global-limit'})
         res = mw.process_response(req, res, self.spider)
         self.assertFalse(mw._is_banned(res))
+
         res = Response(req.url, status=503, headers={'X-Crawlera-Error': 'banned'})
         res = mw.process_response(req, res, self.spider)
         self.assertTrue(mw._is_banned(res))
-        res = Response(req.url, status=503, headers={'Zyte-Error': 'banned'})
+        res = Response(req.url, status=520, headers={'Zyte-Error': '/download/temporary-error'})
+        res = mw.process_response(req, res, self.spider)
+        self.assertTrue(mw._is_banned(res))
+        res = Response(req.url, status=521, headers={'Zyte-Error': '/download/internal-error'})
         res = mw.process_response(req, res, self.spider)
         self.assertTrue(mw._is_banned(res))
 
@@ -709,24 +714,38 @@ def test_noslaves_delays(self, random_uniform_patch):
         noslaves_req = Request(url, meta={'download_slot': slot_key})
         assert mw.process_request(noslaves_req, self.spider) is None
         assert httpproxy.process_request(noslaves_req, self.spider) is None
-        headers = {'X-Crawlera-Error': 'noslaves'}
-        noslaves_res = self._mock_zyte_smartproxy_response(
+
+        # delays grow exponentially with any throttling error
+        noslaves_response = self._mock_zyte_smartproxy_response(
             ban_url,
-            status=self.bancode,
-            headers=headers,
+            status=503,
+            headers={'X-Crawlera-Error': 'noslaves'},
         )
-
-        # delays grow exponentially
-        mw.process_response(noslaves_req, noslaves_res, self.spider)
+        mw.process_response(noslaves_req, noslaves_response, self.spider)
         self.assertEqual(slot.delay, backoff_step)
 
-        mw.process_response(noslaves_req, noslaves_res, self.spider)
+        over_use_limit_response = self._mock_zyte_smartproxy_response(
+            ban_url,
+            status=429,
+            headers={'Zyte-Error': '/limits/over-user-limit'},
+        )
+        mw.process_response(noslaves_req, over_use_limit_response, self.spider)
         self.assertEqual(slot.delay, backoff_step * 2 ** 1)
 
-        mw.process_response(noslaves_req, noslaves_res, self.spider)
+        over_domain_limit_response = self._mock_zyte_smartproxy_response(
+            ban_url,
+            status=429,
+            headers={'Zyte-Error': '/limits/over-domain-limit'},
+        )
+        mw.process_response(noslaves_req, over_domain_limit_response, self.spider)
         self.assertEqual(slot.delay, backoff_step * 2 ** 2)
 
-        mw.process_response(noslaves_req, noslaves_res, self.spider)
+        over_global_limit_response = self._mock_zyte_smartproxy_response(
+            ban_url,
+            status=503,
+            headers={'Zyte-Error': '/limits/over-global-limit'},
+        )
+        mw.process_response(noslaves_req, over_global_limit_response, self.spider)
         self.assertEqual(slot.delay, max_delay)
 
         # other responses reset delay
@@ -742,7 +761,7 @@ def test_noslaves_delays(self, random_uniform_patch):
         mw.process_response(ban_req, ban_res, self.spider)
         self.assertEqual(slot.delay, default_delay)
 
-        mw.process_response(noslaves_req, noslaves_res, self.spider)
+        mw.process_response(noslaves_req, noslaves_response, self.spider)
         self.assertEqual(slot.delay, backoff_step)
 
         good_req = Request(url, meta={'download_slot': slot_key})

tox.ini

@@ -1,6 +1,6 @@
 # tox.ini
 [tox]
-envlist = min,py27,py34,py35,py36,py37,py38,py39,py310,py311,py312,docs,security
+envlist = pre-commit,mypy,min,py27,py34,py35,py36,py37,py38,py39,py310,py311,py312,docs
 
 [testenv]
 deps =
@@ -9,6 +9,24 @@ deps =
 commands =
     py.test --doctest-modules --cov=scrapy_zyte_smartproxy {posargs:scrapy_zyte_smartproxy tests}
 
+[testenv:pre-commit]
+basepython = python3
+deps =
+    pre-commit
+commands =
+    pre-commit run {posargs:--all-files}
+
+[testenv:mypy]
+basepython = python3.10
+deps =
+    mypy[python2]<0.980
+    pytest<4.7
+    twisted<=20.3.0
+    types-six<1.16.12
+    w3lib<2
+commands =
+    mypy --py2 {posargs:scrapy_zyte_smartproxy tests}
+
 [testenv:min]
 basepython = python2.7
 deps =