kubernetes/minikube

SSH driver: --ssh-user argument seems to be ignored

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#12,632 opened on Sep 30, 2021

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Description

Steps to reproduce the issue: minikube -p vm-cloud-k8s start --driver=ssh --native-ssh=false --ssh-user=vrubiolo --ssh-ip-address=vm-cloud --ssh-key=~/.ssh/id_rsa-vm_cloud --alsologtostderr -v=4 2>&1 | tee minikube.log

We can see futher down that minikube tries to connect using the root user, bypassing the --ssh-user option:

* Updating the running ssh "vm-cloud-k8s" bare metal machine ...
I0930 16:05:21.592604  898636 machine.go:88] provisioning docker machine ...
I0930 16:05:21.592842  898636 main.go:130] libmachine: Waiting for SSH to be available...
I0930 16:05:21.592906  898636 main.go:130] libmachine: Getting to WaitForSSH function...
I0930 16:05:21.593313  898636 main.go:130] libmachine: Using SSH client type: external
I0930 16:05:21.593462  898636 main.go:130] libmachine: &{[-F /dev/null -o ConnectionAttempts=3 -o ConnectTimeout=10 -o ControlMaster=no -o ControlPath=none -o LogLevel=quiet -o PasswordAuthentication=no -o ServerAliveInterval=60 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null root@vm-cloud -p 22] /usr/bin/ssh <nil>}
I0930 16:05:21.593526  898636 main.go:130] libmachine: About to run SSH command:
exit 0
I0930 16:05:21.703314  898636 main.go:130] libmachine: SSH cmd err, output: exit status 255: 
I0930 16:05:21.703385  898636 main.go:130] libmachine: Error getting ssh command 'exit 0' : ssh command error:
command : exit 0
err     : exit status 255

The machine does not allow SSH using the root account, which is why this fails. One can see this via the SSH command in verbose mode (this is why I used the external SSH binary):

$ /usr/bin/ssh -F /dev/null -o ConnectionAttempts=3 -o ConnectTimeout=10 -o ControlMaster=no -o ControlPath=none -o LogLevel=verbose -o PasswordAuthentication=no -o ServerAliveInterval=60 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null root@vm-cloud -p 22
Warning: Permanently added 'vm-cloud' (ED25519) to the list of known hosts.
root@vm-cloud: Permission denied (publickey).

Workaround Enable root account over SSH (if possible) for provisioning to continue.

Run minikube logs --file=logs.txt and drag and drop the log file into this issue minikube.log

This is minikube v1.23.1 on Fedora 34

Contributor guide

Tech stack
go
Domain
devops
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Go programmingSSH basicsminikube internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Investigate how the ssh user flag is handled in the SSH driver. Start by examining the driver code in pkg/minikube/drivers/ssh/ and the flag definitions in cmd/minikube/cmd/start.go. Trace the flow from flag parsing to the SSH command construction, focusing on where the username parameter is passed. The issue shows that the external SSH command uses 'root' instead of the specified user, so look for where the username is overridden or defaulted. Review the comments in the issue for any additional clues.
SSH driver: --ssh-user argument seems to be ignored · kubernetes/minikube#12632 | Good First Issue