Packaging bug when using nodejs based custom runtime

This is a Bug

Description

I am trying to have a custom runtime for one of my lambda function. However when I specify runtime: provided webpack is not packaging my function as expected. Instead is packaging the whole project including all the other functions. If my runtime is not provided (just standard nodejs) then the packaging is correct. Without webpack plugin it works fine as well.

I have a repro case here: https://github.com/MatteoGioioso/serverless-webpack-bug

Additional Data

• Serverless-Webpack Version you’re using: 5.3.4
• Webpack version you’re using: 4.29.6
• Serverless Framework Version you’re using:

Framework Core: 1.77.1
Plugin: 3.6.18
SDK: 2.3.1
Components: 2.33.2

Webpack configuration

const path = require('path');
const nodeExternals = require('webpack-node-externals');
const slsw = require('serverless-webpack');

module.exports = {
  entry: slsw.lib.entries,
  target: 'node',
  devtool: 'source-map',

  externals: [nodeExternals()],
  module: {
    rules: [
      {
        test: /\.js$/,
        use: {
          loader: 'babel-loader',
          options: {
            presets: ['@babel/preset-env'],
          },
        },
        include: __dirname,
        exclude: /node_modules/,
      },
    ],
  },
  output: {
    libraryTarget: 'commonjs2',
    path: path.join(__dirname, '.webpack'),
    filename: '[name].js',
    sourceMapFilename: '[file].map',
  },
};

Serverless.yaml simplified

service: sls-webpack-bug

provider:
  name: aws
  runtime: nodejs12.x

custom:
  webpack:
    webpackConfig: ./webpack.config.js

package:
  individually: true

plugins:
  - serverless-webpack

functions:
  exampleFunction:
    memorySize: 1024
    timeout: 30
    handler: services/myService/handler.default
    runtime: provided

  exampleFunction2:
    memorySize: 1024
    timeout: 30
    handler: services/anotherService/myHandler.default

If I have time I will make a repro case, but I think that should be it for the time being.

PS: The custom runtime is nodejs in this case

Thanks

[MatteoGioioso]

@j0k3r ok, I can update the docs as well in the same PR if you guys need

[MatteoGioioso]

@j0k3r ok, I have made a PR for this!