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From Renato Perini <renato.per...@gmail.com>
Subject Re: Cassandra Configuration VS Static IPs.
Date Sun, 04 Oct 2015 23:10:26 GMT
Yes, the client uses the same datacenter (us-west-2).
Maybe I haven't explained well the situation. I'm not asking to connect 
to nodes *without* using a static IP address, but allowing Cassandra to 
determine the current public address at the time of connection.
Spark, for example, uses shell scripts for configuration, so the public 
IP (in AWS) can be assigned using the command `|curl 
http://169.254.169.254/latest/meta-data/public-ipv4|`, whatever it is at 
the time of boot.
Cassandra uses a yaml file for the main configuration, so this is 
impossibile to achieve. Basically I would like to make the client 
connect correctly on all nodes using their public IPs without being 
required to know them (the client would discover them dynamically while 
connecting).


Il 05/10/2015 00:55, Jonathan Haddad ha scritto:
> So you're not running the client in the same DC as your Cassandra 
> cluster.  In that case you'll need to be able to connect to the public 
> address of all the nodes.  Technically you could have a whitelist and 
> only connect to 1, I wouldn't recommend it.
>
> This is no different than any other database in that you would need a 
> public address to be able to connect to the servers from a machine not 
> in your datacenter.  How else would you connect to them if you don't 
> provide access?
>
> On Sun, Oct 4, 2015 at 6:35 PM Renato Perini <renato.perini@gmail.com 
> <mailto:renato.perini@gmail.com>> wrote:
>
>     Seems to be not the case when connecting to my (single) data
>     center using the java connector with a small client I have
>     developed for testing.
>     For the broadcast_rpc_address I have configured the local IP of
>     the nodes. The cluster works fine and nodes communicates fairly
>     well using their local IPs. When I connect to a node (let's say
>     node 1) from the outside using the java driver and the node's
>     public IP, the cluster discovery uses internal IPs for contacting
>     other nodes, leading to (obviously) errors.
>
>     As for AWS, Elastic IPs are free as long as they're associated to
>     an instance and the machines are up 24h/7. I have to shut down the
>     machines during the night for various reasons, so unfortunately
>     they're not totally free for my use case.
>
>
>
>     Il 05/10/2015 00:04, Jonathan Haddad ha scritto:
>>     Public IP?  No, not required unless you're running multiple DCs.
>>
>>     Where are you running a DC that IPs aren't cheap? If you're in
>>     AWS they're basically free (or at least the cheapest section of
>>     your bill by far)
>>
>>
>>
>>     On Sun, Oct 4, 2015 at 5:59 PM Renato Perini
>>     <renato.perini@gmail.com <mailto:renato.perini@gmail.com>> wrote:
>>
>>         Is cassandra really supposed to have a static public IP for
>>         each and
>>         single node in the cluster?
>>         This seems to be expensive (static IPs are nor free neither
>>         cheap),
>>         still the broadcast_rpc_address expects a static IP for client
>>         communications (load balancing, contact points, etc.)
>>         Is there some mechanism to determine a public IP at runtime?
>>
>>         Basically, I have nodes (machines) with dynamic public IPs
>>         and I cannot
>>         embed them in the cassandra.yaml file because of their
>>         dynamic nature
>>         (they change at each reboot).
>>         Any solution to this?
>>
>>         Thanks.
>>
>


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