Ensuring Reliable Session Replay Usage and Diagnosing Dropped Replays in Sentry
Session Replay is a powerful feature in Sentry that allows you to capture and review user interactions. However, ensuring its reliability and diagnosing potential issues like dropped replays can be critical for effective usage. This guide provides an overview of how Spike Protection interacts with Session Replay and offers troubleshooting steps for diagnosing replay discards.
Overview of Spike Protection and Session Replay
Spike Protection is a feature in Sentry designed to manage quotas for errors, transactions, spans, and attachments. However, it does not apply to Session Replay. During a Sentry trial, category quotas are unlimited, and Spike Protection is inactive. Even when active, Spike Protection does not control Session Replay, so it will not cause dropped replays.
Diagnosing Replay Discards
Dropped replays can occur due to two primary reasons: Internal SDK Errors or network-related issues. Below are steps to diagnose and address these issues:
1. Diagnosing Internal SDK Errors
Internal SDK Errors occur during in-browser recording before the replay data is uploaded. To diagnose these errors:
Enable diagnostic capture for a small test group (e.g., a canary cohort).
Use the Replay integration option _experiments: { captureExceptions: true } to capture worker or buffer errors.
Tag sessions in the test group (e.g., replay_diagnostics_canary) to review resulting issues and analyze the breakdown of discards.
This approach helps identify and resolve SDK-related issues effectively.
2. Diagnosing Network Errors
Network-related replay discards occur when uploads fail to complete. To address these issues:
Review your proxy or edge path for timeouts or disconnects
Ensure that nginx timeouts are set sufficiently high to handle large uploads.
Consider disabling request buffering for large bodies in nginx.
If using an edge service like Cloudflare in front of nginx, verify that the edge proxy timeout is greater than or equal to nginx’s proxy_read_timeout.
Check for any Web Application Firewall (WAF) blocks on large POST requests and confirm that edge upload size limits are not exceeded.
These steps help ensure that network configurations do not interfere with Session Replay uploads.
Best Practices for Ensuring Replay Reliability
Regularly monitor Session Replay metrics and logs to identify potential issues early.
Use small test groups to validate changes or enable diagnostic features before rolling them out broadly.
Optimize your network and proxy configurations to handle large data uploads efficiently.
By following these guidelines, you can ensure reliable Session Replay usage and effectively diagnose and resolve issues related to dropped replays.