Managing Megalinter

---
name: managing-megalinter
description: |
  Use when working with Megalinter — megaLinter multi-language linting
  management. Covers linter configuration, flavor selection, reporter setup, CI
  integration, and fix mode management. Use when managing MegaLinter
  configurations, enabling or disabling linters, debugging linter failures, or
  optimizing linting performance.
connection_type: megalinter
preload: false
---

# MegaLinter Multi-Language Linting Management Skill

Manage and analyze MegaLinter configurations, linter results, and CI integration.

## MANDATORY: Discovery-First Pattern

**Always check current MegaLinter configuration before modifying linter settings.**

### Phase 1: Discovery

```bash
#!/bin/bash

echo "=== MegaLinter Configuration ==="
cat .mega-linter.yml 2>/dev/null || cat .megalinter.yml 2>/dev/null || echo "No MegaLinter config found"

echo ""
echo "=== CI Integration ==="
grep -r 'mega-linter\|megalinter' .github/workflows/ 2>/dev/null | head -10

echo ""
echo "=== Flavor ==="
grep -E 'FLAVOR|image.*megalinter' .github/workflows/*.yml 2>/dev/null | head -5

echo ""
echo "=== Enabled/Disabled Linters ==="
grep -E 'ENABLE|DISABLE' .mega-linter.yml .megalinter.yml 2>/dev/null | head -10
```

### Phase 2: Analysis

```bash
#!/bin/bash

echo "=== Linter Configuration ==="
cat .mega-linter.yml 2>/dev/null | head -30

echo ""
echo "=== Reports ==="
ls -la megalinter-reports/ 2>/dev/null | head -10

echo ""
echo "=== Latest Results ==="
cat megalinter-reports/megalinter-report.json 2>/dev/null | jq '{
  total_linters: (.linters | length),
  success: [.linters[] | select(.status == "success")] | length,
  error: [.linters[] | select(.status == "error")] | length,
  errors_by_linter: [.linters[] | select(.status == "error") | .linter_name]
}' 2>/dev/null
```

## Output Rules
- **TOKEN EFFICIENCY**: Target <=50 lines per output
- Summarize linter results with pass/fail counts
- List failing linters with error counts
- Report flavor and active linter list

## Common Operations

### Run Locally

```bash
#!/bin/bash
echo "=== Local MegaLinter Run ==="
npx mega-linter-runner --fix 2>&1 | tail -20
```

### Linter Status

```bash
#!/bin/bash
echo "=== Available Linters ==="
cat megalinter-reports/megalinter-report.json 2>/dev/null | jq '[.linters[] | {
  name: .linter_name,
  language: .language,
  status: .status,
  files_count: .files_count
}] | sort_by(.status)' 2>/dev/null | head -30
```

## Safety Rules

- **Start with a curated flavor** rather than the full image to reduce CI time
- **Enable fix mode cautiously** -- auto-fixes can introduce unintended changes
- **Review linter disable lists** periodically for outdated exclusions
- **Test configuration changes** locally with `mega-linter-runner` before CI deployment

## Output Format

Present results as a structured report:
```
Managing Megalinter Report
══════════════════════════
Resources discovered: [count]

Resource       Status    Key Metric    Issues
──────────────────────────────────────────────
[name]         [ok/warn] [value]       [findings]

Summary: [total] resources | [ok] healthy | [warn] warnings | [crit] critical
Action Items: [list of prioritized findings]
```

Target ≤50 lines of output. Use tables for multi-resource comparisons.

## Anti-Hallucination Rules

1. **NEVER assume resource names** — always discover via CLI/API in Phase 1 before referencing in Phase 2.
2. **NEVER fabricate metric names or dimensions** — verify against the service documentation or `--help` output.
3. **NEVER mix CLI commands between service versions** — confirm which version/API you are targeting.
4. **ALWAYS use the discovery → verify → analyze chain** — every resource referenced must have been discovered first.
5. **ALWAYS handle empty results gracefully** — an empty response is valid data, not an error to retry.

## Counter-Rationalizations

| Shortcut | Counter | Why |
|----------|---------|-----|
| "I'll skip discovery and check known resources" | Always run Phase 1 discovery first | Resource names change, new resources appear — assumed names cause errors |
| "The user only asked for a quick check" | Follow the full discovery → analysis flow | Quick checks miss critical issues; structured analysis catches silent failures |
| "Default configuration is probably fine" | Audit configuration explicitly | Defaults often leave logging, security, and optimization features disabled |
| "Metrics aren't needed for this" | Always check relevant metrics when available | API/CLI responses show current state; metrics reveal trends and intermittent issues |
| "I don't have access to that" | Try the command and report the actual error | Assumed permission failures prevent useful investigation; actual errors are informative |