Bug 1351666

+++ This bug was initially created as a clone of Bug #1351209 +++

Description of problem:
KVM guest is set up to redirect console output into a file, which is monitored by part of Beaker's /distribution/virt/install test, that uploads new chunks to Beaker server:

   <serial type='file'>
      <source path='/mnt/tests/distribution/virt/install/guests/ppc64le_kvm8_2cpu/logs/ppc64le_kvm8_2cpu_console.log'/>
      <target port='0'/>
      <alias name='serial0'/>
      <address type='spapr-vio' reg='0x30000000'/>
    </serial>
    <console type='file'>
      <source path='/mnt/tests/distribution/virt/install/guests/ppc64le_kvm8_2cpu/logs/ppc64le_kvm8_2cpu_console.log'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
      <address type='spapr-vio' reg='0x30000000'/>
    </console>

virtlogd starts rotating logs and any application monitoring original file is left with fd that is no longer getting updates:

-rw-------. 1 root root  24159 Jun 29 08:37 ppc64le_kvm8_2cpu_console.log
-rw-------. 1 root root 131072 Jun 29 07:19 ppc64le_kvm8_2cpu_console.log.0
-rwxrwxrwx. 1 qemu qemu 131072 Jun 29 07:01 ppc64le_kvm8_2cpu_console.log.1

# fuser `pwd`/ppc64le_kvm8_2cpu_console.log
/mnt/tests/distribution/virt/install/guests/ppc64le_kvm8_2cpu/logs/ppc64le_kvm8_2cpu_console.log:  6416

# fuser `pwd`/ppc64le_kvm8_2cpu_console.log.1
/mnt/tests/distribution/virt/install/guests/ppc64le_kvm8_2cpu/logs/ppc64le_kvm8_2cpu_console.log.1:  6217

# ps afx | grep -e 6416 -e 6217
113741 pts/2    S+     0:00          \_ grep --color=auto -e 6416 -e 6217
  6217 ?        Ss     0:05 /usr/local/bin/logguestconsoles --config /usr/local/etc/logguestconsoles.conf
  6416 ?        Ssl    0:02 /usr/sbin/virtlogd


Version-Release number of selected component (if applicable):
libvirt-1.3.5-1.el7

How reproducible:
100%

Steps to Reproduce:
1. redirect serial console to file
2. open file
3. let guest write more than 128kb to serial console
4. file is rotated, and fd open at 2) is not getting updates anymore

Actual results:
virtlogd breaks apps that monitor guest console logs

Expected results:
1. larger default value for DEFAULT_FILE_SIZE, say 2M
2. option to override DEFAULT_FILE_SIZE

Additional info:

--- Additional comment from RHEL Product and Program Management on 2016-06-29 10:25:47 EDT ---

Since this bug report was entered in bugzilla, the release flag has been
set to ? to ensure that it is properly evaluated for this release.

--- Additional comment from Red Hat Bugzilla Rules Engine on 2016-06-29 10:25:54 EDT ---

This bug report has Keywords: Regression or TestBlocker.

Since no regressions or test blockers are allowed between releases, it is also being [proposed|marked] as a blocker for this release.

Please resolve ASAP.

--- Additional comment from Daniel Berrange on 2016-06-30 05:29:23 EDT ---

You have the option of disabling virtlogd in /etc/libvirt/qemu.conf via the stdio_handler property.

Allowing the max size before rollover to be configurable is a valid future RFE too.

--- Additional comment from Jan Stancek on 2016-06-30 07:19:10 EDT ---

(In reply to Daniel Berrange from comment #3)
> You have the option of disabling virtlogd in /etc/libvirt/qemu.conf via the
> stdio_handler property.

Thanks for the tip, I'll look into creating a patch for beaker, that configures the old unlimited behaviour.