Paramiko get stdout from connection object (not exec_command)

Question

I'm writing a script that uses paramiko to ssh onto several remote hosts and run a few checks. Some hosts are setup as fail-overs for others and I can't determine which is in use until I try to connect. Upon connecting to one of these 'inactive' hosts the host will inform me that you need to connect to another 'active' IP and then close the connection after n seconds. This appears to be written to the stdout of the SSH connection/session (i.e. it is not an SSH banner).

I've used paramiko quite a bit, but I'm at a loss as to how to get this output from the connection, exec_command will obviously give me stdout and stderr, but the host is outputting this immediately upon connection, and it doesn't accept any other incoming requests/messages. It just closes after n seconds.

I don't want to have to wait until the timeout to move onto the next host and I'd also like to verify that that's the reason for not being able to connect and run the checks, otherwise my script works as intended.

Any suggestions as to how I can capture this output, with or without paramiko, is greatly appreciated.

Answer 1

I figured out a way to get the data, it was pretty straight forward to be honest, albeit a little hackish. This might not work in other cases, especially if there is latency, but I could also be misunderstanding what's happening:

When the connection opens, the server spits out two messages, one saying it can't chdir to a particular directory, then a few milliseconds later it spits out another message stating that you need to connect to the other IP. If I send a command immediately after connecting (doesn't matter what command), exec_command will interpret this second message as the response. So for now I have a solution to my problem as I can check this string for a known message and change the flow of execution.

However, if what I describe is accurate, then this may not work in situations where there is too much latency and the 'test' command isn't sent before the server response has been received.

As far as I can tell (and I may be very wrong), there is currently no proper way to get the stdout stream immediately after opening the connection with paramiko. If someone knows a way, please let me know.