Vue CLI3升级至Vue CLI5构建报错：多chunk输出同名资源求助

问题场景 #

将项目从Vue CLI3升级至Vue CLI5后，为避免小于8KiB的资源被转换为Data URL，在vue.config.js的chainWebpack中添加了以下配置：

const imagesRule = config.module.rule('images');
imagesRule.set('parser', {
  dataUrlCondition: {
   maxSize: 0.1 * 1024
}
})

构建时出现报错：

Conflict: Multiple chunks emit assets to the same filename static/img/xxx.png (chunks 685 and 4880)

完整vue.config.js内容如下：

'use strict'
const path = require('path')
const defaultSettings = require('./src/settings.js')
const shell = require('shelljs')
const fs = require('fs')
const address = require('address')

function resolve(dir) {
  return path.join(__dirname, dir)
}

const name = defaultSettings.title || 'vue Admin Template' // page title

const port = process.env.port || process.env.npm_config_port || 8888 // dev port

if (/build/g.test(process.env.npm_config_argv) && fs.existsSync(path.resolve(__dirname, './dist'))) shell.rm('-rf', 'dist')
module.exports = {
  publicPath: 'xxx',
  outputDir: 'dist',
  assetsDir: 'static',
  lintOnSave: false,
  productionSourceMap:false,
  filenameHashing: false,
  devServer: {
    port: port,
    hot: true,
    open: false,
    allowedHosts: 'all',
    client: {
      overlay: {
        warnings: false,
        errors: false
      },
    },
    server: 'https'
  },
  configureWebpack: {
    // provide the app's title in webpack's name field, so that
    // it can be accessed in index.html to inject the correct title.
    name: name,
    resolve: {
      alias: {
        '@': resolve('src')
      }
    },
    cache: {
      type: 'filesystem',
      buildDependencies: {
        // 当配置修改时，缓存失效
        config: [__filename],
      },
    },
  },
  chainWebpack(config) {
    config.plugins.delete('preload') // TODO: need test
    config.plugins.delete('prefetch') // TODO: need test
    const imagesRule = config.module.rule('images');
    imagesRule.set('parser', {
      dataUrlCondition: {
        maxSize: 0.1 * 1024
      }
    })
    // set svg-sprite-loader
    config.module
      .rule('svg')
      .exclude.add(resolve('src/icons'))
      .end()
    config.module
      .rule('icons')
      .test(/\.svg$/)
      .include.add(resolve('src/icons'))
      .end()
      .use('svg-sprite-loader')
      .loader('svg-sprite-loader')
      .options({
        symbolId: 'icon-[name]'
      })
      .end()

    // set preserveWhitespace
    config.module
      .rule('vue')
      .use('vue-loader')
      .loader('vue-loader')
      .tap(options => {
        options.compilerOptions.preserveWhitespace = true
        return options
      })
      .end()

    config
    // https://webpack.js.org/configuration/devtool/#development
      .when(process.env.NODE_ENV === 'development',
        config => config.devtool('cheap-module-source-map')
      )

    config
      .when(process.env.NODE_ENV !== 'development',
        config => {
          config
            .plugin('ScriptExtHtmlWebpackPlugin')
            .after('html')
            .use('script-ext-html-webpack-plugin', [{
            // `runtime` must same as runtimeChunk name. default is `runtime`
              inline: /runtime\..*\.js$/
            }])
            .end()
          config
            .optimization.splitChunks({
              chunks: 'all',
              cacheGroups: {
                libs: {
                  name: 'chunk-libs',
                  test: /[\\/]node_modules[\\/]/,
                  priority: 10,
                  chunks: 'initial' // only package third parties that are initially dependent
                },
                elementUI: {
                  name: 'chunk-elementUI', // split elementUI into a single package
                  priority: 20, // the weight needs to be larger than libs and app or it will be packaged into libs or app
                  test: /[\\/]node_modules[\\/]_?element-ui(.*)/ // in order to adapt to cnpm
                },
                commons: {
                  name: 'chunk-commons',
                  test: resolve('src/components'), // can customize your rules
                  minChunks: 3, //  minimum common number
                  priority: 5,
                  reuseExistingChunk: true
                }
              }
            })
          config.optimization.runtimeChunk('single')
        }
      )
  }
}

原因分析 #

报错核心原因是关闭了文件名哈希（filenameHashing: false）+ 强制所有图片输出为文件而非Data URL：

• Vue CLI3默认会将小图转为Data URL嵌入代码，不会生成独立文件，因此不存在多Chunk输出同文件名的问题；
• 修改dataUrlCondition.maxSize为0.1KB后，几乎所有图片都会被webpack输出为独立文件；
• 开启代码分割（splitChunks）后，若多个Chunk引用同一张图片，关闭哈希的情况下，webpack会尝试将图片输出为相同的文件名，导致冲突。

解决方案 #

方案1：开启文件名哈希（推荐，最简单） #

将vue.config.js中的filenameHashing: false修改为true，webpack会自动给图片文件名添加哈希后缀，避免重名冲突：

module.exports = {
  // ...其他配置
  filenameHashing: true,
  // ...其他配置
}

方案2：保留filenameHashing: false，自定义图片输出文件名模板 #

如果必须关闭全局哈希，可以单独给图片配置带内容哈希的文件名模板，修改chainWebpack中的图片规则：

chainWebpack(config) {
  // ...其他配置
  const imagesRule = config.module.rule('images');
  imagesRule.set('parser', {
    dataUrlCondition: {
      maxSize: 0.1 * 1024
    }
  }).set('generator', {
    // 给图片文件名添加8位内容哈希，既避免冲突又不影响文件名可读性
    filename: 'static/img/[name].[contenthash:8][ext]'
  })
  // ...其他配置
}

方案3：优化代码分割配置，减少重复引用 #

检查splitChunks的commons缓存组配置，调整minChunks或test范围，避免将引用同一张图片的组件拆分到多个Chunk中，但此方案对项目结构依赖较大，优先级低于前两种。

内容的提问来源于stack exchange，提问作者Dreams