Better dumping via private IP when bastion is not set

Previously this would always fail in a confusing way,
regardless of whether we had connectivity,
because we tried to connect to an empty-string host.

Now we are more explicit about the error,
and will at least try to connect directly.

cmd/kops/toolbox_dump.go

@@ -209,6 +209,9 @@ func RunToolboxDump(ctx context.Context, f commandutils.Factory, out io.Writer,
 			HostKeyCallback: ssh.InsecureIgnoreHostKey(),
 		}
 
+		klog.Infof("will SSH using username %q", sshConfig.User)
+		klog.Infof("ssh auth methods %v", sshConfig.Auth)
+
 		keyRing := agent.NewKeyring()
 		defer func(keyRing agent.Agent) {
 			_ = keyRing.RemoveAll()

pkg/dump/dumper.go

@@ -199,7 +199,12 @@ func (d *logDumper) dumpRegistered(ctx context.Context, node *corev1.Node) error
 	if publicIP != "" {
 		return d.dumpNode(ctx, node.Name, publicIP, false)
 	} else {
-		return d.dumpNode(ctx, node.Name, privateIP, true)
+		useBastion := true
+		if !d.sshClientFactory.HasBastion() {
+			klog.Warningf("no bastion address set, will attempt to connect to node %s directly via private IP %v", node.Name, privateIP)
+			useBastion = false
+		}
+		return d.dumpNode(ctx, node.Name, privateIP, useBastion)
 	}
 }
 
@@ -274,7 +279,12 @@ type sshClient interface {
 
 // sshClientFactory is an interface abstracting to a node over SSH
 type sshClientFactory interface {
+	// Dial creates a new sshClient
 	Dial(ctx context.Context, host string, useBastion bool) (sshClient, error)
+
+	// HasBastion returns true if the sshClientFactory has a bastion configured.
+	// Calling Dial with useBastion=true will return an error if there is no bastion.
+	HasBastion() bool
 }
 
 // logDumperNode holds state for a particular node we are dumping
@@ -540,21 +550,31 @@ type sshClientFactoryImplementation struct {
 
 var _ sshClientFactory = &sshClientFactoryImplementation{}
 
+// HasBastion implements sshClientFactory::HasBastion
+func (f *sshClientFactoryImplementation) HasBastion() bool {
+	return f.bastion != ""
+}
+
 // Dial implements sshClientFactory::Dial
 func (f *sshClientFactoryImplementation) Dial(ctx context.Context, host string, useBastion bool) (sshClient, error) {
-	var addr string
+	addr := host
 	if useBastion {
+		if f.bastion == "" {
+			return nil, fmt.Errorf("bastion is not set, but useBastion is true")
+		}
 		addr = f.bastion
-	} else {
-		addr = host
+	}
+
+	if addr == "" {
+		return nil, fmt.Errorf("host is empty")
 	}
 	addr = net.JoinHostPort(addr, "22")
 	d := net.Dialer{
 		Timeout: 5 * time.Second,
 	}
 	conn, err := d.DialContext(ctx, "tcp", addr)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("error dialing tcp %s: %w", addr, err)
 	}
 
 	// We have a TCP connection; we will force-close it to support context cancellation