You've been talking about configuring static, public IPs. Public IPs are only needed if you want to connect to your Cassandra servers from a public network aka not from the same datacenter.
AWS instances don't get a new IP on rebooting. The instance doesn't shutdown when you tell a server to reboot, it just keeps running & keeps the same IP. You can connect to the internal address (192.168.x.x) or (10.x.x.x.) if you're on the same network. That's not a public IP. You don't have to hard code an address in your yaml, you can just the rpc_interface and set it to eth0 (or whatever AWS uses by default for server's NIC). Also, you know you can control IP addresses in a VPC, right? On Sun, Oct 4, 2015 at 8:31 PM Renato Perini <renato.per...@gmail.com> wrote: > 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> > 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> >> 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> >>> 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. >>>> >>> >>> >> >
