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From: "Musayev, Ilya" <imusayev@webmd.net>
To: "cloudstack-users@incubator.apache.org"
	<cloudstack-users@incubator.apache.org>
Subject: RE: alter resolv.conf nameservers on linux
Thread-Topic: alter resolv.conf nameservers on linux
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Date: Thu, 8 Nov 2012 17:34:11 +0000
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References: <CCC04582.361C7%chiradeep.vittal@citrix.com>
 <F04B89F1-0403-4A66-B89F-76E1C7BC6CF2@me.com>
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I guess we can pre-stage our resolv.conf in template and  edit  /etc/dhclie=
nt-enter-hooks

Append code:

make_resolv_conf(){
	:
}

Save and close the file.=20
Works on RHEL, Debian-like will have something similar..

Push the template into CS - that should avoid dhcp updating resolv.conf

We can also do "chattr +i /etc/resolv.conf" to make it immutable - that's m=
ore of a brick and mortar approach.

It's a work around - not a solution.

Regards
ilya

-----Original Message-----
From: Caleb Call [mailto:calebcall@me.com]=20
Sent: Wednesday, November 07, 2012 11:40 PM
To: cloudstack-users@incubator.apache.org
Subject: Re: alter resolv.conf nameservers on linux

Sorry, yes, setting the global parameter does not work.  The contents of my=
 /etc/resolv.conf is:

# cat /etc/resolv.conf
; generated by /sbin/dhclient-script
search cs1cloud.internal
nameserver <ip of my vrouter>

I can edit it to what I want it to be, restart the instance and it gets cha=
nged back to this.  This happens across all my zones in all my different Cl=
oudstack environments.  DNS is configured correctly for them.

The reason for my desire to not use my virtual router is two fold.  First, =
I have found the name resolution (forwarding if you will) through the VR to=
 be spotty at best.  To correct it, I usually have to bounce my VR, it's li=
ke it just stops passing traffic.  This is happening in both of my Cloudsta=
ck environments.  Second, running a single nameserver is by no means accept=
able in any environment.  I wouldn't do it in my dev, test, or stage enviro=
nments let alone my production environment.  We also specify additional par=
ameters in /etc/resolv.conf like timeout and we have to be able to specify =
additional search domains.


On Nov 7, 2012, at 6:07 PM, Chiradeep Vittal <Chiradeep.Vittal@citrix.com> =
wrote:

> Not sure what you mean by #2. Do you mean that you set the global=20
> configuration flag use.external.dns ?
> If so, what is the content of /etc/resolv.conf ?
>=20
> Why is the DNS forwarder not working for you? Is your zone dns=20
> configured correctly in CloudStack?
>=20
> On 11/7/12 4:06 PM, "Caleb Call" <calebcall@me.com> wrote:
>=20
>> #2 doesn't work.  It still stomps /etc/resolv.conf with what's=20
>> provided by the routervm.
>>=20
>> On Nov 7, 2012, at 4:48 PM, Caleb Call <calebcall@me.com> wrote:
>>=20
>>> Thanks, #2 looks perfect.  I'll give that a shot.
>>>=20
>>> On Nov 7, 2012, at 4:29 PM, Chiradeep Vittal=20
>>> <Chiradeep.Vittal@citrix.com> wrote:
>>>=20
>>>> That should not be necessary. The DNS server in the router is a
>>>> forwarder:
>>>> 1. If the target of the DNS resolve is for a VM it has served DHCP=20
>>>> to, it responds with the entry 2. If not, it forwards it to the=20
>>>> 'zone' dns server.
>>>>=20
>>>> Or, you can set use.external.dns to 'true', restart the management=20
>>>> server and restart (from the api/ui) the virtual router.
>>>> But if you do, you won't get #1.
>>>>=20
>>>> On 11/7/12 3:12 PM, "Alex Huang" <Alex.Huang@citrix.com> wrote:
>>>>=20
>>>>> In 4.0, what I would do is this.
>>>>>=20
>>>>> - Write a plugin.
>>>>> - Listen to vm start events.
>>>>> - On router vm start, ssh into the router vm and change the=20
>>>>> resolv.conf
>>>>>=20
>>>>> In the next release, Murali have added proper external event=20
>>>>> system then you don't even need to do this via a plugin.
>>>>>=20
>>>>> --Alex
>>>>>=20
>>>>> -----Original Message-----
>>>>> From: Caleb Call [mailto:calebcall@me.com]
>>>>> Sent: Wednesday, November 07, 2012 3:06 PM
>>>>> To: cloudstack-users@incubator.apache.org
>>>>> Subject: Re: alter resolv.conf nameservers on linux
>>>>>=20
>>>>> Good question, I've been meaning to ask this same thing and keep=20
>>>>> forgetting to.  I think I've read that you have to edit the config=20
>>>>> on the router vm, but that doesn't persist a reboot of the router=20
>>>>> vm.  Is there a better way to do this?
>>>>>=20
>>>>>=20
>>>>> On Nov 7, 2012, at 3:18 PM, "Musayev, Ilya" <imusayev@webmd.net>
>>>>> wrote:
>>>>>=20
>>>>>> How would I pass on my nameservers in resolv.conf of an instance,=20
>>>>>> instead of router vms IP?
>>>>>>=20
>>>>>> As of now, my nameserver is set to ip address of router vm.
>>>>>>=20
>>>>>>=20
>>>>>> Thanks
>>>>>> ilya
>>>>>=20
>>>>=20
>>>=20
>>=20
>=20