Executor cannot be started

Symptoms

Executor cannot be started

Error Messages

Error "Executor cannot be started, unable to ssh to <IP> with given credentials".

Cause

As evidenced by the error message, the executor is started via ssh. Therefore, if there are issues with the ssh connection, the Executor will not start.

Workaround Or Solution

Suggested troubleshooting methods

To troubleshoot this, first, test the ssh connection using the key that TigerGraph uses.

Note that depending on which node the error message references, you should test the ssh to that node. SSHing to localhost will also help to narrow down potential networking issues.

Note: if you installed TigerGraph via non-interactive installation and specified your own key, that should be used instead. You can see which key is used via the gssh command:

gssh | grep IdentityFile

Useful commands:

ssh -vi ~/.ssh/tigergraph_rsa tigergraph@<IP_ADDRESS>
ssh -vi ~/.ssh/tigergraph_rsa tigergraph@localhost
ping <IP_ADDRESS>
telnet <IP_ADDRESS> 22 # telnet nc and nmap commands all do the same thing
nc -vz <IP_ADDRESS> 22 # use whichever package you have available on your system
nmap -p 22 <IP_ADDRESS>

Recommended solution

Depending on the output of the ssh command, a variety of solutions are required.

  1. If the tigergraph user is subject to a password expiration policy, then this error will be raised during the ssh, and the password must be changed

  2. If the issue is due to the network configurations (firewall or issue communicating), then the ssh connection will fail before the ssh handshake begins

  3. If the ssh to localhost works but the IP address does not, confirm port 22 is open between nodes in the firewall

  4. If the key is not working, confirm that ssh via key is enabled in the sshd configuration and ensure that the key is present in ~/.ssh/authorized_keys