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[Postmortem] OpenFoodFacts.net down (#1)

Date: 03/10/2021

Authors: ocervello,

Status: Complete, action items in progress

Summary: openfoodfacts.net down after Docker storage driver configuration change. Proxmox containers off-net, robotoff-net, robotoff-dev, mongo-dev, and monitoring are unreachable.

Impact: Integration tests failing on openfoodfacts-dart (example), pre-prod environment (openfoodfacts.net) down.

Root Causes: Cascading failure probably due to Docker storage driver configuration change from vfs to fuse-overlayfs, and probably an incompatibility between LXC, Docker and fuse-overlayfs, causing containers to crash, and unable to SSH. Exact root cause is still unknown, as some containers using fuse-overlayfs have not crashed.

Trigger: Unknown. First outage happened 3 days after the Docker storage driver change.

Resolution

  • Short term: revert Docker storage driver configuration from fuse-overlayfs to vfs.
  • Long term: run Docker containers in a QEMU host instead.

Detection: message on Slack #infrastructure channel + openfoodfacts-dart integration tests failing with timeouts.

Action Items

Action Item Type Owner Status
Revert Docker storage driver to vfs mitigate olivier DONE
Snapshot off-net CT and start a new CT from the snapshot mitigate charles FAILED
Create vanilla CT with storage driver vfs and re-deploy openfoodfacts.net on it + ZFS Mounts + NGINX config change mitigate charles,olivier,stephane,christian IN PROGRESS
Open ticket to Proxmox forums to investigate the crash process charles TODO
Run all crashed Docker containers on QEMU VM for stability + ZFS mounts + NGINX configuration prevent olivier,charles,stephane,christian #62

Lessons Learned

What went well

  • Community + staff got quickly alerted of openfoodfacts.net being down
  • Worked together to solve the issues

What went wrong

  • No explicit alert message was sent to productopener-alerts Slack channel → need integration tests on openfoodfacts-server repository
  • Too many CTs brought down simultaneously - should have done the storage engine change on only 1 host and wait
  • Proxmox container cloning failed, increasing the ETTR (Estimated Time To Repair)
  • Proxmox container failed to reboot, increasing the ETTR
  • Too much noise on productopener-alerts, failed deployments were missed.
  • Sysadmins were not aware about all the impacts of off-net downtime.
  • No single point to track the investigation and resolution (e.g. GitHub issue)

Where we got lucky

  • Did not bring down production as it is still running on the Free machines.
  • Automated deployments allowed us to re-deploy openfoodfacts.net pretty fast
  • The right people were available.

What we learned

  • Assuming the root cause is correct: Proxmox LXC + Docker + ZFS + fuse-overlayfs storage driver can trigger severe issues where even Proxmox administration tools do not work (clones, snapshots, etc…)

Timeline

29-09-2021 (All times CEST)

  • 15:46 ROOT CAUSE — Docker storage driver switch from vfs to fuse-overlayfs made on all CTs w/ Docker deployments.

03-10-2021 (All times CEST)

  • 02:17 OUTAGE BEGINS — Automated message on #infrastructure-alerts Slack channel about timeouts when trying to access world.openfoodfacts.net
  • 19:16 OUTAGE BEGINS — Manual message by contributor on #infrastructure Slack channel about timeouts when trying to access world.openfoodfacts.net

04-10-2021 (All times CEST)

  • 9:23 Message on #infrastructure Slack channel that multiple containers are unresponsive.

06-10-2021 (All times CEST)

  • 14:36 OUTAGE MITIGATED, deployed openfoodfacts.net and a new machine. Mounts are still missing on disk.
  • 14:45 Decision taken to switch Docker containers to QEMU VM.
  • 15:36 Creation of QEMU VM 128GB RAM, 8 cores, 196GB drive.

07-10-2021 (All times CEST)

  • 09:00 Starting to manually deploy openfoodfacts-server, robotoff, robotoff-ann and monitoring containers on QEMU VM
  • 09:30 Openfoodfacts server is deployed on QEMU VM
  • 10:20 Robotoff deployment is blocked by a CPU flag issue (avx flag needed for Tensorflow library)

Supporting information:

  • Document a clear realistic “acceptable downtime” for each CT/VM/machines we manage (using the existing spreadsheet).
  • Document the main owner and his/her co-owner (?) of each machine, ie people able to restore a service within the “acceptable downtime” and owning this responsibility.
  • Decide how we document the infrastructure (not well decided yet).
  • Is it possible to publish only real alerts in #infrastructure-alerts? Eg, only publish alerts if the machine is down for more than 15 minutes. Most of the alerts seems to be false positives.
  • Define a process to resolve future incidents (e.g. should we systematically file a github issue for each incident?)