How do I properly configure Cassandra in EC2 to connect to it?

Question

I have an AWS EC2 instance with Centos 8 .

Inside this instance, I have successfully installed the Cassandra ( 3.11.10 ) database.

Inside this database, I have successfully created keyspace via this CQL query:

create keyspace if not exists dev_keyspace with replication={'class': 'SimpleStrategy', 'replication_factor' : 2};

Then I edited configurion file ( /etc/cassandra/default.conf/cassandra.yaml ):

cluster_name: "DevCluster"
seeds: <ec2_private_ip_address>
listen_address: <ec2_private_ip_address>
start_rpc: true
rpc_address: 0.0.0.0
broadcast_rpc_address: <ec2_private_ip_address>
endpoint_snitch: Ec2Snitch

After that, restarted database:

Datacenter: eu-central
======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address                   Load       Tokens       Owns (effective)  Host ID                               Rack
UN  <ec2_private_ip_address>  75.71 KiB  256          100.0%            XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX  1a

When I try to connect to the Cassandra database with such credentials it raise an error:

host: <ec2_public_ip_address>
port: 9042
keyspace: dev_keyspace
username: cassandra (default)
password: cassandra (default)

ERROR :

All host(s) tried for query failed (tried: /<ec2_private_ip_address>:9042 (com.datastax.driver.core.exceptions.TransportException: [/<ec2_private_ip_address>:9042] Cannot connect))

What did I forget to configure? Let me know if you need more information.

Answer 1

You won't be able to access your cluster remotely because you've configured Cassandra to only listen for clients on the private IP with this setting:

broadcast_rpc_address: <ec2_private_ip_address>

For the node to accept requests from external clients, you need to set the following in cassandra.yaml :

listen_address: private_ip
rpc_address: public_ip

Note that you don't need to set the broadcast RPC address. You will need to restart Cassandra for the changes to take effect.

You will also need to define a security group with inbound rules on the AWS Management Console to allow ingress to your EC2 instances on port 9042 . Cheers!