fix(code-review): Add cache to dedupe github webhook events#107734
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suejung-sentry wants to merge 3 commits intomasterfrom
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fix(code-review): Add cache to dedupe github webhook events#107734suejung-sentry wants to merge 3 commits intomasterfrom
suejung-sentry wants to merge 3 commits intomasterfrom
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Feb 5, 2026
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| def _get_webhook_seen_cluster() -> RedisCluster[str] | StrictRedis[str]: | ||
| return redis_clusters.get("default") |
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Feb 6, 2026
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| logger = logging.getLogger(__name__) | ||
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| WEBHOOK_SEEN_TTL_SECONDS = 20 |
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I picked 20 seconds because per the redash, if there ever is a dupe, they happen within 500 milliseconds of each other. I thought 20 seconds would comfortably cover that and any errant github redelivery behavior
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This PR handles webhook delivery deduplication by introducing redis idempotency keys for the github webhook id.
GitHub guarantees "at-least-once" delivery so may send duplicate webhooks. We have seen anecdotally that seer can receive multiple requests for a single commit (from a pull_request.synchronize event) within 500 milliseconds of each other (redash).
It's unclear whether GitHub is delivering the webhook twice or something in our control-->regional forwarding queues is causing redelivery. In any case, it seems likely that the same payload is getting processed with the same github webhook id. So use that as the idempotency key.
I considered whether we should go for a lock instead. The downside of that is the lock would release after the function returns, which may happen sooner than the 500 milliseconds we are currently seeing dupes in.
So instead in this PR, we just say any webhook with the same webhook id delivered within the same 20 second window are not replayed and re-forwarded to seer.
I chose 20 second TTL to cover the 500 milliseconds period and any errant github retry+backoff behavior.
Redis should be able to handle this load which is one SET per github webhook that makes it past our "preflight" feature enablement filters (a max hour is around 2,000 code reviews, so say 1 request per second in a peak hour). Also the keys are small with a short TTL.
Closes CW-673