2023-02-15: www-gitlab-com pipelines failing with "Undefined error"

Current Status

The incident was resolved by disabling the feature flag that resulted in the failed pipelines when enabled.

📝 Summary for CMOC notice / Exec summary:

1. Customer Impact: No direct customer impact as pipeline failures were limited to the following projects: gitlab-org/gitlab, gitlab-org/gitlab-foss, gitlab-com/www-gitlab-com.
2. Service Impact: ServiceGitLab Rails
3. Impact Duration: 20:17 - 21:04 (47 minutes)
4. Root cause: gitlab-org/gitlab!111726 (merged) introduced a change that resulted in an exception when the feature flag was enabled for projects whose .gitlab-ci.yml included projects that did not have the feature flag enabled. See #8405 (comment 1280469809) for more detail.
5. Other relevant links:
   • Related feature flag issue: gitlab-org/gitlab#391517 (closed)
   • Example of failed pipeline in handbook repo: https://gitlab.com/gitlab-com/www-gitlab-com/-/pipelines/778955304
   • Example of failed pipeline in gitlab-org/gitlab: https://gitlab.com/gitlab-org/gitlab/-/pipelines/778991423

📚 References and helpful links

Recent Events (available internally only):

• Feature Flag Log - Chatops to toggle Feature Flags Documentation
• Infrastructure Configurations
• GCP Events (e.g. host failure)

Deployment Guidance

• Deployments Log | Gitlab.com Latest Updates
• Reach out to Release Managers for S1/S2 incidents to discuss Rollbacks and/or Hot Patching | Rollback Runbook | Hot Patch Runbook

Use the following links to create related issues to this incident if additional work needs to be completed after it is resolved:

• Corrective action ❙ Infradev
• Incident Review ❙ Infra investigation followup
• Confidential Support contact ❙ QA investigation

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