feat(sessions): Add EAP double-write for user sessions#5588
feat(sessions): Add EAP double-write for user sessions#5588noahsmartin wants to merge 4 commits intomasterfrom
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When the `UserSessionsEap` feature flag is enabled, session data is sent both through the legacy metrics pipeline and directly to the snuba-items topic as TRACE_ITEM_TYPE_USER_SESSION TraceItems. This enables migration to the new EAP-based user sessions storage. Includes a Datadog metric `sessions.eap.produced` tagged with `session_type` (update/aggregate) to track EAP writes. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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I didn't review in-depeth, as this we're going to need a different approach.
Session processing can stay as it is, we still need to extract sessions into metrics and aggregate them through the metrics pipeline to keep aggregation in-place.
Right now, you can check the implementation in services/store.rs where session metrics are separated from other "generic" metrics into the sessions topic. This is going to be the entry point where we can start double writing.
Long term, we'd want to have a more strictly typed version of aggregation for metrics, by re-using the generic metrics pipeline but properly typed. This will require some more work though.
Regarding rollout: What is the preferred rollout strategy, via a feature flag? I recommend instead doing a global rollout rate defined in "global config", this is usually the approach we're taking for controlling double writes to Kafka.
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Cursor Bugbot has reviewed your changes and found 1 potential issue.
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| let received = Some(prost_types::Timestamp { | ||
| seconds: now.as_secs() as i64, | ||
| nanos: 0, | ||
| }); |
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EAP received timestamp uses current time instead of actual receive time
Medium Severity
The received timestamp for EAP TraceItems is set to now (current time when emitting to EAP) instead of using bucket.metadata.received_at (the actual time Relay received the data). Other EAP producers like logs, trace attachments, and trace metrics consistently use the actual received_at time from their context. The bucket's received_at metadata is available and already used for delay tracking in the legacy pipeline (lines 539-544), but the EAP emission ignores it. This causes the received field in EAP to reflect when data was processed for Kafka production rather than when it was originally received, leading to incorrect timestamps and inconsistency between legacy and EAP data.
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When the
UserSessionsEapfeature flag is enabled, session data is sent both through the legacy metrics pipeline and directly to the snuba-items topic as TRACE_ITEM_TYPE_USER_SESSION TraceItems.This enables migration to the new EAP-based user sessions storage.
Includes a Datadog metric
Cursor Bugbot found 2 potential issues for commit 1a745cdsessions.eap.producedtagged withsession_type(update/aggregate) to track EAP writes.