[Pacemaker] custom resource-agent

[David Lang]

On Tue, 1 Oct 2013, Dejan Muhamedagic wrote:

> Hi David,
>
> On Mon, Sep 30, 2013 at 12:41:23PM -0700, David Lang wrote:
>> On Mon, 30 Sep 2013, David Lang wrote:
>>
>>> On Mon, 30 Sep 2013, Michael Schwartzkopff wrote:
>>>
>>>> Am Montag, 30. September 2013, 21:12:56 schrieb Peter Romfeld:
>>>>> I am working in AWS i cant just use a VIP i need to use a floating
>>>>> secondary IP which i reassign through script, i want to let pacemaker
>>>>> handle the reassignment...
>>>>
>>>> Please explain the difference of a VIP and a "secondary IP" in
>>>> your opinion.
>>>
>>> with AWS you need to inform amazon of the change, not just change
>>> the IP on the local box, that requires much more work than a
>>> simple local VIP
>>
>> being more detailed, instead of just
>> ifconfig eth0:0 $vip
>> you have to do something like
>>
>> /opt/aws/bin/ec2-assign-private-ip-addresses -n $ENI_ID --secondary-private-ip-address $VIP --allow-reassignment --region $REGION
>
> We may consider adding such an option to IPaddr2. Has anybody
> ever tried that?
>
>> pingresult=`ping -c 1 -W 1 $VIP | grep time= | wc -l`
>> if [ "$pingresult" == "0" ]; then
>>   echo `date` "-- Restarting network"
>>   /sbin/service network restart > /dev/null 2>&1
>
> That may break the cluster communication, which may lead to split
> brain, etc. Is that really the only way?

It's not the only way, but you do have the problem that the call to aws 
management interface is asynchronous, you don't know when it's going to 
complete, and until it does, the IP doesn't actually work. During this migration 
time there's the possibility that trying to use the address will trigger 
problems (but enabling it early and listening shouldn't be a problem)

David Lang