webpack.config.js

const execSync = require('child_process').execSync;
const fs = require('fs');
const webpack = require('webpack');
const marked = require('marked');

module.exports = (env, argv) => {
  return {
    plugins: [
      // @NOTE: Generate CHANGELOG.md (from git log + current CHANGELOG.md), put it in bundle
      env.NODE_ENV === 'production' && {
        apply: (compiler) => {
          const { RawSource } = webpack.sources;
          compiler.hooks.thisCompilation.tap('GitLogPlugin', (compilation) => {
            compilation.hooks.processAssets.tap(
              {
                name: 'GitLogPlugin',
                stage: compiler.webpack.Compilation.PROCESS_ASSETS_STAGE_ADDITIONAL,
              },
              () => {
                let changelog = '';

                try {
                  changelog = fs.readFileSync('./CHANGELOG.md').toString();
                } catch (err) {
                  console.error(`Couldn't read file ${'./CHANGELOG.md'}`);
                  return;
                }

                try {
                  // Last git tag
                  const gitTag = execSync('git tag --sort=-taggerdate').toString().split('\n')[0];

                  // Last git log
                  const gitLog = execSync(`git log --pretty="* %s" --no-merges HEAD...${gitTag}`);

                  // Final changelog
                  changelog = `# New since last (${gitTag}) release\n\n${gitLog}\n${changelog}`;
                } catch (err) {
                  console.error(err);
                  console.error('Couldn\'t generate git log');
                } finally {
                  // @NOTE: Put final CHANGELOG.md in bundle
                  compilation.emitAsset('CHANGELOG.md', new RawSource(changelog));

                  // @NOTE: Generate .html for comfortable reading
                  compilation.emitAsset('CHANGELOG.html', new RawSource(marked.parse(changelog)));
                }
              },
            );
          });
        },
      },
    ]
  }
}