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Bug 1148012

Summary:	RFE: Allow qemu-bridge-helper to be used to implement guestfs_set_network
Product:	[Community] Virtualization Tools	Reporter:	Richard W.M. Jones <rjones>
Component:	libguestfs	Assignee:	Richard W.M. Jones <rjones>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	unspecified	CC:	laine, mbooth, ptoscano, rbalakri
Target Milestone:	---
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2014-10-02 22:11:49 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1146320, 1147057
Bug Blocks:

Description Richard W.M. Jones 2014-09-30 14:10:24 UTC

Description of problem:

See: https://lists.fedoraproject.org/pipermail/virt/2014-September/004179.html
and followups.

qemu has a setuid program called 'qemu-bridge-helper' which
apparently we can use to connect to virbr0 and get real
networking instead of using SLIRP.

This would only apply to the libvirt backend.

Comment 1 Laine Stump 2014-09-30 14:54:50 UTC

On a system that is already doing this for boxes, all that would be required would be to use the following interface definition:

  <interface type='bridge'>
    <source bridge='virbr0'/>
    ...
  </interface>

the bridge helper looks in /etc/qemu/bridge.conf to see which bridges it can use, and which users can request taps connected to those bridges. On Fedora at least, by default this file contains:

   allow virbr0

which means that any uid can request a new tap device connected to virbr0. Apparently, this particular bridge.conf file is installed as part of the qemu-common package.

Comment 2 Richard W.M. Jones 2014-09-30 15:08:55 UTC

That change would be quite simple to make in libguestfs .. but
using virbr0 would require dhcp I think?  Unfortunately the
guestfs appliance would really like a fixed IP address assigned
in advance.  I guess we might be able to run dhclient, assuming
there is not too much speed penalty.

Comment 3 Richard W.M. Jones 2014-09-30 15:44:49 UTC

These two patches implement the general idea:

https://www.redhat.com/archives/libguestfs/2014-September/msg00293.html
https://www.redhat.com/archives/libguestfs/2014-September/msg00294.html

Comment 4 Richard W.M. Jones 2014-10-02 11:41:01 UTC

v2 patch:
https://www.redhat.com/archives/libguestfs/2014-October/msg00007.html

Comment 5 Richard W.M. Jones 2014-10-02 15:37:16 UTC

Patches upstream, but blocked by bug 1146320 on Rawhide.