a new module for SSH utilities

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>

diff --git a/ceph_deploy/util/ssh.py b/ceph_deploy/util/ssh.py
new file mode 100644 (file)
index 0000000..6bcca04
--- /dev/null
+++ b/ceph_deploy/util/ssh.py
@@ -0,0 +1,32 @@
+import logging
+from ceph_deploy.lib.remoto import process
+from ceph_deploy.lib.remoto.connection import needs_ssh
+from ceph_deploy.connection import get_local_connection
+
+
+def can_connect_passwordless(hostname):
+    """
+    Ensure that current host can SSH remotely to the remote
+    host using the ``BatchMode`` option to prevent a password prompt.
+
+    That attempt will error with an exit status of 255 and a ``Permission
+    denied`` message.
+    """
+    # Ensure we are not doing this for local hosts
+    if not needs_ssh(hostname):
+        return True
+
+    logger = logging.getLogger(hostname)
+    with get_local_connection(logger) as conn:
+        # Check to see if we can login, disabling password prompts
+        command = ['ssh', '-CT', '-o', 'BatchMode=yes', hostname]
+        out, err, retval = process.check(conn, command, stop_on_error=False)
+        expected_error = 'Permission denied (publickey,password)'
+        has_key_error = False
+        for line in err:
+            if expected_error in line:
+                has_key_error = True
+
+        if retval == 255 and has_key_error:
+            return False
+    return True