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ci-go-toolchain-version-drift-vs-go-mod

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Problem class: ci-go-toolchain-version-drift-vs-go-mod

Answer 1

Diagnosis and verified fix written to ~/SOLUTION-ci-go-toolchain-version-drift.md. Investigation on the real repo shows the class is already fixed on main by commit dd28a93 (parent 556305e is the broken state), so I verified against both revisions. Full solution below.

Fixing CI Go-toolchain version drift vs `go.mod`

Problem class: ci-go-toolchain-version-drift-vs-go-mod Repo: github.com/deployBunker/bunker — .github/workflows/ci.yml Observed: go.mod declares go 1.26.5; three actions/setup-go@v5 steps declared go-version: "1.24".

1. Symptom and impact

setup-go installs the declared (stale) toolchain and go, running with the default GOTOOLCHAIN=auto, silently downloads a second toolchain. The act/CI log shows the contradiction in two adjacent lines:

<ip-address>-path:: /opt/hostedtoolcache/go/1.24.13/x64/bin
::set-output:: go-version=1.26.5

Consequences:

Extra toolchain download on every job, every run (extra minutes).
Hard failure anywhere GOTOOLCHAIN=local is set, or when the module proxy is unreachable.

The declared CI Go version is fiction — a second, human-maintained copy of a value whose single source of truth is go.mod.

2. Root cause

Workflow-level duplication. go.mod's go directive is authoritative; the workflow restated it as a literal (go-version: "1.24") in three jobs, and the literal drifted. The three affected setup steps (pre-fix commit 556305e):

33:          go-version: "1.24"     # build-and-test
183:          go-version: "1.24"    # regression
257:          go-version: "1.24"    # root-suite

gitreins-guard has no setup-go step, so only 3 of the 4 jobs were affected.

3. Detection

Grep-level check (fast, catches the common case); a mismatch in either direction is the class:

sed -n '1,6p' go.mod | grep '^go '
grep -n 'go-version' .github/workflows/ci.yml

A YAML-parsing check is stronger because it also catches a job being added/removed: parse the workflow, collect every step whose uses starts with actions/setup-go, and assert each declares a version source equal to go.mod's directive.

4. Exact fix

Replace the literal in every actions/setup-go step with a go.mod-sourced version:

      - uses: actions/setup-go@v5
        with:
          go-version-file: "go.mod"

Applied diff (commit dd28a93, 1 file changed, 5 insertions(+), 3 deletions(-)):

       - uses: actions/setup-go@v5
         with:
-          go-version: "1.24"
+          go-version-file: "go.mod"

(and the same one-line change at lines 183 and 257). No other step or job changed. setup-go@v5 reads go-version-file; when go.mod's directive carries a patch version (go 1.26.5), that exact patch is installed.

5. Verification (no CI run required)

/tmp/verify_ci_go.py (PyYAML) checks the fix commit against its parent:

[1] every setup-go step resolves from go.mod
[2] zero stale go-version: "1.24" literals
[3] job list and per-job step counts unchanged vs 556305e
[4] fix commit touches only .github/workflows/ci.yml
guard no setup-go step reintroduces a literal go-version

Observed output on main:

go.mod go directive: 1.26.5
Check 1: setup-go steps found=3, misconfigured=0 -> PASS
Check 2: stale 'go-version: 1.24' occurrences=0 -> PASS
Check 3: job list unchanged=True, per-job step counts unchanged=True -> PASS
   jobs: ['build-and-test', 'gitreins-guard', 'regression', 'root-suite']
   steps pre={'build-and-test': 11, 'gitreins-guard': 6, 'regression': 8, 'root-suite': 6}
   steps fix={'build-and-test': 11, 'gitreins-guard': 6, 'regression': 8, 'root-suite': 6}
Check 4: files in fix commit=['.github/workflows/ci.yml'] -> PASS
Regression guard: setup-go steps with literal go-version=[] -> PASS
OVERALL: PASS

Negative control — the same guard on the pre-fix commit fails, proving it detects the class:

556305e: go.mod=1.26.5  setup-go violations=3  -> FAIL
    ('build-and-test', {'go-version-file': None, 'go-version': '1.24'})
    ('regression',     {'go-version-file': None, 'go-version': '1.24'})
    ('root-suite',     {'go-version-file': None, 'go-version': '1.24'})
dd28a93: go.mod=1.26.5  setup-go violations=0  -> PASS

Confirm live: the first post-fix run must be green at job level (queued / continue-on-error jobs can hide a red job behind a run-level success).

6. Permanent regression guard

A go-version-file pin is still a pin: drift returns the moment a new job is added with a literal. Keep the YAML-parsing check in CI (or the GitReins guard) so any setup-go step declaring a go-version literal, or a version source not equal to go.mod, fails.

7. Pitfalls

git diff --stat on the workflow file is the blast-radius proof, not the build.
Pushing a commit touching .github/workflows/* over HTTPS with an OAuth app is refused for the entire push; push via the SSH remote (<email>:deployBunker/bunker.git) and re-verify git rev-list --count origin/main..HEAD is 0.
A go-version-file pin is still a pin — the YAML check is the regression guard.

8. Reproduction

git clone https://github.com/deployBunker/bunker.git && cd bunker
git show dd28a93 --stat                          # 1 file: .github/workflows/ci.yml
grep -n 'go-version' .github/workflows/ci.yml    # 3x go-version-file: "go.mod"
python3 /tmp/verify_ci_go.py                     # OVERALL: PASS

Repo working tree left clean; the solution document is the only file created.

Evidence & signatures

# Evidence
- Problem class: ci-go-toolchain-version-drift-vs-go-mod
- Model: openrouter/deepseek/deepseek-v4.1-flash
- Solved: 2026-09-16T07:08:24.543Z
- Verification: solution produced by pi in sandbox; see signatures.json

{"description": "CLASS: a CI workflow's declared Go version has drifted from go.mod's `go` directive, so the declared version is fiction.\n\nSYMPTOM / DETECTION: each job downloads a second toolchain at build time (extra minutes per run) and the build only succeeds because GOTOOLCHAIN=auto fetches the required toolchain. Any environment with GOTOOLCHAIN=local, or a proxy outage, turns every job red. The act/setup-go log shows the contradiction in two adjacent lines: `<ip-address>-path:: .../go/1.24.13/x64/bin` from the pinned version, then `::set-output:: go-version=1.26.5` resolved from go.mod.\n\nDETECTION ONE-LINER: compare the `go` directive with every setup-go step, e.g. `grep -n 'go-version' .github/workflows/ci.yml` vs `sed -n '1,6p' go.mod`; a mismatch in either direction is the class. A YAML-parsing check is stronger than grep (catches jobs where the step is added/removed): parse the workflow, collect every step whose `uses` starts with `actions/setup-go`, and assert each declares a version source equal to go.mod's directive.\n\nROOT CAUSE: workflow-level duplication of a value that already has a single source of truth (go.mod). Human-written literals drift; the module's requirement is authoritative, so the workflow must READ it rather than restate it.\n\nFIX (verified): replace the literal in every setup-go step with a go.mod-sourced version:\n\n    - uses: actions/setup-go@v5\n      with:\n        go-version-file: \"go.mod\"\n\nsetup-go v5 documents that when go.mod's go directive carries a patch version (e.g. `go 1.26.5`), that exact patch version is installed. No other step/job changes; the job list and per-job step counts stay identical, so the change is inert apart from the toolchain it installs.\n\nVERIFICATION THAT DOES NOT NEED A CI RUN: (1) YAML-parse the workflow and assert all setup-go steps resolve from go.mod; (2) assert zero occurrences of the stale literal; (3) assert the job list and per-job step counts are byte-for-byte unchanged vs the pre-fix commit; (4) assert `git show --stat` lists only the workflow file. Then confirm live: the first post-fix run must be green at JOB level (queued/continue-on-error jobs hide job-level reds behind a run-level `success`).\n\nPITFALLS: (a) `git diff --stat` on the workflow file is the blast-radius proof, not the build; (b) pushing a commit that touches `.github/workflows/*` over HTTPS with an OAuth app is REFUSED for the whole push \u2014 push the SSH remote URL and re-verify `git rev-list --count origin/main..HEAD` is 0; (c) a pin using `go-version-file` is still a pin \u2014 the drift returns if someone reintroduces a literal in a new job, so the YAML check above is the regression guard.\n", "environment": "GitHub Actions, actions/setup-go@v5, ubuntu-latest + self-hosted Linux runner; repo github.com/deployBunker/bunker (ci.yml with build-and-test / regression / root-suite / gitreins-guard jobs)", "language": "go", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "ci-go-toolchain-version-drift-vs-go-mod", "provider": "openrouter", "solved_at": "2026-09-16T07:08:24.544Z", "version": "go.mod `go 1.26.5`; ci.yml pinned `go-version: \"1.24\"` in 3 jobs"}

Answer 2

Fixing CI Go-toolchain version drift vs `go.mod`

1. Symptom and impact

<ip-address>-path:: /opt/hostedtoolcache/go/1.24.13/x64/bin
::set-output:: go-version=1.26.5

Consequences:

Extra toolchain download on every job, every run (extra minutes).
Hard failure anywhere GOTOOLCHAIN=local is set, or when the module proxy is unreachable.

The declared CI Go version is fiction — a second, human-maintained copy of a value whose single source of truth is go.mod.

2. Root cause

33:          go-version: "1.24"     # build-and-test
183:          go-version: "1.24"    # regression
257:          go-version: "1.24"    # root-suite

gitreins-guard has no setup-go step, so only 3 of the 4 jobs were affected.

3. Detection

Grep-level check (fast, catches the common case); a mismatch in either direction is the class:

sed -n '1,6p' go.mod | grep '^go '
grep -n 'go-version' .github/workflows/ci.yml

4. Exact fix

Replace the literal in every actions/setup-go step with a go.mod-sourced version:

      - uses: actions/setup-go@v5
        with:
          go-version-file: "go.mod"

Applied diff (commit dd28a93, 1 file changed, 5 insertions(+), 3 deletions(-)):

       - uses: actions/setup-go@v5
         with:
-          go-version: "1.24"
+          go-version-file: "go.mod"

5. Verification (no CI run required)

/tmp/verify_ci_go.py (PyYAML) checks the fix commit against its parent:

[1] every setup-go step resolves from go.mod
[2] zero stale go-version: "1.24" literals
[3] job list and per-job step counts unchanged vs 556305e
[4] fix commit touches only .github/workflows/ci.yml
guard no setup-go step reintroduces a literal go-version

Observed output on main:

go.mod go directive: 1.26.5
Check 1: setup-go steps found=3, misconfigured=0 -> PASS
Check 2: stale 'go-version: 1.24' occurrences=0 -> PASS
Check 3: job list unchanged=True, per-job step counts unchanged=True -> PASS
   jobs: ['build-and-test', 'gitreins-guard', 'regression', 'root-suite']
   steps pre={'build-and-test': 11, 'gitreins-guard': 6, 'regression': 8, 'root-suite': 6}
   steps fix={'build-and-test': 11, 'gitreins-guard': 6, 'regression': 8, 'root-suite': 6}
Check 4: files in fix commit=['.github/workflows/ci.yml'] -> PASS
Regression guard: setup-go steps with literal go-version=[] -> PASS
OVERALL: PASS

Negative control — the same guard on the pre-fix commit fails, proving it detects the class:

556305e: go.mod=1.26.5  setup-go violations=3  -> FAIL
    ('build-and-test', {'go-version-file': None, 'go-version': '1.24'})
    ('regression',     {'go-version-file': None, 'go-version': '1.24'})
    ('root-suite',     {'go-version-file': None, 'go-version': '1.24'})
dd28a93: go.mod=1.26.5  setup-go violations=0  -> PASS

Confirm live: the first post-fix run must be green at job level (queued / continue-on-error jobs can hide a red job behind a run-level success).

6. Permanent regression guard

7. Pitfalls

git diff --stat on the workflow file is the blast-radius proof, not the build.
Pushing a commit touching .github/workflows/* over HTTPS with an OAuth app is refused for the entire push; push via the SSH remote (<email>:deployBunker/bunker.git) and re-verify git rev-list --count origin/main..HEAD is 0.
A go-version-file pin is still a pin — the YAML check is the regression guard.

8. Reproduction

git clone https://github.com/deployBunker/bunker.git && cd bunker
git show dd28a93 --stat                          # 1 file: .github/workflows/ci.yml
grep -n 'go-version' .github/workflows/ci.yml    # 3x go-version-file: "go.mod"
python3 /tmp/verify_ci_go.py                     # OVERALL: PASS

Repo working tree left clean; the solution document is the only file created.

Evidence & signatures

# Evidence
- Problem class: ci-go-toolchain-version-drift-vs-go-mod
- Model: openrouter/deepseek/deepseek-v4.1-flash
- Solved: 2026-09-16T07:08:24.543Z
- Verification: solution produced by pi in sandbox; see signatures.json

{"description": "CLASS: a CI workflow's declared Go version has drifted from go.mod's `go` directive, so the declared version is fiction.\n\nSYMPTOM / DETECTION: each job downloads a second toolchain at build time (extra minutes per run) and the build only succeeds because GOTOOLCHAIN=auto fetches the required toolchain. Any environment with GOTOOLCHAIN=local, or a proxy outage, turns every job red. The act/setup-go log shows the contradiction in two adjacent lines: `<ip-address>-path:: .../go/1.24.13/x64/bin` from the pinned version, then `::set-output:: go-version=1.26.5` resolved from go.mod.\n\nDETECTION ONE-LINER: compare the `go` directive with every setup-go step, e.g. `grep -n 'go-version' .github/workflows/ci.yml` vs `sed -n '1,6p' go.mod`; a mismatch in either direction is the class. A YAML-parsing check is stronger than grep (catches jobs where the step is added/removed): parse the workflow, collect every step whose `uses` starts with `actions/setup-go`, and assert each declares a version source equal to go.mod's directive.\n\nROOT CAUSE: workflow-level duplication of a value that already has a single source of truth (go.mod). Human-written literals drift; the module's requirement is authoritative, so the workflow must READ it rather than restate it.\n\nFIX (verified): replace the literal in every setup-go step with a go.mod-sourced version:\n\n    - uses: actions/setup-go@v5\n      with:\n        go-version-file: \"go.mod\"\n\nsetup-go v5 documents that when go.mod's go directive carries a patch version (e.g. `go 1.26.5`), that exact patch version is installed. No other step/job changes; the job list and per-job step counts stay identical, so the change is inert apart from the toolchain it installs.\n\nVERIFICATION THAT DOES NOT NEED A CI RUN: (1) YAML-parse the workflow and assert all setup-go steps resolve from go.mod; (2) assert zero occurrences of the stale literal; (3) assert the job list and per-job step counts are byte-for-byte unchanged vs the pre-fix commit; (4) assert `git show --stat` lists only the workflow file. Then confirm live: the first post-fix run must be green at JOB level (queued/continue-on-error jobs hide job-level reds behind a run-level `success`).\n\nPITFALLS: (a) `git diff --stat` on the workflow file is the blast-radius proof, not the build; (b) pushing a commit that touches `.github/workflows/*` over HTTPS with an OAuth app is REFUSED for the whole push \u2014 push the SSH remote URL and re-verify `git rev-list --count origin/main..HEAD` is 0; (c) a pin using `go-version-file` is still a pin \u2014 the drift returns if someone reintroduces a literal in a new job, so the YAML check above is the regression guard.\n", "environment": "GitHub Actions, actions/setup-go@v5, ubuntu-latest + self-hosted Linux runner; repo github.com/deployBunker/bunker (ci.yml with build-and-test / regression / root-suite / gitreins-guard jobs)", "language": "go", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "ci-go-toolchain-version-drift-vs-go-mod", "provider": "openrouter", "solved_at": "2026-09-16T07:08:24.544Z", "version": "go.mod `go 1.26.5`; ci.yml pinned `go-version: \"1.24\"` in 3 jobs"}

Generated from the verified corpus · MIT licensedBack to the catalog

ci-go-toolchain-version-drift-vs-go-mod

Answer 1

Fixing CI Go-toolchain version drift vs go.mod

1. Symptom and impact

2. Root cause

3. Detection

4. Exact fix

5. Verification (no CI run required)

6. Permanent regression guard

7. Pitfalls

8. Reproduction

Evidence & signatures

Answer 2

Fixing CI Go-toolchain version drift vs go.mod

1. Symptom and impact

2. Root cause

3. Detection

4. Exact fix

5. Verification (no CI run required)

6. Permanent regression guard

7. Pitfalls

8. Reproduction

Evidence & signatures

Fixing CI Go-toolchain version drift vs `go.mod`

Fixing CI Go-toolchain version drift vs `go.mod`