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53. CI/CD Failure Prevention Framework

Date: 2025-11-12

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Status

Accepted

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Category

Infrastructure & Deployment

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Context

On 2025-11-12, we experienced multiple CI/CD pipeline failures that blocked development:
  • 4 out of 10 workflows failed on the same commit
  • Pre-commit hooks failed due to missing dependencies
  • Terraform validation failed with configuration errors
  • E2E tests failed due to infrastructure dependency issues
  • Service principal tests intermittently failed with 401 errors in parallel execution

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Root Causes

  1. Documentation: 253 untagged code blocks in .mdx files
  2. Terraform: Duplicate required_providers, invalid variable validations, version conflicts
  3. Pre-commit: Missing pyyaml dependency in validation hooks
  4. Tests: Missing infrastructure checks, pytest-xdist state pollution

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Decision

Adopt a multi-layered CI/CD Failure Prevention Framework based on TDD principles:

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1. Regression Test Suite

  • tests/regression/test_documentation_code_blocks.py (5 tests)
  • tests/regression/test_terraform_configuration.py (8 tests)
  • tests/regression/test_precommit_hook_dependencies.py (9 tests)
  • tests/regression/test_service_principal_test_isolation.py (7 tests)
Total: 29 regression tests preventing recurrence

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2. Proactive CI Health Check

  • scripts/ci_health_check.py - Validates before CI runs
  • Detects issues in < 30 seconds
  • Provides actionable fix suggestions

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3. Test Infrastructure Isolation

  • Tests declare dependencies via fixtures
  • Skip gracefully when infrastructure unavailable
  • Clear distinction between code bugs and environment issues

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4. Configuration Standards

  • Terraform: One terraform block per file, no cross-variable validations
  • Pre-commit: Use language: python with explicit dependencies
  • Documentation: All code blocks must have language tags

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Consequences

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Positive

  • Issues from 2025-11-12 cannot recur (regression tests catch them)
  • Faster feedback (< 30 seconds vs full CI pipeline)
  • Better developer experience (clear errors + fix suggestions)
  • Improved CI reliability (fewer false failures)
  • Knowledge preservation (failures documented in tests)

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Negative

  • Additional maintenance burden (29 regression tests)
  • Slightly slower commits (~5 seconds for pre-commit)
  • Learning curve for team (new patterns and tools)

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Implementation

See ADR-0053 .mdx file in docs/architecture/ for comprehensive details.

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References

Last Updated: 2025-11-12