Recommend users to set a higher inotify watches limit for Kibana

[marius-dr]

Kibana version: master

Server OS version: Ubuntu LTS 18.04

Original install method (e.g. download page, yum, from source, etc.): source

@hendrikmuhs hit this today:

Error: ENOSPC: System limit for number of file watchers reached, watch '/home/hendrik/work/git-elastic/kibana/src/ui/public/vis/vis_types/_vislib_vis_legend.scss'
    at FSWatcher.start (internal/fs/watchers.js:165:26)
    at Object.watch (fs.js:1254:11)
    at createFsWatchInstance (/home/hendrik/work/git-elastic/kibana/node_modules/chokidar/lib/nodefs-handler.js:37:15)
    at setFsWatchListener (/home/hendrik/work/git-elastic/kibana/node_modules/chokidar/lib/nodefs-handler.js:80:15)
    at FSWatcher.NodeFsHandler._watchWithNodeFs (/home/hendrik/work/git-elastic/kibana/node_modules/chokidar/lib/nodefs-handler.js:228:14)
    at FSWatcher.NodeFsHandler._handleFile (/home/hendrik/work/git-elastic/kibana/node_modules/chokidar/lib/nodefs-handler.js:255:21)
    at FSWatcher.<anonymous> (/home/hendrik/work/git-elastic/kibana/node_modules/chokidar/lib/nodefs-handler.js:473:21)
    at FSReqWrap.oncomplete (fs.js:155:5)

Looks like with the recent additions to Kibana we might hit the default limit on certain OSs. I think we should do the same thing that ES uses for file descriptors:

• add a bootstrap check (could be a warning for now)
• add a note in the docs on the error message and what to do to fix this:
  changing fs.inotify.max_user_watches=8192 in /etc/sysctl.conf to a higher number.
  We can also investigate the increase in file watches and see if we can limit that somehow.

[elasticmachine]

Pinging @elastic/kibana-platform

[elasticmachine]

Pinging @elastic/kibana-app

[elasticmachine]

Pinging @elastic/kibana-operations

[spalger]

Note that file watchers are only setup in development so this shouldn't require adding bootstrap checks to Kibana necessarily, but adding a test for that error along with instructions for how to increase the max watches on linux would certainly be helpful.