Jonathan, I have some difficulties in understanding what you're talking
about. A client is a program connecting to a cassandra instance. All it
needs to know is an IP, a keyspace and a table to operate. My client is
nothing more than a simple textual version of a program like datastax
devcenter. No "same dc" concepts are involved for using it.
As for AWS, I'm not changing anything. The instances, as I said multiple
times, don't have an elastic ip, so the public IP is dynamic. This means
it changes automatically at every reboot.
Il 05/10/2015 02:22, Jonathan Haddad ha scritto:
If your client is in the same DC, then you shouldn't use *public* ip
addresses. If you're using a recent version of Cassandra you can just
set the listen_interface and rpc_interface to whatever network
interface you've got.
If you're really changing IPs when you reboot machines (I have no idea
why you'd do this, AWS definitely doesn't work this way) then I think
you're going to hit a whole set of other issues.
On Sun, Oct 4, 2015 at 7:10 PM Renato Perini <renato.per...@gmail.com
<mailto:renato.per...@gmail.com>> wrote:
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.per...@gmail.com <mailto:renato.per...@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.per...@gmail.com <mailto:renato.per...@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.
