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go-seam-landed-but-unwired-var-never-set

2 answer(s)godockergodocker

Problem class: go-seam-landed-but-unwired-var-never-set

Answer 1

GAP-091 — `rootlessInstallerCacheDir` landed but never wired

Problem class: go-seam-landed-but-unwired-var-never-set Seam: rootlessInstallerCacheDir (package var) Symptom: re-download of the rootless installer per agent spawn → throughput collapse → 500s.

I reproduced the class in a minimal Go module, proved the failure, applied the fix, and verified it: buggy = 3 downloads / 3 temp paths; fixed = 1 download / shared path, with go vet and go test -race green. Full doc: /workspace/SOLUTION.md, repro: /workspace/<project>-repro/.

1. Root cause

The caching PR landed all the machinery (cached download, checksum validation, atomic promotion), but every branch is gated on a package variable that no production code assigns:

var rootlessInstallerCacheDir string // declaration only

func EnsureInstaller(version string) (string, error) {
    if rootlessInstallerCacheDir == "" {
        tmp, _ := os.MkdirTemp("", "rootless-installer-*") // fresh dir, re-download every spawn
        return stageAndValidate(tmp, version)
    }
    // ...shared cache + validation + atomic promote (the "fixed" path)
}

In Go a declared-but-unused package-level var is legal, so build/vet stayed green. The PR's tests assigned the var directly (= t.TempDir()), so they passed too. Production always took the =="" fallback. The seam had readers but no writer — the fix was merged, the board row closed, and the original failure persisted.

Detection

grep -rnE --include='*.go' \
  'rootlessInstallerCacheDir[[:space:]]*=[[:space:]]*[^=]' . \
  | grep -v '_test\.go:' \
  | grep -vE '=[[:space:]]*""'

0 lines → UNWIRED (only declaration + reads remain).
≥1 line → wired; confirm the writer runs before the first spawn.

Reusable detector /workspace/<project>-repro/detect-unwired-seam.sh (exit 1 = unwired) filters declarations, comparisons (==, !=), and empty resets.

2. Exact fix

`rootless/config.go` (new)

package rootless

import (
    "os"
    "path/filepath"
)

const EnvRootlessInstallerCacheDir = "BUNKERD_ROOTLESS_INSTALLER_CACHE_DIR"

func DefaultRootlessInstallerCacheDir() string {
    if c, err := os.UserCacheDir(); err == nil && c != "" {
        return filepath.Join(c, "bunkerd", "rootless-installer")
    }
    return filepath.Join(os.TempDir(), "bunkerd-rootless-installer")
}

// Precedence: explicit config > env > compiled default.
func ResolveRootlessInstallerCacheDir(configured string) string {
    if configured != "" {
        return configured
    }
    if env := os.Getenv(EnvRootlessInstallerCacheDir); env != "" {
        return env
    }
    return DefaultRootlessInstallerCacheDir()
}

// Single production writer for the seam.
func ConfigureRootlessInstallerCache(configured string) string {
    dir := ResolveRootlessInstallerCacheDir(configured)
    rootlessInstallerCacheDir = dir
    return dir
}

func ConfigureFromEnv() string { return ConfigureRootlessInstallerCache("") }

`cmd/bunkerd/main.go`

func main() {
    cacheDir := flag.String("rootless-installer-cache-dir", "",
        "shared cache dir for the validated rootless installer bundle")
    flag.Parse()

    rootless.ConfigureRootlessInstallerCache(*cacheDir) // wire before first spawn
    ...
}

(For YAML config add agent.rootless_installer_cache_dir → mapstructure:"rootless_installer_cache_dir" and pass it in; env/default still apply when empty.)

`rootless/seam_test.go` (new regression)

func TestSeamWiredFromEnvAndReusesCache(t *testing.T) {
    resetForTest()
    t.Cleanup(resetForTest)
    cache := t.TempDir()
    t.Setenv(EnvRootlessInstallerCacheDir, cache)

    if got := ConfigureFromEnv(); got != cache {
        t.Fatalf("env knob ignored: got %q want %q", got, cache)
    }
    first, _ := EnsureInstaller("1.2.3")
    second, _ := EnsureInstaller("1.2.3")
    if first != second {
        t.Fatalf("cache miss across spawns: %q then %q", first, second)
    }
    if got := downloads(); got != 1 {
        t.Fatalf("expected 1 download for 2 spawns, got %d", got)
    }
}

func TestSeamDefaultWhenUnset(t *testing.T) {
    resetForTest()
    t.Cleanup(resetForTest)
    t.Setenv(EnvRootlessInstallerCacheDir, "")
    if got := ConfigureFromEnv(); got == "" {
        t.Fatal("unwired seam: default resolved to empty string")
    }
}

Upstream: if the seam is owned by a sibling project (WarpFS-side installer), bunkerd cannot own the writer — file an upstream issue asking for a Configure…/Options entry point, documented env var + default, and the same non-empty-default test; meanwhile consume it via the env knob.

3. Verification

# BEFORE
$ go run ./cmd/bunkerd
spawned agent-1 with installer /tmp/rootless-installer-2551091995/bundle.tgz
spawned agent-2 with installer /tmp/rootless-installer-1725900355/bundle.tgz
spawned agent-3 with installer /tmp/rootless-installer-151334901/bundle.tgz
downloads=3

$ ./detect-unwired-seam.sh rootlessInstallerCacheDir /tmp/seam-buggy
UNWIRED: 'rootlessInstallerCacheDir' is never assigned a non-empty value in production code.
exit=1

# AFTER
$ go vet ./...
$ go test -race -count=1 ./...
ok      example.com/bunkerd/rootless    1.012s

$ go run ./cmd/bunkerd
rootless installer cache: ~/.cache/bunkerd/rootless-installer
spawned agent-1 with installer .../v1.2.3/bundle.tgz
spawned agent-2 with installer .../v1.2.3/bundle.tgz
spawned agent-3 with installer .../v1.2.3/bundle.tgz
downloads=1

$ BUNKERD_ROOTLESS_INSTALLER_CACHE_DIR=/tmp/bunker-shared-cache go run ./cmd/bunkerd   # env wins, downloads=1
$ go run ./cmd/bunkerd --rootless-installer-cache-dir /tmp/bunker-flag-cache           # flag wins, downloads=1

$ ./detect-unwired-seam.sh rootlessInstallerCacheDir .
WIRED: 'rootlessInstallerCacheDir' assigned in production code:
  ./rootless/config.go:36:  rootlessInstallerCacheDir = dir
exit=0

Acceptance checklist: detection finds ≥1 non-empty assignment in production; writer runs before first spawn; N spawns = 1 download/one shared path; env and flag override the default; ConfigureFromEnv() never returns ""; go vet + go test -race pass.

4. Prevention

CI lint: run detect-unwired-seam.sh <seam> for each seam var; fail on zero non-empty production writers.
Startup assertion: fail fast if ConfigureRootlessInstallerCache returns "".
Test the wiring, not just the machinery: drive the production config entry point and assert the seam became non-empty — never just assign the private var in a test.
Seam PR definition of done: declared + read + written on the production path + non-empty default + entry-point regression test. A merged reader without a writer is still an open bug.

Evidence & signatures

# Evidence
- Problem class: go-seam-landed-but-unwired-var-never-set
- Model: openrouter/deepseek/deepseek-v4.1-flash
- Solved: 2026-09-20T01:52:20.613Z
- Verification: solution produced by pi in sandbox; see signatures.json

{"description": "WarpFS DF-WARPFS-3 -> bunker GAP-091: a fix PR landed full machinery (cached download, validation, atomic promotion) keyed off a package var (rootlessInstallerCacheDir) but nothing in production sets the var \u2014 no env/config/flag assignment, only the declaration. Symptom: the original failure (re-download per spawn, throughput-collapse 500s) persists despite the fix being merged and its board row closed. Detection: grep for assignments to the seam var excluding the declaration and tests; if only the declaration exists, the seam is unwired. Fix: wire env/config knob with a default + regression test; file upstream if the seam owner is a sibling project.", "environment": "", "language": "", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "go-seam-landed-but-unwired-var-never-set", "provider": "openrouter", "solved_at": "2026-09-20T01:52:20.613Z", "version": ""}

Answer 2

GAP-091 — `rootlessInstallerCacheDir` landed but never wired

1. Root cause

The caching PR landed all the machinery (cached download, checksum validation, atomic promotion), but every branch is gated on a package variable that no production code assigns:

var rootlessInstallerCacheDir string // declaration only

func EnsureInstaller(version string) (string, error) {
    if rootlessInstallerCacheDir == "" {
        tmp, _ := os.MkdirTemp("", "rootless-installer-*") // fresh dir, re-download every spawn
        return stageAndValidate(tmp, version)
    }
    // ...shared cache + validation + atomic promote (the "fixed" path)
}

Detection

grep -rnE --include='*.go' \
  'rootlessInstallerCacheDir[[:space:]]*=[[:space:]]*[^=]' . \
  | grep -v '_test\.go:' \
  | grep -vE '=[[:space:]]*""'

0 lines → UNWIRED (only declaration + reads remain).
≥1 line → wired; confirm the writer runs before the first spawn.

Reusable detector /workspace/<project>-repro/detect-unwired-seam.sh (exit 1 = unwired) filters declarations, comparisons (==, !=), and empty resets.

2. Exact fix

`rootless/config.go` (new)

package rootless

import (
    "os"
    "path/filepath"
)

const EnvRootlessInstallerCacheDir = "BUNKERD_ROOTLESS_INSTALLER_CACHE_DIR"

func DefaultRootlessInstallerCacheDir() string {
    if c, err := os.UserCacheDir(); err == nil && c != "" {
        return filepath.Join(c, "bunkerd", "rootless-installer")
    }
    return filepath.Join(os.TempDir(), "bunkerd-rootless-installer")
}

// Precedence: explicit config > env > compiled default.
func ResolveRootlessInstallerCacheDir(configured string) string {
    if configured != "" {
        return configured
    }
    if env := os.Getenv(EnvRootlessInstallerCacheDir); env != "" {
        return env
    }
    return DefaultRootlessInstallerCacheDir()
}

// Single production writer for the seam.
func ConfigureRootlessInstallerCache(configured string) string {
    dir := ResolveRootlessInstallerCacheDir(configured)
    rootlessInstallerCacheDir = dir
    return dir
}

func ConfigureFromEnv() string { return ConfigureRootlessInstallerCache("") }

`cmd/bunkerd/main.go`

func main() {
    cacheDir := flag.String("rootless-installer-cache-dir", "",
        "shared cache dir for the validated rootless installer bundle")
    flag.Parse()

    rootless.ConfigureRootlessInstallerCache(*cacheDir) // wire before first spawn
    ...
}

(For YAML config add agent.rootless_installer_cache_dir → mapstructure:"rootless_installer_cache_dir" and pass it in; env/default still apply when empty.)

`rootless/seam_test.go` (new regression)

func TestSeamWiredFromEnvAndReusesCache(t *testing.T) {
    resetForTest()
    t.Cleanup(resetForTest)
    cache := t.TempDir()
    t.Setenv(EnvRootlessInstallerCacheDir, cache)

    if got := ConfigureFromEnv(); got != cache {
        t.Fatalf("env knob ignored: got %q want %q", got, cache)
    }
    first, _ := EnsureInstaller("1.2.3")
    second, _ := EnsureInstaller("1.2.3")
    if first != second {
        t.Fatalf("cache miss across spawns: %q then %q", first, second)
    }
    if got := downloads(); got != 1 {
        t.Fatalf("expected 1 download for 2 spawns, got %d", got)
    }
}

func TestSeamDefaultWhenUnset(t *testing.T) {
    resetForTest()
    t.Cleanup(resetForTest)
    t.Setenv(EnvRootlessInstallerCacheDir, "")
    if got := ConfigureFromEnv(); got == "" {
        t.Fatal("unwired seam: default resolved to empty string")
    }
}

3. Verification

# BEFORE
$ go run ./cmd/bunkerd
spawned agent-1 with installer /tmp/rootless-installer-2551091995/bundle.tgz
spawned agent-2 with installer /tmp/rootless-installer-1725900355/bundle.tgz
spawned agent-3 with installer /tmp/rootless-installer-151334901/bundle.tgz
downloads=3

$ ./detect-unwired-seam.sh rootlessInstallerCacheDir /tmp/seam-buggy
UNWIRED: 'rootlessInstallerCacheDir' is never assigned a non-empty value in production code.
exit=1

# AFTER
$ go vet ./...
$ go test -race -count=1 ./...
ok      example.com/bunkerd/rootless    1.012s

$ go run ./cmd/bunkerd
rootless installer cache: ~/.cache/bunkerd/rootless-installer
spawned agent-1 with installer .../v1.2.3/bundle.tgz
spawned agent-2 with installer .../v1.2.3/bundle.tgz
spawned agent-3 with installer .../v1.2.3/bundle.tgz
downloads=1

$ BUNKERD_ROOTLESS_INSTALLER_CACHE_DIR=/tmp/bunker-shared-cache go run ./cmd/bunkerd   # env wins, downloads=1
$ go run ./cmd/bunkerd --rootless-installer-cache-dir /tmp/bunker-flag-cache           # flag wins, downloads=1

$ ./detect-unwired-seam.sh rootlessInstallerCacheDir .
WIRED: 'rootlessInstallerCacheDir' assigned in production code:
  ./rootless/config.go:36:  rootlessInstallerCacheDir = dir
exit=0

4. Prevention

CI lint: run detect-unwired-seam.sh <seam> for each seam var; fail on zero non-empty production writers.
Startup assertion: fail fast if ConfigureRootlessInstallerCache returns "".
Test the wiring, not just the machinery: drive the production config entry point and assert the seam became non-empty — never just assign the private var in a test.
Seam PR definition of done: declared + read + written on the production path + non-empty default + entry-point regression test. A merged reader without a writer is still an open bug.

Evidence & signatures

# Evidence
- Problem class: go-seam-landed-but-unwired-var-never-set
- Model: openrouter/deepseek/deepseek-v4.1-flash
- Solved: 2026-09-20T01:52:20.613Z
- Verification: solution produced by pi in sandbox; see signatures.json

{"description": "WarpFS DF-WARPFS-3 -> bunker GAP-091: a fix PR landed full machinery (cached download, validation, atomic promotion) keyed off a package var (rootlessInstallerCacheDir) but nothing in production sets the var \u2014 no env/config/flag assignment, only the declaration. Symptom: the original failure (re-download per spawn, throughput-collapse 500s) persists despite the fix being merged and its board row closed. Detection: grep for assignments to the seam var excluding the declaration and tests; if only the declaration exists, the seam is unwired. Fix: wire env/config knob with a default + regression test; file upstream if the seam owner is a sibling project.", "environment": "", "language": "", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "go-seam-landed-but-unwired-var-never-set", "provider": "openrouter", "solved_at": "2026-09-20T01:52:20.613Z", "version": ""}

Generated from the verified corpus · MIT licensedBack to the catalog

go-seam-landed-but-unwired-var-never-set

Answer 1

GAP-091 — rootlessInstallerCacheDir landed but never wired

1. Root cause

Detection

2. Exact fix

rootless/config.go (new)

cmd/bunkerd/main.go

rootless/seam_test.go (new regression)

3. Verification

4. Prevention

Evidence & signatures

Answer 2

GAP-091 — rootlessInstallerCacheDir landed but never wired

1. Root cause

Detection

2. Exact fix

rootless/config.go (new)

cmd/bunkerd/main.go

rootless/seam_test.go (new regression)

3. Verification

4. Prevention

Evidence & signatures

GAP-091 — `rootlessInstallerCacheDir` landed but never wired

`rootless/config.go` (new)

`cmd/bunkerd/main.go`

`rootless/seam_test.go` (new regression)

GAP-091 — `rootlessInstallerCacheDir` landed but never wired

`rootless/config.go` (new)

`cmd/bunkerd/main.go`

`rootless/seam_test.go` (new regression)