Fix std.ssh "password" parameter

Fixes the bug where calling std.ssh action without "password" input was resulting in error.
Closes-bug: #1756272

Change-Id: I5f7af13326933658014a9c42c495d779bec7f14f

doc/source/user/wf_lang_v2.rst

@@ -1077,11 +1077,10 @@ Input parameters:
 -  **username** - User name to authenticate on the host. *Required*.
 -  **password** - User password to to authenticate on the host. *Optional*.
 -  **private_key_filename** - Private key file name which will be used for
-   authentication on remote host.
-
-All private keys should be on executor host in **<home-user-directory>/.ssh/**.
-**<home-user-directory>** should refer to user directory under which service is
-running. *Optional*.
+   authentication on remote host. All private keys should be on the executor
+   host in **<home-user-directory>/.ssh** directory or absolute path of
+   the key should be provided. The file needs to be accessible
+   for the user account running the executor. *Optional*.
 
 **NOTE**: Authentication using key pairs is supported, key should be
 on Mistral Executor server machine.

mistral/actions/std_actions.py

@@ -347,7 +347,7 @@ class SSHAction(actions.Action):
         return ssh_utils.execute_command
 
     def __init__(self, cmd, host, username,
-                 password=None, private_key_filename=None):
+                 password="", private_key_filename=None):
         super(SSHAction, self).__init__()
 
         self.cmd = cmd
@@ -396,8 +396,7 @@ class SSHAction(actions.Action):
             return raise_exc(parent_exc=e)
 
     def test(self, context):
-        # TODO(rakhmerov): Implement.
-        return None
+        return json.dumps(self.params)
 
 
 class SSHProxiedAction(SSHAction):

mistral/tests/unit/actions/test_std_ssh_action.py

@@ -0,0 +1,36 @@
+#    Copyright 2018 Nokia Networks.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import json
+
+from mistral.actions import std_actions as std
+from mistral.tests.unit import base
+
+
+class SSHActionTest(base.BaseTest):
+
+    def test_default_inputs(self):
+        cmd = "echo -n ok"
+        host = "localhost"
+        username = "mistral"
+        action = std.SSHAction(cmd, host, username)
+        mock_ctx = None
+
+        stdout = action.test(mock_ctx)
+        params = json.loads(stdout)
+
+        self.assertEqual("", params['password'], "Password does not match.")
+        self.assertIsNone(
+            params['private_key_filename'],
+            "private_key_filename is not None.")