vaz/vagrant-fixes-for-watch-polling.md

## vagrant-fixes-for-watch-polling.md

      
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              vagrant-fixes-for-watch-polling.md
            
          
    Vagrant fixes for file-watching servers

These snippets show how to enable polling for filesystem changes when using

nodemon for Node apps (ExpressJS, etc)
rails server
webpack-dev-server --watch
ember server

You can probably look at these examples and Google to find similar solutions for other dev servers.
Explanation

Development servers, transpilers and other build tools often provide a watch command, to watch for source file changes and recompile/reload automatically.
Programs running in a Vagrant VM usually can't detect file changes when a file is saved on the host OS (e.g. most editors). So you need to switch to polling (periodically checking for changes) instead.
(Compared to filesystem events, polling is slower to respond to changes and much more I/O-intensive, so it's not often enabled by default. Also, the issue actually belongs more specifically to VirtualBox and the way it does shared directories. Running Vagrant atop something like VMware may just work.)
Fixes

nodemon

nodemon is a tool for running NodeJS apps and automatically reloading whenever certain files change.
It seems nodemon can be used normally with varying success in Vagrant long bug thread here. If it doesn't reload properly:

Try using the -L flag (nodemon -L app.js)

If performance suffers or it takes too long to reload:

Try watching only specific directories (nodemon -L --watch src --watch lib)
and/or, try ignoring filename patterns you don't want to watch (nodemon -L --ignore 'dist/*.js'). nodemon should already ignore things like node_modules/* by default.

rails server

https://stackoverflow.com/questions/35959490/rails-server-doesnt-see-code-changes-and-reload-files
In config/environments/development.rb:
# uses filesystem events:
# config.file_watcher = ActiveSupport::EventedFileUpdateChecker

# uses polling:
config.file_watcher = ActiveSupport::FileUpdateChecker
FileUpdateChecker will use polling.
webpack-dev-server

Need to add these watch options to enable polling:
{
  aggregateTimeout: 300,
  poll: 1000,
  ignored: /node_modules/
}
Programmatically:
# server.js
var webpack = require('webpack');
var WebpackDevServer = require('webpack-dev-server');
var config = require('./webpack.config');

new WebpackDevServer(webpack(config), {
    publicPath: config.output.publicPath,
    watchOptions: {
      aggregateTimeout: 300,
      poll: 1000,
      ignored: /node_modules/
    }
  })
  .listen(3000, '0.0.0.0', function (err, result) {
    if (err) {
      console.log(err);
    }

    console.log('Running at http://0.0.0.0:3000');
  });
Or command-line:
node_modules/.bin/webpack-dev-server --host 0.0.0.0 --watch --watch-aggregate-timeout 300 --watch-poll 1000

Note: Not sure if --watch-ignore is a thing or if it works, or how to ignore a filename pattern on the command-line. But ignoring the regex pattern /node_modules/ improves performance a lot (only works for Webpack 2.x).
ember server

In .ember-cli, add these properties:
"liveReload": true,
"watcher": "polling"
or invoke the serve command using the polling watcher:
ember serve --watcher polling