start_background_process: Use sftp instead of scp for Windows VM

scp is used in the start_background_process() method to transfer the
script file to the host before executing it.

On Windows 11, OpenSSH doesn't support the scp legacy protocol which is
the only one supported by scp running on AlmaLinux 8, the distro behind
our Jenkins server.

Since AlmaLinux 8 and all of our Windows images support sftp, this patch
makes use of the sftp() function instead of the scp() one to transfer
the script file for VMs running any Windows version.
The destination path is also tweaked a bit and the file is sent to the
Windows Temp folder of the root user instead of /tmp. Since the script
is executed in the git-bash context of the root user, it will be located
as expected in /tmp, which is mapped on the Windows user Temp folder.

With this patch also comes a sftp_put() helper function taking source
and destination files as parameters like the scp() function does.

Signed-off-by: Thierry Escande <[email protected]>

lib/vm.py

@@ -100,6 +100,13 @@ def scp(self, src, dest, check=True, suppress_fingerprint_warnings=True, local_d
             local_dest=local_dest
         )
 
+    def sftp_put(self, src, dest, check=True, suppress_fingerprint_warnings=True):
+        cmd = "put {} {}".format(src, dest)
+        return commands.sftp(
+            self.ip, [cmd], check,
+            suppress_fingerprint_warnings=suppress_fingerprint_warnings
+        )
+
     def is_ssh_up(self):
         try:
             return self.ssh_with_result(['true']).returncode == 0
@@ -234,7 +241,10 @@ def start_background_process(self, cmd):
                 cmd + '\n'
             ])
             f.flush()
-            self.scp(f.name, script)
+            if self.is_windows:
+                self.sftp_put(f.name, script.replace("/tmp/", "/Users/root/AppData/Local/Temp/"))
+            else:
+                self.scp(f.name, script)
             # Use bash to run the script, to avoid being hit by differences between shells, for example on FreeBSD
             # It is a documented requirement that bash is present on all test VMs.
             self.ssh(['bash', script], background=True)