This ticket may be just the ticket :)

https://issues.apache.org/jira/browse/CASSANDRA-2452

Cheers

-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

On 27 May 2011, at 01:16, Sasha Dolgy wrote:

> As an aside, you can also use that command to pull meta-data about
> instances in AWS.  I have implemented this to maintain a list of seed
> nodes.  This way, when a new instance is brought online, the default
> cassandra.yaml is `enhanced` to contain a dynamic list of valid seeds,
> proper hostname and a few other bits of useful information.
> 
> Finally, if you aren't using a single security group for all of your
> cassandra instances, maybe this may be of help to you.  When we add
> new nodes to our ring, we add them to a single cassandra security
> group.  No messing about with security groups per instance...
> 
> -sd
> 
> On Thu, May 26, 2011 at 2:36 PM, Marcus Bointon
> <mar...@synchromedia.co.uk> wrote:
>> Thanks for all your helpful suggestions - I've now got it working. It was 
>> down to a combination of things.
>> 
>> 1. A missing rule in a security group
>> 2. A missing DNS name for the new node, so its default name was defaulting 
>> to localhost
>> 3. Google DNS caching the failed DNS lookup for the full duration of the 
>> SOA's TTL
>> 
>> In order to avoid the whole problem with assigning IPs using the 
>> internal/external trick and using up elastic IPs, I found this service which 
>> I'd not seen before: 
>> http://www.ducea.com/2009/06/01/howto-update-dns-hostnames-automatically-for-your-amazon-ec2-instances/
>> 
>> This means you can reliably set (and reset as necessary) a listen address 
>> with this command:
>> 
>> sed -i "s/^listen_address:.*/listen_address: `curl 
>> http://169.254.169.254/latest/meta-data/local-ipv4`/"; 
>> /etc/cassandra/cassandra.yaml
>> 
>> It's not quite as good as having a true dynamic hostname, but at least you 
>> can drop it in a startup script and forget it.
>> 
>> Marcus

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