1. Add the following line to /etc/rc.local:
    varnishncsa -a -w /var/log/varnish/access.log -D -P /var/run/varnishncsa.pid
  2. Configure logrotate by adding the following line to
    /etc/logrotate.d/varnish
    (create it if it doesn't exist):
    /var/log/varnish/*log {
        create 640 http log
        compress
        postrotate
            /bin/kill -USR1 `cat /var/run/varnishncsa.pid 2>/dev/null` 2> /dev/null || true
        endscript
    }
  3. Add a local file source to your collector pointing to the path defined above