用dockerfile構建node後端鏡像，出現如下問題。
Error: Package exports for '/app/node_modules/koa' do not define a valid '.' target
11:38:03 0|gov-test | at resolveExportsTarget (internal/modules/cjs/loader.js:460:13)
11:38:03 0|gov-test | at resolveExports (internal/modules/cjs/loader.js:393:16)
11:38:03 0|gov-test | at Function.Module._findPath (internal/modules/cjs/loader.js:492:20)
11:38:03 0|gov-test | at Function.Module._resolveFilename (internal/modules/cjs/loader.js:787:27)
11:38:03 0|gov-test | at Module.Hook._require.Module.require (/usr/local/lib/node_modules/pm2/node_modules/require-in-the-middle/index.j
11:38:03 0|gov-test | at require (internal/modules/cjs/helpers.js:74:18)
11:38:03 0|gov-test | at Object.<anonymous> (/app/server.js:39:13)
11:38:03 0|gov-test | at Module._compile (internal/modules/cjs/loader.js:971:30)
11:38:03 0|gov-test | at Object.Module._extensions..js (internal/modules/cjs/loader.js:1011:10)
11:38:03 0|gov-test | at Module.load (internal/modules/cjs/loader.js:822:32) {
11:38:03 0|gov-test | code: 'MODULE_NOT_FOUND'
11:38:03 0|gov-test | }
解決方法：
KOA版本問題，修改package.json中的KOA版本，看哪個版本可以。
dockerfile如下
FROM keymetrics/pm2:latest-alpine
ADD . /app/
WORKDIR /app
#RUN npm install -g cnpm –registry=https://registry.npm.taobao.org
COPY repositories /etc/apk/repositories
RUN npm config set registry https://registry.npm.taobao.org
RUN npm install
#RUN npm install @babel/plugin-transform-modules-commonjs
RUN npm uninstall koa
RUN npm install [email protected]
卸載原有的KOA，加載之前測試確定好的KOA，即可正常訪問。