fixup: detect ssh availability when joining

crmsh/bootstrap.py

@@ -1789,7 +1789,14 @@ def join_ssh_with_ssh_agent(
 ):
     # As ssh-agent is used, the local_user does not have any effects
     shell = sh.SSHShell(local_shell, 'root')
-    # FIXME: detect the availability of ssh session
+    if not shell.can_run_as(seed_host, seed_user):
+        raise ValueError(f'Failed to login to {seed_user}@{seed_host}')
+    if seed_user != 'root' and 0 != shell.subprocess_run_without_input(
+            seed_host, seed_user, 'sudo true',
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+    ).returncode:
+        raise ValueError(f'Failed to sudo on {seed_user}@{seed_host}')
     authorized_key_manager = ssh_key.AuthorizedKeyManager(shell)
     for key in ssh_public_keys:
         authorized_key_manager.add(None, local_user, key)

crmsh/sh.py

@@ -207,14 +207,13 @@ def __init__(self, local_shell: LocalShell, local_user):
         self.local_user = local_user
 
     def can_run_as(self, host: typing.Optional[str], user: str) -> bool:
-        # FIXME: this method seems to return a different result from subprocess_run_without_input
-        if host is None or host == self.local_shell.hostname():
-            return self.local_shell.can_run_as(user)
-        else:
-            ssh_options = "-o StrictHostKeyChecking=no -o EscapeChar=none -o ConnectTimeout=15"
-            ssh_cmd = "ssh {} -T -o Batchmode=yes {}@{} true".format(ssh_options, user, host)
-            rc, output = self.local_shell.get_rc_and_error(self.local_user, ssh_cmd)
-            return rc == 0
+        result = self.subprocess_run_without_input(
+            host, user, 'true',
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+            start_new_session=True,
+        )
+        return 0 == result.returncode
 
     def get_rc_and_error(
             self,