Security Group: limit returns in get_bridge_physdev to 1

[RPDiep]

Description

We've encountered a corner case where bridge -o link show returned two lines per bridge instead of one. get_bridge_physdev in security_group.py returned bond0.701\nbond0.701.
Although this may very well be something on the hypervisor, we should limit the lines returned.
I therefore added a mere | head -1 to the function.

See output:
Old:

root@n02:~# bridge -o link show | awk '/master cloudbr0 / && !/^[0-9]+: vnet/ {print $2}'
bond0.701
bond0.701

New:

root@n02:~# bridge -o link show | awk '/master cloudbr0 / && !/^[0-9]+: vnet/ {print $2}' | head -1
bond0.701

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)

Screenshots (if appropriate):

How Has This Been Tested?

Tested function from idle:

root@n02:/usr/share/cloudstack-common/scripts/vm/network# python
Python 2.7.12 (default, Oct  8 2019, 14:14:10) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from security_group import get_bridge_physdev
>>> get_bridge_physdev('cloudbr0')
'bond0.701'

Please let me know if you want me to rebase against 4.13 .

[GabrielBrascher]

Code LGTM, thanks @RPDiep!

[RPDiep]

Rebased against 4.13 as requested by @GabrielBrascher

[ustcweizhou]

@RPDiep @GabrielBrascher
I did not see this issue on all our platforms. we also use bonding on some platforms.
it seems to be caused by another issue.
could you please paste result of command "bridge -o link show | awk '/master cloudbr0 /'

[RPDiep]

@ustcweizhou

I'm sure this is something now on the hypervisor, but it appears that corner cases exist in which a second line appears. As we only need one result, I added the | head -1 in this commit.

Here's the output you requested (I added the vnet filter)

root@n02:~# bridge -o link show | awk '/master cloudbr0 / && !/^[0-9]+: vnet/'
7: bond0.701 state UP @bond0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master cloudbr0 state forwarding priority 32 cost 2 
7: bond0.701 state UP @bond0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master cloudbr0 

[yadvr]

@blueorangutan package

[blueorangutan]

@rhtyd a Jenkins job has been kicked to build packages. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result: ✔centos6 ✔centos7 ✔debian. JID-325

[ustcweizhou]

state forwarding priority 32 cost 2

@RPDiep thanks . this change looks good to me.

[yadvr]

Thanks for confirming the change and tests. I'll merge this.