purge cloudflare on deploy

Procfile

@@ -1,2 +1,2 @@
-release: python3 manage.py migrate
+release: python3 manage.py migrate && python3 manage.py purgeCloudflare
 web: gunicorn rcvis.wsgi

common/cloudflare.py

@@ -66,20 +66,37 @@ def purge_paths_cache(cls, paths):
         if not cls._is_api_enabled():
             return
 
+        info = f"{len(paths)} starting with {paths[0]}"
+        cls._send_purge_request({'files': cls.get_absolute_paths_for(paths)}, info)
+
+    @classmethod
+    def purge_entire_cache(cls):
+        """
+        Purges everything: every page and every static file, on every domain.
+        Run on each deploy (see the Procfile release phase): rendered HTML
+        references hashed static files that change on deploy, and an edge copy
+        cached before the deploy would keep satisfying browsers' revalidation
+        requests with 304s, pinning HTML that points at deleted assets.
+        """
+        cache.clear()
+
+        if not cls._is_api_enabled():
+            return
+
+        cls._send_purge_request({'purge_everything': True}, 'purge_everything')
+
+    @classmethod
+    def _send_purge_request(cls, data, info):
+        """ POSTs a purge request to the cloudflare API and logs the outcome """
         zoneId = settings.CLOUDFLARE_ZONE_ID
         apiUrl = f"https://api.cloudflare.com/client/v4/zones/{zoneId}/purge_cache"
 
-        # Absolute URLs
-        data = {'files': cls.get_absolute_paths_for(paths)}
-
-        # Send it off
         response = requests.post(
             apiUrl,
             headers=cls._get_auth_headers(),
             data=json.dumps(data),
             timeout=8)
 
-        info = f"{len(paths)} starting with {paths[0]}"
         if response.status_code == 200:
             logger.info("Cleared cloudflare cache for %s: %s", info, response.json())
         else:

visualizer/management/commands/purgeCloudflare.py

@@ -0,0 +1,23 @@
+"""
+Management command to purge the entire Cloudflare cache, run on each deploy
+via the Procfile release phase. Rendered HTML references hashed static files
+that change on deploy, so edge copies cached before the deploy would keep
+serving (and 304-renewing) HTML that points at deleted assets.
+"""
+from django.core.management.base import BaseCommand
+
+from common.cloudflare import CloudflareAPI
+
+
+class Command(BaseCommand):
+    """ The command itself """
+
+    def handle(self, *args, **kwargs):
+        # Never fail over a cache purge: a failed release phase would block
+        # the very deploy this purge exists to clean up after.
+        try:
+            CloudflareAPI.purge_entire_cache()
+        except Exception as exception:  # pylint: disable=broad-except
+            self.stderr.write(f'Cloudflare purge failed: {exception}\n')
+            return
+        self.stdout.write('Purged cloudflare cache\n')

visualizer/tests/testSimple.py

@@ -502,6 +502,47 @@ def test_cloudflare_purge(self, requestPostResponse):
                                                data=json.dumps(expectedData),
                                                timeout=8)
 
+    @patch('requests.post')
+    def test_cloudflare_purge_everything_on_deploy(self, requestPostResponse):
+        """
+        The deploy-time management command asks cloudflare to purge everything,
+        so edge copies of pre-deploy HTML can't keep 304-renewing browsers'
+        stale copies that point at deleted static assets.
+        """
+        requestPostResponse.side_effect = TestHelpers.create_request_mock({'a': 0}, 200)
+
+        with self.settings(
+                CLOUDFLARE_AUTH_TOKEN='mytoken',
+                CLOUDFLARE_ZONE_ID='zoneid'):
+            out = StringIO()
+            call_command('purgeCloudflare', stdout=out)
+            self.assertIn('Purged cloudflare cache', out.getvalue())
+
+        expectedUrl = 'https://api.cloudflare.com/client/v4/zones/zoneid/purge_cache'
+        expectedHeaders = {
+            "Content-Type": "application/json",
+            "Authorization": "Bearer mytoken"
+        }
+        requestPostResponse.assert_called_with(expectedUrl,
+                                               headers=expectedHeaders,
+                                               data=json.dumps({'purge_everything': True}),
+                                               timeout=8)
+
+    @patch('requests.post')
+    def test_cloudflare_purge_failure_does_not_fail_release(self, requestPostResponse):
+        """
+        A cloudflare outage must not fail the command: it runs in the release
+        phase, and a failed release would block the deploy itself.
+        """
+        requestPostResponse.side_effect = IOError("cloudflare is down")
+
+        with self.settings(
+                CLOUDFLARE_AUTH_TOKEN='mytoken',
+                CLOUDFLARE_ZONE_ID='zoneid'):
+            err = StringIO()
+            call_command('purgeCloudflare', stderr=err)
+            self.assertIn('Cloudflare purge failed', err.getvalue())
+
     def test_conditional_get_returns_304_when_fresh(self):
         """
         When the client sends If-Modified-Since matching the object's updatedAt,