Overwriting config parameters through CLI

[webpack-bot]

Do you want to request a feature or report a bug?

feature

What is the current behavior?

According to my understanding and tests, I can use webpack either in combination with a config file which includes the entry and output paths, or I can pass the entry and output path as CLI arguments. But both alternatives are mutually exclusive, i.e. I cannot overwrite the entry and output paths specified in a config file through CLI parameters, while still using the other specifications in the config file.

If the current behavior is a bug, please provide the steps to reproduce.

What is the expected behavior?

I want to use a webpack.config.js AND overwrite the entry and output paths of that config file using CLI parameters.

If this is a feature request, what is motivation or use case for changing the behavior?

I need to change entry and output paths dynamically and depending on some context while keeping the other entries of an entry file.

Please mention other relevant information such as the browser version, Node.js version, webpack version and Operating System.

---

This issue was moved from webpack/webpack#4895 by @bebraw. Orginal issue was by @fera0013.

[kristoforsalmin]

Hi,

That's a great idea! I don't know if that would be helpful, but PostCSS CLI handles this in a nice manner. They have a ctx object passed into your config that contains all processed CLI options.

https://github.com/postcss/postcss-cli/blob/master/index.js#L126 and then in your config you can:

module.exports = ({ options }) => ({
  map: options.map,
  ...
});

It actually would be great if that would be possible with the webpack CLI as well. I often need dynamically set context, path or publicPath. For example if I were to run webpack src/scripts/main.js -o dist/scripts/[name].bundle.js, then I'd be awesome to have something like this:

const path = require('path');

module.exports = ({ options }) => ({
  output: {
    publicPath: `/${options.outputPath.split(path.sep).pop()}/`
  }
  ...
});

Thanks! 😄

[bitpshr]

The example usage printed by the CLI is a bit misleading:

Usage without config file: webpack <entry> [<entry>] --output [-o] <output>
Usage with config file: webpack

The current implementation always tries to find a configuration file, using either a list of default names (e.g. webpack.config.js) or using the path specified for the --config CLI option. Regardless of whether a configuration file is actually specified or found, new entry points can always be dynamically added using the webpack <entry> or webpack --entry syntax, and the output can always be dynamically modified using the --output CLI option.

The issue I see with the current implementation is that new entry points are always appended when using webpack <entry> or webpack --entry syntax, even when a configuration file is found. This sort of makes the OP's original end goal more difficult (if not impossible), to override entry and output specified in a configuration file via CLI arguments. It's currently possible to override output but only possible to append to entry.

I propose that any entry points specified via CLI options override any entry configuration specified in a configuration file rather than appending to it. Thoughts? @ev1stensberg @ematipico @dhruvdutt

[evenstensberg]

Send a PR

[bitpshr]

@ev1stensberg see #358.

[evenstensberg]

Closed via #358