Cluster can't connect to redshift

[Danh_Hoa]

I'm trying to connect to redshift with redshift-connector module, but it get 'Connection refused' error, redshift cluster and ec2 cluster are in the same VPC, security group of redshift cluster is open with inbound from VPC's IP range, i can connect from other EC2 instance which i have create by my self before, so what's happened with my databricks cluster?

[Kaniz_Fatma]

Hi @Danh_Hoa , There could be several reasons why you are unable to connect to your Redshift cluster from your Databricks cluster:

1. **VPC Peering**: It might be possible that VPC peering is misconfigured. You need to validate the peering configuration and make sure the peering connections from requestor and acceptor VPC IDs are correct. Also, confirm that the peering connection is active from the target VPC.

2. **Security Groups and NACLs**: The corresponding port might be blocked at the network component level, due to Security Groups (SG), Network Access Control Lists (NACL), or other routing issues. Check the NACL attached to the subnets and allow all traffic to Redshift, for both inbound and outbound rules. Also, make sure that port 5439 (Redshift) is open to the target security group that is attached to Redshift.

3. **DNS Issues**: There might be a DNS issue. Ensure that the Redshift cluster is up, the hostname is typed correctly, and the Redshift cluster IP address works, in place of the hostname.