Docker+node+express且つnodeユーザー+80番ポートでexpress起動できなかった件

自分用の覚書

環境

	ver
Docker	1.11.2
node	7.9-alpine
express	4.15.2

症状

$ docker run --rm -it --user node node:7.9-alpine ash

$ cd /home/node
$ yarn add express
$ node -i
> const express = require('express');
> const app = express();
> app.listen(80, () => { console.log('listen on port 80'); });
Server {
~ 割愛 ~
  maxHeadersCount: null }
> Error: listen EACCES 0.0.0.0:80
    at Object.exports._errnoException (util.js:1050:11)
    at exports._exceptionWithHostPort (util.js:1073:20)
    at Server.setupListenHandle [as _listen2] (net.js:1247:19)
    at listenInCluster (net.js:1304:12)
    at Server.listen (net.js:1402:7)
    at Function.listen (/opt/node_modules/express/lib/application.js:618:24)
    at repl:1:5
    at ContextifyScript.Script.runInThisContext (vm.js:23:33)
    at REPLServer.defaultEval (repl.js:339:29)
    at bound (domain.js:280:14)

参考

• http://stackoverflow.com/questions/35068712/error-listen-eacces-0-0-0-080-osx-node-js

ポート番号を変えると良い的な

対処

$ docker run --rm -it --user node node:7.9-alpine ash

$ cd /home/node
$ yarn add express
$ node -i
> const express = require('express');
> const app = express();
> app.listen(18081, () => { console.log('listen on port 18081'); });
Server {
~ 割愛 ~
  _connectionKey: '6::::18081' }
> listen on port 18081

最後に

rootユーザーなら起動できる