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  1. IL-0552 CircleCI's archival database ran out of storage, slowing workflow and job starts and the display of workflows in the UI
    CircleCI2025
    Symptoms

    At about 23:00 UTC on 21 January 2025, an automated alert reported that the CircleCI database instance holding archived data was almost out of free storage space. From 23:50 UTC customers saw slow starts and cancellations of workflows and jobs, and delays and difficulty viewing workflows in the CircleCI UI, although pipelines for a specific project could still be viewed.

    High latencyIntermittent timeoutsLog floodNode disk fullCloud API rate limit exhausted
    Trigger

    A code change to a function in the archival database on 16 January 2025 unintentionally made it write an excessive number of log messages, and the database filled its storage.

    Root cause
    Faulty deployment
    Component
    DatabaseCI system
    Contributing factor
    Change with a delayed effectExcessive blast radiusOverlapping failures
    Detection

    An automated alert at about 23:00 UTC warned that the archival database was almost out of free storage, before customers were affected. The growing workflows queue was not linked to it at first because a separate alert about request volume fired at about the same time.

    Remediation
    • Scaled up the event consumer that processes the workflows queue at 23:44 UTC
    • Promoted a read replica of the archival database to a standalone primary at 23:55 UTC
    Action items
    • Fix the database function so it no longer writes an excessive number of log messages
    • Add a max duration to the workflows retry policy for archiving so it fails earlier than the default timeout
    • Move workflow archival to an event-based model that decouples it from the workflows service
    • Add forecast and anomaly monitoring for databases that alerts on unusual activity before it reaches critical levels
    Lessons

    The storage alert on the archival database did fire, but the database filled much faster than forecast, so there was little time to act before customers were affected. Because the workflows service called the archival service synchronously, a problem in the archival database slowed the whole workflows service.

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By root cause1

Faulty deployment1 case

Component
CI systemDatabase
Contributing factor
Excessive blast radiusChange with a delayed effectOverlapping failures
Organisation
CircleCI
  1. IL-0552 CircleCI's archival database ran out of storage, slowing workflow and job starts and the display of workflows in the UI
    CircleCI2025