Metadata
- name
- webpack-config-validator
- description
- Validate JSON-exported webpack configuration files for structural issues, deprecated loaders/plugins, optimization gaps, and best practices. Use when auditing webpack configs, preparing production builds, or enforcing CI standards.
Webpack Config Validator
Validate webpack configuration files exported as JSON for structural correctness, entry/output issues, deprecated loaders and plugins, optimization configuration, and best practices. Pure Python 3 stdlib — no external dependencies.
Note: webpack configs are JS/TS, not directly parseable. This validator works with JSON-exported configs. Export via:
node -e "console.log(JSON.stringify(require('./webpack.config.js')))" > config.json
python3 scripts/webpack_config_validator.py validate config.json
Commands
validate — Full validation with all rules
python3 scripts/webpack_config_validator.py validate config.json
python3 scripts/webpack_config_validator.py validate config.json --strict
python3 scripts/webpack_config_validator.py validate config.json --format json --mode production
check — Quick check (errors and warnings only)
python3 scripts/webpack_config_validator.py check config.json
python3 scripts/webpack_config_validator.py check config.json --format summary
explain — Show all rules with descriptions
python3 scripts/webpack_config_validator.py explain config.json
python3 scripts/webpack_config_validator.py explain config.json --format json
suggest — Run validation and propose fixes
python3 scripts/webpack_config_validator.py suggest config.json
python3 scripts/webpack_config_validator.py suggest config.json --format json
Flags
| Flag |
Description |
--strict |
Treat warnings as errors — exit code 1 (CI-friendly) |
--format text |
Human-readable output (default) |
--format json |
Machine-readable JSON |
--format summary |
Compact summary with counts |
--mode production |
Override mode context for mode-specific rules (E3, O3) |
--mode development |
Override mode context for mode-specific rules |
Validation Rules (24)
Structure (5)
| Rule |
Severity |
Description |
| S1 |
error |
File not found or unreadable |
| S2 |
error |
Empty config file |
| S3 |
error |
Invalid JSON syntax |
| S4 |
error |
Missing required fields (entry, output) |
| S5 |
warning/info |
Unknown or deprecated top-level keys |
Entry/Output (4)
| Rule |
Severity |
Description |
| E1 |
error |
Empty entry point (empty string, object, or array) |
| E2 |
error |
Output section missing 'path' property |
| E3 |
warning |
Output filename without content hash in production mode |
| E4 |
warning |
publicPath not set |
Module/Rules (4)
| Rule |
Severity |
Description |
| M1 |
warning |
Module rule without 'test' pattern |
| M2 |
warning |
Duplicate loader for same test pattern |
| M3 |
warning |
Deprecated loaders (raw-loader, url-loader, file-loader, json-loader) |
| M4 |
info |
No babel-loader/ts-loader/esbuild-loader/swc-loader for JS/TS |
Plugins (4)
| Rule |
Severity |
Description |
| P1 |
error |
Deprecated plugins (UglifyJsPlugin, ExtractTextPlugin, CommonsChunkPlugin) |
| P2 |
warning |
Duplicate plugin instances |
| P3 |
info |
HtmlWebpackPlugin without explicit template |
| P4 |
warning |
MiniCssExtractPlugin without corresponding loader in rules |
Optimization (3)
| Rule |
Severity |
Description |
| O1 |
info |
Missing splitChunks configuration |
| O2 |
info |
Missing custom minimizer configuration |
| O3 |
warning/info |
devtool set to eval or source-map in production mode |
Best Practices (4)
| Rule |
Severity |
Description |
| B1 |
info |
Missing resolve.extensions |
| B2 |
warning |
Hardcoded absolute filesystem paths in config |
| B3 |
warning |
No mode set (development/production/none) |
| B4 |
info |
Missing devServer configuration |
Exit Codes
| Code |
Meaning |
| 0 |
No errors (warnings allowed unless --strict) |
| 1 |
Errors found (or warnings in --strict mode) |
| 2 |
File not found / parse error |
CI Integration
# GitHub Actions example
- name: Validate webpack config
run: |
node -e "console.log(JSON.stringify(require('./webpack.config.js')))" > /tmp/wp-config.json
python3 scripts/webpack_config_validator.py validate /tmp/wp-config.json --strict --mode production --format json
Example Output
webpack.config validate — config.json
======================================
[ERROR ] S4: Missing required top-level field(s): output
Every webpack config needs at least 'entry' and 'output'.
[WARNING] E4: output.publicPath not set
Set publicPath to ensure assets are loaded from the correct URL. Common values: '/', '/assets/', 'auto'.
[WARNING] M3: Deprecated loader 'file-loader' in rule 2
Replace with asset/resource (webpack 5 built-in).
[ERROR ] P1: Deprecated plugin 'UglifyJsPlugin' at index 0
Replace with TerserPlugin (terser-webpack-plugin).
[INFO ] O1: No optimization.splitChunks configuration
splitChunks enables automatic code splitting for shared dependencies. Add optimization: { splitChunks: { chunks: 'all' } } for better caching.
[WARNING] B3: No 'mode' set (development/production/none)
Set mode to enable webpack's built-in optimizations. Without mode, webpack defaults to 'production' with a warning.
Result: INVALID
Summary: 2 error(s), 3 warning(s), 1 info
