Skip to content

Integration Gateway Timeout and Sync Failures During Scheduled Batch Windows

← Back to categories

Description

Affected users experience failures in scheduled integration jobs that transmit data through the Integration Gateway to downstream API endpoints. Jobs return HTTP 504 Gateway Timeout responses, and in some incidents HTTP 429 rate-limit responses are also observed. Retry attempts fail to clear the resulting backlog, with queue depth climbing rapidly — in observed cases reaching approximately 4,200 pending order records or 14,000 unsynced customer records. The user-visible impact is missing or delayed data in downstream applications, typically noticed during daily reconciliation or when operations dashboards reflect growing backlogs of unprocessed records.

The interaction between authentication state and throttling behavior varies across incidents. In one confirmed case, the Integration Gateway was authenticating outbound API calls with an expired cached token — last rotated over 95 days prior against a 90-day TTL — and the downstream API simultaneously returned 429 throttling once retry storms developed. In another incident, credential failure could not be confirmed; the service account token passed post-incident validation, though runtime authentication state during the failure window remained uncertain. In that case, downstream endpoint latency spiked sharply (median response time climbing from approximately 220 ms to over 4,800 ms) with only isolated 429 responses observed.

Across all observed incidents, the failures are confined to the Integration Gateway processing path and do not affect direct application submissions. Impact begins during scheduled sync windows — typically overnight or early-morning UTC — and persists until token validity, retry behavior, and gateway timeout configurations are corrected or adjusted.

Reported variations

  • In some incidents, both an expired cached API token and HTTP 429 rate-limit responses from the downstream service are confirmed as contributing factors; in others, credential failure is not confirmed and the root cause remains mixed or inconclusive.
  • Some incidents show prominent HTTP 429 rate-limit responses alongside 504 timeouts, while others exhibit primarily 504 and ETIMEDOUT failures with only isolated or absent 429 indicators.
  • Downstream endpoint latency may spike significantly (e.g., p99 exceeding 6 seconds against a 30-second timeout threshold) even when explicit throttling or authentication rejection is not observed.
  • Trace sampling limitations (e.g., 10% sampling rate) may restrict diagnostic coverage of the exact failed requests, leaving the root cause partially unconfirmed.
  • In at least one incident, manual retry handling was initiated by operations staff to limit impact while the sync workflow remained blocked.

Affected environment

Distribution across 3 reported cases:

  • Device / platform: kubernetes (67%), Linux (Docker) (33%)
  • Team: Application Support (33%), order-processing (33%), internal_ops (33%)
  • Region: us-east-1 (100%)

Root cause

A stale expired API token cached on the Integration Gateway caused failed or delayed authenticated requests, while concurrent downstream API rate limiting (HTTP 429) amplified retries and pushed requests past the gateway timeout window. However, the primary cause remains unconfirmed in some incidents because Integration Gateway logs for the failure window and token rotation history were not always available. Available evidence supports an upstream integration timeout condition affecting outbound calls, with the most likely contributors being expired integration credentials, downstream API latency beyond the configured timeout window, or API rate limiting during overnight batch processing.

Diagnostics

Steps used to confirm this root cause:

  1. Confirm the cached Integration Gateway API token was valid and accepted by the downstream API.
    Expected: validation succeeds and the API accepts authenticated calls.
  2. Compare scheduled job execution timing with downstream API response behavior and timeout threshold.
    Expected: API response latency is within the integration timeout window.
  3. Review gateway and job logs for rate-limit responses, retry exhaustion, and queue backpressure indicators.
    Expected: No rate-limit response prevents the integration job from completing.

Resolution

Performed by IT support. Representative resolutions from prior cases:

Example 1

  1. Rotated the Integration Gateway API token for service account via the credentials vault and validated that new outbound requests from igw-prod-east-01 () to the downstream API Service at https://api.corpsync.internal/v2/ingest were successfully authenticated with HTTP 200 responses.
  2. Cleared the stale token cache on gateway node igw-prod-east-01 and changed token refresh cadence from the previous 24-hour interval to 15 minutes to prevent reuse of expired credentials beyond the 90-day TTL boundary.
  3. Updated the integration retry policy from 2 fixed retries (5 s interval) to 5 attempts with exponential backoff and jitter (base 2 s, max 60 s) to reduce retry storms during transient throttling; configuration deployed to igw-prod-east-01 by .
  4. Reprocessed the 14 affected scheduled integration jobs (job group daily-sync-east, run IDs 4401–4414) after the token and retry configuration changes to clear queue backpressure (queue depth returned from 4,200 to ~200) and restore delayed syncs for records reported missing by and the and office users.
  5. Escalated persistent downstream rate-limit spikes (~40 429s/min post-fix) to the downstream service team contact () under ticket DS-789 for follow-up capacity or throttling review; added as watcher on DS-789.

Example 2

  1. Collect and review Integration Gateway logs from node igw-prod-east-01 for 2025-12-12 03:30–04:00 UTC to identify whether the 504 responses align to authentication failures (HTTP 401/403), rate-limit behavior (HTTP 429), or sustained upstream latency exceeding the 30-second timeout threshold. () to coordinate log extraction with the platform team.
  2. Validate the integration token (credential ID: cred--ext-2025) used by service account svc- and compare its rotation or expiry history to the incident start time at 03:40 UTC; rotate the credential immediately via the secrets vault if it is expired or was changed without corresponding gateway configuration updates on igw-prod-east-01.
  3. If credentials are valid, review gateway and downstream API latency during the incident window using Monitoring System traces for pod order-sync-worker-6d8f4 (IP ) and confirm whether response times exceeded the current order-sync timeout threshold of 30 seconds.
  4. Check for rate-limit (HTTP 429) or retry-exhaustion indicators in igw-prod-east-01 gateway records and, if present, reduce burst behavior by tuning order-sync retry intervals from the current 5-second fixed delay to an exponential backoff policy (initial 2s, 60s, jitter enabled) rather than increasing immediate retry count.
  5. After evidence is collected, rerun the failed synchronization backlog (~4,200 pending records) in controlled batches of 200 from pod order-sync-worker-6d8f4 and escalate to the downstream API team (contact: , ) if 504 behavior persists with valid credentials and normal request volume.

Recommendation

Resolved by IT; reference Integration Gateway batch sync failures with HTTP 504/429 responses and backlog accumulation during scheduled overnight processing windows.

← Back to categories