feat: Added support for CDN cache purging (#26930)

posthog/models/remote_config.py

@@ -7,6 +7,7 @@
 from django.http import HttpRequest
 from django.utils import timezone
 from prometheus_client import Counter
+import requests
 from sentry_sdk import capture_exception
 import structlog
 
@@ -38,6 +39,12 @@
     labelnames=["result"],
 )
 
+REMOTE_CONFIG_CDN_PURGE_COUNTER = Counter(
+    "posthog_remote_config_cdn_purge",
+    "Number of times the remote config CDN purge task has been run",
+    labelnames=["result"],
+)
+
 
 logger = structlog.get_logger(__name__)
 
@@ -355,6 +362,8 @@ def sync(self):
 
             cache.set(cache_key_for_team_token(self.team.api_token, "config"), config, timeout=CACHE_TIMEOUT)
 
+            self._purge_cdn()
+
             # TODO: Invalidate caches - in particular this will be the Cloudflare CDN cache
             self.synced_at = timezone.now()
             self.save()
@@ -366,6 +375,37 @@ def sync(self):
             CELERY_TASK_REMOTE_CONFIG_SYNC.labels(result="failure").inc()
             raise
 
+    def _purge_cdn(self):
+        if (
+            not settings.REMOTE_CONFIG_CDN_PURGE_ENDPOINT
+            or not settings.REMOTE_CONFIG_CDN_PURGE_TOKEN
+            or not settings.REMOTE_CONFIG_CDN_PURGE_DOMAINS
+        ):
+            return
+
+        logger.info(f"Purging CDN for team {self.team_id}")
+
+        data: dict[str, Any] = {"files": []}
+
+        for domain in settings.REMOTE_CONFIG_CDN_PURGE_DOMAINS:
+            # Check if the domain starts with https:// and if not add it
+            full_domain = domain if domain.startswith("https://") else f"https://{domain}"
+            data["files"].append({"url": f"{full_domain}/array/{self.team.api_token}/config"})
+            data["files"].append({"url": f"{full_domain}/array/{self.team.api_token}/config.js"})
+            data["files"].append({"url": f"{full_domain}/array/{self.team.api_token}/array.js"})
+
+        try:
+            requests.post(
+                settings.REMOTE_CONFIG_CDN_PURGE_ENDPOINT,
+                headers={"Authorization": f"Bearer {settings.REMOTE_CONFIG_CDN_PURGE_TOKEN}"},
+                data=data,
+            )
+        except Exception:
+            logger.exception(f"Failed to purge CDN for team {self.team_id}")
+            REMOTE_CONFIG_CDN_PURGE_COUNTER.labels(result="failure").inc()
+        else:
+            REMOTE_CONFIG_CDN_PURGE_COUNTER.labels(result="success").inc()
+
     def __str__(self):
         return f"RemoteConfig {self.team_id}"
 

posthog/models/test/test_remote_config.py

@@ -440,6 +440,29 @@ def test_only_includes_recording_for_approved_domains(self):
             config = self.remote_config.get_config_via_token(self.team.api_token, request=mock_request)
             assert not config["sessionRecording"]
 
+    @patch("posthog.models.remote_config.requests.post")
+    def test_purges_cdn_cache_on_sync(self, mock_post):
+        with self.settings(
+            REMOTE_CONFIG_CDN_PURGE_ENDPOINT="https://api.cloudflare.com/client/v4/zones/MY_ZONE_ID/purge_cache",
+            REMOTE_CONFIG_CDN_PURGE_TOKEN="MY_TOKEN",
+            REMOTE_CONFIG_CDN_PURGE_DOMAINS=["cdn.posthog.com", "https://cdn2.posthog.com"],
+        ):
+            self.remote_config.sync()
+            mock_post.assert_called_once_with(
+                "https://api.cloudflare.com/client/v4/zones/MY_ZONE_ID/purge_cache",
+                headers={"Authorization": "Bearer MY_TOKEN"},
+                data={
+                    "files": [
+                        {"url": "https://cdn.posthog.com/array/phc_12345/config"},
+                        {"url": "https://cdn.posthog.com/array/phc_12345/config.js"},
+                        {"url": "https://cdn.posthog.com/array/phc_12345/array.js"},
+                        {"url": "https://cdn2.posthog.com/array/phc_12345/config"},
+                        {"url": "https://cdn2.posthog.com/array/phc_12345/config.js"},
+                        {"url": "https://cdn2.posthog.com/array/phc_12345/array.js"},
+                    ]
+                },
+            )
+
 
 class TestRemoteConfigJS(_RemoteConfigBase):
     def test_renders_js_including_config(self):

posthog/settings/web.py

@@ -398,3 +398,8 @@
 
 # disables frontend side navigation hooks to make hot-reload work seamlessly
 DEV_DISABLE_NAVIGATION_HOOKS = get_from_env("DEV_DISABLE_NAVIGATION_HOOKS", False, type_cast=bool)
+
+
+REMOTE_CONFIG_CDN_PURGE_ENDPOINT = get_from_env("REMOTE_CONFIG_CDN_PURGE_ENDPOINT", "")
+REMOTE_CONFIG_CDN_PURGE_TOKEN = get_from_env("REMOTE_CONFIG_CDN_PURGE_TOKEN", "")
+REMOTE_CONFIG_CDN_PURGE_DOMAINS = get_list(os.getenv("REMOTE_CONFIG_CDN_PURGE_DOMAINS", ""))