Makefile Validator Skill

Makefile Validator

Overview

Use this skill to validate Makefiles with a local-first, deterministic flow.

Default validator entrypoint:

bash scripts/validate_makefile.sh <makefile-path>

Validation layers:

Dependency preflight (python3, pip3, make)
GNU make syntax check (make -n --dry-run) when make is available
mbake validate
mbake format --check
Custom security, best-practice, and optimization checks
Optional checkmake and unmake checks when installed

Trigger Guidance

Use this skill when the request includes Makefile quality, linting, validation, hardening, or troubleshooting.

Trigger Phrases

"Validate this Makefile"
"Lint my .mk file"
"Find issues in this build Makefile"
"Check Makefile security problems"
"Review this Makefile before CI"

Non-Trigger Examples

Creating a brand new Makefile from scratch (use makefile-generator)
Running build targets as part of delivery
General shell scripting work unrelated to Makefiles

Deterministic Execution Model

Run from this skill directory for shortest commands:

cd devops-skills-plugin/skills/makefile-validator

Step 1: Preflight

Confirm target file exists and is readable.
Confirm whether file edits are allowed (writable) or only suggestions can be returned (read-only).
Prefer the default validator path first; use fallbacks only when blocked by environment constraints.

Step 2: Baseline Validation (Default Path)

# From skill directory
bash scripts/validate_makefile.sh <makefile-path>

# From repository root
bash devops-skills-plugin/skills/makefile-validator/scripts/validate_makefile.sh <makefile-path>

Always record:

command executed
exit code
summary counts (Errors, Warnings, Info)
issue locations reported by tools

Step 3: Interpret Output and Exit Code

| Exit code | Meaning | Expected summary line | Action | | --- | --- | --- | --- | | 0 | no blocking findings | Validation PASSED | optional improvements only | | 1 | warning-only result | Validation PASSED with warnings | fix recommended; merge policy dependent | | 2 | error result | Validation FAILED - errors must be fixed | fix required, then rerun |

Step 4: Progressive Reference Loading

Open only the docs required by the current findings.

| Finding type | Reference doc | | --- | --- | | .PHONY, .DELETE_ON_ERROR, .ONESHELL, variable usage, performance structure | docs/best-practices.md | | tabs vs spaces, dependency mistakes, credential patterns, anti-patterns | docs/common-mistakes.md | | mbake behavior, formatter flags, known mbake caveats | docs/bake-tool.md |

Step 5: Fix + Rerun Loop

After applying fixes, rerun:

bash scripts/validate_makefile.sh <makefile-path>

Loop rules:

Stop only when no new errors are introduced.
If warnings remain intentionally, document why they are accepted.
Always report the latest rerun exit code.

How to Open Docs

Use explicit file-open commands so paths are unambiguous.

From repository root:

sed -n '1,220p' devops-skills-plugin/skills/makefile-validator/docs/best-practices.md
sed -n '1,220p' devops-skills-plugin/skills/makefile-validator/docs/common-mistakes.md
sed -n '1,220p' devops-skills-plugin/skills/makefile-validator/docs/bake-tool.md
rg -n "PHONY|DELETE_ON_ERROR|ONESHELL|tab|credential|mbake" devops-skills-plugin/skills/makefile-validator/docs/*.md

From devops-skills-plugin/skills/makefile-validator:

sed -n '1,220p' docs/best-practices.md
sed -n '1,220p' docs/common-mistakes.md
sed -n '1,220p' docs/bake-tool.md
rg -n "PHONY|DELETE_ON_ERROR|ONESHELL|tab|credential|mbake" docs/*.md

If shell commands are unavailable, use the environment's file-open/read actions on the same paths.

Fallback Behavior

Use these only when the default validator path cannot run fully.

| Constraint | Fallback action | Reporting requirement | | --- | --- | --- | | python3 or pip3 unavailable | Run limited checks (make -f <file> -n --dry-run if make exists, plus focused grep checks) | State that mbake stages were skipped and coverage is reduced | | pip3 install mbake fails (offline/proxy/index issue) | Keep syntax/custom checks that still work; defer formatter/linter stages | Report install failure and request rerun in a network-enabled environment | | make unavailable | Continue with non-syntax stages; script already downgrades syntax stage | Explicitly note syntax coverage was skipped | | checkmake or unmake unavailable | Continue; these are optional stages | Note optional lint/portability coverage not executed | | target file is read-only | Provide patch suggestions only | Mark response as advisory only | | command execution unavailable | Provide static review from file contents and docs | Mark result as non-executed analysis |

Minimal fallback commands:

# Syntax only (when make exists)
make -f <makefile-path> -n --dry-run

# Focused quick checks
grep -n "^\\.DELETE_ON_ERROR:" <makefile-path>
grep -n "^\\.PHONY:" <makefile-path>
grep -nE "^(  |    |        )[a-zA-Z@\\$\\(]" <makefile-path>

Example Outcomes Mapped to Exit Codes

Clean Result (`exit 0`)

Errors:   0
Warnings: 0
Info:     2
✓ Validation PASSED

Warning-Only Result (`exit 1`)

Errors:   0
Warnings: 3
Info:     1
⚠ Validation PASSED with warnings

Error Result (`exit 2`)

Errors:   2
Warnings: 1
Info:     0
⚠ Validation FAILED - errors must be fixed

Troubleshooting Quick Start

Verify required tools:

command -v python3 pip3 make

Isolate GNU make syntax failures:

make -f <makefile-path> -n --dry-run

Check likely tab-indentation violations:

grep -nE "^(  |    |        )[a-zA-Z@\\$\\(]" <makefile-path>

Rerun validator with plain output and capture log:

NO_COLOR=1 bash scripts/validate_makefile.sh <makefile-path> > /tmp/makefile-validator.log 2>&1
echo "exit=$? log=/tmp/makefile-validator.log"

If mbake install keeps failing, validate in a network-enabled shell or with an internal PyPI mirror, then rerun the full validator.

Skill Paths

makefile-validator/
├── SKILL.md
├── scripts/
│   └── validate_makefile.sh
├── docs/
│   ├── best-practices.md
│   ├── common-mistakes.md
│   └── bake-tool.md
└── examples/
    ├── good-makefile.mk
    └── bad-makefile.mk

Done Criteria

This skill update is complete when all are true:

Trigger guidance is explicit and easy to identify.
Execution flow is deterministic (preflight -> run -> interpret -> docs -> rerun).
"How to open docs" instructions include exact commands and paths.
Example outcomes are explicitly tied to exit codes (0, 1, 2).
Fallback behavior is documented for missing tools and constrained environments.
Troubleshooting quick-start is concise and runnable.
Frontmatter name and description remain unchanged.

Agent Skills: Makefile Validator

Install this agent skill to your local

Skill Files