NewSession sometimes panics when it should return an error

[miroswan]

Please answer these questions before submitting your issue. Thanks!

What version of Cassandra are you using?

3.0.9

What version of Gocql are you using?

v0.0.0-20190810123941-df4b9cc33030

What did you do?

gocql.NewSession panics when cassandra has not yet reported that it can receive connections

panic: no valid connect address for host: [HostInfo hostname="0.0.0.0" connectAddress="0.0.0.0" peer="<nil>" rpc_address="<nil>" broadcast_address="<nil>" preferred_ip="<nil>" connect_addr="0.0.0.0" connect_addr_source="invalid" port=9042 data_centre="" rack="" host_id="" version="v0.0.0" state=UP num_tokens=0]. Is your cluster configured correctly?

What did you expect to see?

I expect an error to be returned instead of a panic. This is where things seem to be breaking down:

https://github.com/gocql/gocql/blob/2274c8a9fab68a2be1c558b32eab48cb853163aa/session.go#L221

The ConnectAddress method does not return an error on failure. It panics. If this method returned an error in this condition, we could check for it here and bubble it up. This would allow me to keep checking until Cassandra is up instead of the thread crashing.

[miroswan]

I see now from the code that using 0.0.0.0 is not allowed. I've resolved this issue for myself, but I do think it's in our best interest to bubble up errrors to the caller of NewSession instead of causing a panic.

[tengu-alt]

@miroswan As I see the panic in this place is reasonable. The 0.0.0.0 should not be used, as it described here:
https://docs.datastax.com/en/cassandra-oss/2.1/cassandra/configuration/configCassandra_yaml_r.html

[joao-r-reis]

I actually think there's some merit in returning an error here instead of panic. Specially now that we allow custom host dialers so it is possible that the contact point is not even used

[tengu-alt]

I actually think there's some merit in returning an error here instead of panic. Specially now that we allow custom host dialers so it is possible that the contact point is not even used

I see. I will take care of it.

[OleksiienkoMykyta]

It was solved by #1858, @tengu-alt looks like you just forgot to add closes for the Issue, or there are should there be some additional patches provided?

[tengu-alt]

Looks like that, Issue should be closed.

[joao-r-reis]

v2.0.0-rc1 with the fix for this has been released, it would be great if users could try it out and provide feedback on it before 2.0.0 GA