SendGrid Events重复触发问题咨询：相同消息ID事件处理后再次执行

Hey there, let's tackle those duplicate SendGrid Events issues you're facing—they're a common pain point, but we can work through them with targeted fixes.

Why This Happens (Quick Context) #

Before diving into solutions, let's cover the most common root causes:

• Webhook Acknowledgment Timeouts: SendGrid retries events if your endpoint doesn't return a 200 OK within 10 seconds (it can retry up to 3 times with increasing delays).
• Accidental Duplicate Webhooks: If you've set up multiple identical event webhooks in SendGrid's dashboard, the same event will get pushed multiple times.
• Missing Idempotency Checks: Your service might not be tracking which events it's already processed, leading to duplicate handling even if SendGrid sends duplicates.

1. Fixing General Multiple Event Triggers #

Here's how to stop events from being pushed repeatedly:

• Prioritize Fast 200 OK Responses: Don't run heavy business logic directly in your webhook endpoint. Instead, acknowledge the event immediately with a 200 OK, then queue the event for asynchronous processing (like using a message broker or background job). This prevents SendGrid from triggering retries due to timeouts.
• Audit Your Webhook Config: Head to SendGrid's dashboard > Settings > Mail Settings > Event Webhook and check if you have duplicate webhook entries targeting the same endpoint and event types. Delete any duplicates you find.
• Check SendGrid's Event Logs: Use the built-in logs under the Event Webhook settings to see if retries are happening because your service returned non-200 status codes (like 500 errors or timeouts). This will confirm if the issue is on your end or SendGrid's retry logic.

2. Handling Duplicate Delivered/Open Events with the Same Message ID #

For cases where identical delivered or open events (same message ID, event type, and timestamp) are being re-sent:

• First, Distinguish Legitimate vs. Duplicate Events: Note that multiple open events with different timestamps are normal (they mean the user opened the email multiple times). Only worry about duplicates that have identical timestamps, message IDs, and event types.
• Implement Idempotent Processing: Create a unique key for each event using the combination of message_id + event_type + timestamp, and store this key in a database or cache (like Redis). When a new event comes in:
  1. Check if the key already exists.
  2. If it does, return 200 OK immediately without processing the event again.
  3. If it doesn't, process the event and save the key to mark it as handled.
• Verify Delivered Event Retries: If delivered events are repeating, it's almost always due to SendGrid retrying because your initial response failed. Double-check that your endpoint is reliably returning 200 OK the first time it receives the event.

Debugging Tips to Confirm the Issue #

• Log Everything on Your End: Add detailed logs for every event your service receives, including message_id, event_type, timestamp, and the response status you sent back. Compare these logs with SendGrid's event logs to pinpoint where duplicates are coming from.
• Test with SendGrid's Event Webhook Tester: Use the tester in SendGrid's dashboard to send a test event and verify that your endpoint responds quickly and correctly. This can help you rule out endpoint issues before they cause production duplicates.

内容的提问来源于stack exchange，提问作者anshul suneja