Kibana refuses to start if metrics collector can't access sysfs

[weltenwort]

Kibana version: master as of 6d819b7

Elasticsearch version: 8.0.0-SNAPSHOT

Server OS version: Linux 5.8.10-arch1-1 #1 SMP PREEMPT Thu, 17 Sep 2020 18:01:06 +0000 x86_64 GNU/Linux (Arch Linux)

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

Describe the bug:

Kibana refuses to start if it's not allowed to access /sys/fs/cgroup/cpuacct/cpuacct.usage. It terminates after logging the following:

  log   [00:00:00.000] [fatal][root] { [Error: EACCES: permission denied, open '/sys/fs/cgroup/cpuacct/cpuacct.usage']
  errno: -13,
  code: 'EACCES',
  syscall: 'open',
  path: '/sys/fs/cgroup/cpuacct/cpuacct.usage' }

Steps to reproduce:

1. Set up a namespace in which the user doesn't have read permissions on /sys/fs.
2. Start Kibana in development mode via yarn start within that namespace as the restricted user.
3. Observe that it terminates after printing the log message shown above.

Expected behavior:

It starts, possibly while logging a warning (as it did a while ago).

Any additional context:

This is possibly related to #76730.

[elasticmachine]

Pinging @elastic/kibana-platform (Team:Platform)

[weltenwort]

Thanks for the quick fix ❤️ I verified that it now logs the error but continues to start:

  log   [00:00:00.000] [error][cgroup][metrics] cgroup metrics could not be read due to error: [Error: EACCES: permission denied, open '/sys/fs/cgroup/cpuacct/cpuacct.usage']