Charon/docs/reports/ci_failure_diagnosis.md

CI/CD Failure Diagnosis Report

Date: December 14, 2025 GitHub Actions Run: #20204673793 Workflow: benchmark.yml (Go Benchmark) Status: ❌ Failed Commit: 8489394 - Merge pull request #396

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Executive Summary

The CI/CD failure is caused by an incomplete Go module migration from github.com/oschwald/geoip2-golang v1 to v2. The Renovate bot PR #396 updated go.mod to use v2 of the package, but:

1. The actual source code still imports the v1 package path (without /v2)
2. This created a mismatch where go.mod declares v2 but the code imports v1
3. The module resolution system cannot find the v1 package because it's been removed from go.mod

Root Cause: Import path incompatibility between major versions in Go modules. When upgrading from v1 to v2 of a Go module, both the go.mod AND the import statements in source files must be updated to include the /v2 suffix.

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Workflow Description

What the Failing Workflow Does

The benchmark.yml workflow (Go Benchmark) performs:

1. Checkout repository code
2. Set up Go environment (v1.25.5)
3. Run benchmarks on backend code using go test -bench=.
4. Store benchmark results (only on pushes to main branch)
5. Run performance assertions to catch regressions

Purpose: Continuous performance monitoring to detect regressions before they reach production.

Trigger: Runs on push/PR to main or development branches when backend files change.

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Failing Step Details

Step: "Performance Regression Check"

Error Messages (9 identical errors):

no required module provides package github.com/oschwald/geoip2-golang; to add it:
    go get github.com/oschwald/geoip2-golang

Exit Code: 1 (compilation failure)

Phase: Build/compilation phase during go test execution

Affected Files:

• /projects/Charon/backend/internal/services/geoip_service.go (line 9)
• /projects/Charon/backend/internal/services/geoip_service_test.go (line 10)

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Renovate Changes Analysis

PR #396: Update github.com/oschwald/geoip2-golang to v2

Branch: renovate/github.com-oschwald-geoip2-golang-2.x Merge Commit: 8489394 into development

Changes Made by Renovate:

# backend/go.mod
- github.com/oschwald/geoip2-golang v1.13.0
+ github.com/oschwald/geoip2-golang/v2 v2.0.1

Issue: Renovate added the v2 dependency but also left a duplicate entry, resulting in:

require (
    // ... other deps ...
    github.com/oschwald/geoip2-golang/v2 v2.0.1  // ← ADDED BY RENOVATE
    github.com/oschwald/geoip2-golang/v2 v2.0.1  // ← DUPLICATE!
    // ... other deps ...
)

The v1 dependency was removed from go.mod.

Related Commits:

• 8489394: Merge PR #396
• dd9a559: Renovate branch with geoip2 v2 update
• 6469c6a: Previous development state (had v1)

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Root Cause Analysis

The Problem

Go modules use semantic import versioning. For major version 2 and above, the import path must include the major version:

v1 (or unversioned):

import "github.com/oschwald/geoip2-golang"

v2+:

import "github.com/oschwald/geoip2-golang/v2"

What Happened

1. Before PR #396:

   • go.mod: contained github.com/oschwald/geoip2-golang v1.13.0
   • Source code: imports github.com/oschwald/geoip2-golang
   • ✅ Everything aligned and working

2. After PR #396 (Renovate):

   • go.mod: contains github.com/oschwald/geoip2-golang/v2 v2.0.1 (duplicate entry)
   • Source code: still imports github.com/oschwald/geoip2-golang (v1 path)
   • ❌ Mismatch: code wants v1, but only v2 is available

3. Go Module Resolution:

   • When Go sees import "github.com/oschwald/geoip2-golang", it looks for a module matching that path
   • go.mod only has github.com/oschwald/geoip2-golang/v2
   • These are different module paths in Go's eyes
   • Result: "no required module provides package"

Verification

Running go mod tidy shows:

go: finding module for package github.com/oschwald/geoip2-golang
go: found github.com/oschwald/geoip2-golang in github.com/oschwald/geoip2-golang v1.13.0
unused github.com/oschwald/geoip2-golang/v2

This confirms:

• Go finds v1 when analyzing imports
• v2 is declared but unused
• The imports and go.mod are out of sync

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Impact Assessment

Directly Affected

• ✅ security-weekly-rebuild.yml (the file currently open in editor): NOT affected

  • This workflow builds Docker images and doesn't run Go tests directly
  • It will succeed if the Docker build process works

• ❌ benchmark.yml: FAILING

  • Cannot compile backend code
  • Blocks performance regression checks

Potentially Affected

All workflows that compile or test backend Go code:

• go-build.yml or similar build workflows
• go-test.yml or test workflows
• Any integration tests that compile the backend
• Docker builds that include go build steps inside the container

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Why Renovate Didn't Handle This

Renovate's Behavior:

• Renovate excels at updating dependency declarations (in go.mod, package.json, etc.)
• It updates version numbers and dependency paths in configuration files
• However, it does not modify source code imports automatically

Why Import Updates Are Manual:

1. Import path changes are code changes, not config changes
2. Requires semantic understanding of the codebase
3. May involve API changes that need human review
4. Risk of breaking changes in major version bumps

Expected Workflow for Major Go Module Updates:

1. Renovate creates PR updating go.mod with v2 path
2. Human reviewer identifies this requires import changes
3. Developer manually updates all import statements
4. Tests confirm everything works with v2 API
5. PR is merged

What Went Wrong:

• Renovate was configured for automerge on patch updates
• This appears to have been a major version update (v1 → v2)
• Either automerge rules were too permissive, or manual review was skipped
• The duplicate entry in go.mod suggests a merge conflict or incomplete update

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Recommended Fix Approach

Step 1: Update Import Statements

Replace all occurrences of v1 import path with v2:

Files to Update:

• backend/internal/services/geoip_service.go (line 9)
• backend/internal/services/geoip_service_test.go (line 10)

Change:

// FROM:
import "github.com/oschwald/geoip2-golang"

// TO:
import "github.com/oschwald/geoip2-golang/v2"

Step 2: Remove Duplicate go.mod Entry

File: backend/go.mod

Issue: Line 13 and 14 both have:

github.com/oschwald/geoip2-golang/v2 v2.0.1
github.com/oschwald/geoip2-golang/v2 v2.0.1  // ← DUPLICATE

Fix: Remove one duplicate entry.

Step 3: Run go mod tidy

cd backend
go mod tidy

This will:

• Clean up any unused dependencies
• Update go.sum with correct checksums for v2
• Verify all imports are satisfied

Step 4: Verify the Build

cd backend
go build ./...
go test ./...

Step 5: Check for API Changes

IMPORTANT: Major version bumps may include breaking API changes.

Review the geoip2-golang v2.0.0 release notes for:

• Renamed functions or types
• Changed function signatures
• Deprecated features

Update code accordingly if the API has changed.

Step 6: Test Affected Workflows

Trigger the benchmark workflow to confirm it passes:

git push origin development

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Prevention Recommendations

1. Update Renovate Configuration

Add a rule to prevent automerge on major version updates for Go modules:

{
  "packageRules": [
    {
      "description": "Manual review required for Go major version updates",
      "matchManagers": ["gomod"],
      "matchUpdateTypes": ["major"],
      "automerge": false,
      "labels": ["dependencies", "go", "manual-review", "breaking-change"]
    }
  ]
}

This ensures major updates wait for human review to handle import path changes.

2. Add Pre-merge CI Check

Ensure the benchmark workflow (or a build workflow) runs on PRs to development:

# benchmark.yml already has this
pull_request:
  branches:
    - main
    - development

This would have caught the issue before merge.

3. Document Major Update Process

Create a checklist for major Go module updates:

• Update go.mod version
• Update import paths in all source files (add /v2, /v3, etc.)
• Run go mod tidy
• Review release notes for breaking changes
• Update code for API changes
• Run full test suite
• Verify benchmarks pass

4. Go Module Update Script

Create a helper script to automate import path updates:

# scripts/update-go-major-version.sh
# Usage: ./scripts/update-go-major-version.sh github.com/oschwald/geoip2-golang 2

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Additional Context

Go Semantic Import Versioning

From Go Modules v2+ documentation:

If a module is version v2 or higher, the major version of the module must be included as a /vN at the end of the module paths used in go.mod files and in the package import path.

This is a fundamental requirement of Go modules, not a limitation or bug. It ensures:

• Clear indication of major version in code
• Ability to import multiple major versions simultaneously
• Explicit acknowledgment of breaking changes

Similar Past Issues

This is a common pitfall when updating Go modules. Other examples in the Go ecosystem:

• gopkg.in packages (use /v2, /v3 suffixes)
• github.com/go-chi/chi → github.com/go-chi/chi/v5
• github.com/gorilla/mux → github.com/gorilla/mux/v2 (if they release one)

Why the Duplicate Entry?

The duplicate in go.mod likely occurred because:

1. Renovate added the v2 dependency
2. A merge conflict or concurrent edit preserved an old v2 entry
3. go mod tidy was not run after the merge
4. The duplicate doesn't cause an error (Go just ignores duplicates)

However, the real issue is the import path mismatch, not the duplicate.

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Conclusion

This is a textbook case of incomplete Go module major version migration. The fix is straightforward but requires manual code changes that automation tools like Renovate cannot safely perform.

Estimated Time to Fix: 10-15 minutes

Risk Level: Low (fix is well-defined and testable)

Priority: High (blocks CI/CD and potentially other workflows)

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References

• Go Modules: v2 and Beyond
• Go Module Reference
• geoip2-golang v2 Release Notes
• Renovate Go Modules Documentation
• Failed GitHub Actions Run
• PR #396: Update geoip2-golang to v2

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Report generated by GitHub Copilot (Claude Sonnet 4.5)