What should I try when cassandra appears to be running and listening but cqlsh can't connect?

Question

I'm new to Cassandra and was trying it out. Despite Cassandra apparently running and listening (according to lsof) I can't connect to it. sudo systemctl status cassandr also reports active (running).

$ sudo lsof -Pnl +M -i4 
COMMAND  PID     USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
(omitting unrelated services - nothing here about cassandra)

$ sudo lsof -Pnl +M -i6
COMMAND   PID     USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
sshd      752        0    4u  IPv6  16234      0t0  TCP *:22 (LISTEN)
java    23659      300   68u  IPv6 158110      0t0  TCP 127.0.0.1:7199 (LISTEN)
java    23659      300   69u  IPv6 158122      0t0  TCP 127.0.0.1:36921 (LISTEN)
java    23659      300   84u  IPv6 158212      0t0  TCP 127.0.0.1:9160 (LISTEN)
java    23659      300  151u  IPv6 158205      0t0  TCP 127.0.0.1:7000 (LISTEN)



$ sudo nodetool status
Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address    Load       Owns (effective)  Host ID                               Token                                    Rack
UN  127.0.0.1  125.98 KiB  100.0%            e0bbc831-8686-43a6-b99c-8ea5596c8581  3840369556391221198                      rack1

For Nix users who might be reading this (also easy to grasp for non-Nix users), my config is just:

  services.cassandra = {
    enable = true;
    listenAddress = "127.0.0.1";
    rpcAddress = "127.0.0.1";
  };

The error I get is:

$ cqlsh 127.0.0.1 9160
Connection error: ('Unable to connect to any servers', {'127.0.0.1': error(111, "Tried connecting to [('127.0.0.1', 9160)]. Last error: Connection refused")})

Answer 1

Try using native_transport_port 9042 rather than rpc_port 9160 while connecting though cqlsh.

cqlsh 127.0.0.1 9042

If you still get this error then check your Cassandra configuration as per link this and this

Answer 2

I should have checked on the nixpks issue tracker, as I found the answer there; I needed:

extraConfig = {
  start_native_transport = true;
};