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Docker Intermediate About 25 min +220 XP

Web Container Reports Unhealthy

Compose marks the edge web container unhealthy even though its page answers 200, and the release gate that waits on health is blocked.

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Stage 1 of 3 in Observability Blackout.

Briefing

The observability blackout started with what looks like a false alarm.

The edge web container has been Up for ten minutes and its page answers 200 on port 8086, yet Compose has reported it unhealthy for all ten, which holds the edge release and keeps paging on-call.

The healthcheck block in compose.yaml was rewritten as part of this morning's release.

Dev blames the busybox wget that ships in nginx:alpine and wants to add curl to the image so the check can use that instead.

The fix is yours to find: hints, the recovery checks and the debrief unlock inside the incident.

How it plays

  1. 01

    Get paged

    The alert fires and the clock starts. Read the page and the briefing.

  2. 02

    Investigate

    Work in a simulated shell with realistic output: logs, configs, services.

  3. 03

    Fix it

    Change the system the way you would in production. Hints are there if you get stuck.

  4. 04

    Prove it

    Automated checks verify the recovery, then the debrief explains what happened.

All 61 incidents
Observability Intermediate

API Metrics Disappear from Prometheus

API dashboards have gone flat: Prometheus reports its api scrape target down while the exporter answers from the host.

+230 XP30 minStage 2/3

Observability Advanced

Critical Alerts Arrive Without Pages

Critical alerts reach the alert router and are accepted, but no on-call page has gone out for over an hour.

+250 XP30 minStage 3/3

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