Logrotate problems (I think)

[Cylindric (Mark Hanford)]

I have a fairly high-volume log file source (Varnish) that I'm trying to push into ES.

What I'm seeing, is FileBeat seems to start logging every hour, roughly on the hour, but only for a few minutes (seems to vary between 5 and 20 minutes). Then it goes mostly quiet until the next hour.

That felt to me like a log-rotation problem, but I thought Filebeat would keep an eye on a file that was rotated out the way?

I am rotating hourly:

/var/log/varnish/varnishncsa.log {
    rotate 4
    hourly
    missingok
    notifempty
    sharedscripts
    nocompress
    postrotate
        /bin/kill -HUP `cat /var/run/varnishlog.pid 2>/dev/null` 2> /dev/null || true
        /bin/kill -HUP `cat /var/run/varnishncsa.pid 2>/dev/null` 2> /dev/null || true
    endscript
}

And my Prospector is setup like this:

filebeat.prospectors:

-
  type: log
  document_type: varnish
  close_inactive: 1m
  ignore_older: 15m
  paths:
    - /var/log/varnish/varnishncsa.log
  json.keys_under_root: true
  json.add_error_key: true
  json.overwrite_keys: true

output.elasticsearch:
  index: "varnish-%{+yyyy.MM.dd}"
  pipeline: varnish
  bulk_max_size: 2000
  template.enabled: false
  hosts: ["https://mycluster.eu-west-1.aws.found.io:9243"]
  username: ""
  password: ""
  compression_level: 9

I used close_inactive:1m because as per the docs, that is much longer than the gap between events, and ignore_older:15m because I don't want to rescan old files after a FileBeat restart.

[ruflin]

It seems some of the logs are still shipped during the "silend" period. Did you have a look at the logs on what is happening there?

In general I would recommend to use /var/log/varnish/varnishncsa.log* or something similar which matches your rotation. So also on restart of filebeat and a file was rotated, it will still pick it up an finish reading.