netdata/health/health.d/file_descriptors.conf

 # you can disable an alarm notification by setting the 'to' line to: silent

  template: system_file_descriptors_utilization
        on: system.file_nr_utilization
     class: Utilization
      type: System
 component: Processes
     hosts: *
    lookup: max -1m unaligned
     units: %
     every: 1m
      crit: $this > 90
     delay: down 15m multiplier 1.5 max 1h
   summary: System open file descriptors utilization
      info: System-wide utilization of open files
        to: sysadmin

 template: apps_group_file_descriptors_utilization
       on: app.fds_open_limit
    class: Utilization
     type: System
component: Process
       os: linux
   module: *
    hosts: *
   lookup: max -10s unaligned foreach *
    units: %
    every: 10s
     warn: $this > (($status >= $WARNING)  ? (85) : (95))
    delay: down 15m multiplier 1.5 max 1h
  summary: App group ${label:app_group} file descriptors utilization
     info: Open files percentage against the processes limits, among all PIDs in application group
       to: sysadmin