ANSIBLE_SSH_USETTY configuration option (ansible#33148)

* Allow the user to circumvent adding -tt on ssh commands to help aid in
debugging ssh related problems.
* Move config to the plugin
* Set version_added
* Change yaml section to "connection"
* Fix ssh unit tests

examples/ansible.cfg

@@ -401,6 +401,10 @@
 # only be disabled if your sftp version has problems with batch mode
 #sftp_batch_mode = False
 
+# The -tt argument is passed to ssh when pipelining is not enabled because sudo 
+# requires a tty by default. 
+#use_tty = True
+
 [persistent_connection]
 
 # Configures the persistent connection timeout value in seconds.  This value is

lib/ansible/plugins/connection/ssh.py

@@ -185,6 +185,15 @@
         env: [{name: ANSIBLE_SCP_IF_SSH}]
         ini:
         - {key: scp_if_ssh, section: ssh_connection}
+      use_tty:
+        version_added: '2.5'
+        default: True
+        description: add -tt to ssh commands to force tty allocation
+        env: [{name: ANSIBLE_SSH_USETTY}]
+        ini:
+        - {key: usetty, section: ssh_connection}
+        type: boolean
+        yaml: {key: connection.usetty}
 '''
 
 import errno
@@ -957,7 +966,11 @@ def exec_command(self, cmd, in_data=None, sudoable=True):
 
         ssh_executable = self._play_context.ssh_executable
 
-        if not in_data and sudoable:
+        # -tt can cause various issues in some environments so allow the user
+        # to disable it as a troubleshooting method.
+        use_tty = self.get_option('use_tty')
+
+        if not in_data and sudoable and use_tty:
             args = (ssh_executable, '-tt', self.host, cmd)
         else:
             args = (ssh_executable, self.host, cmd)

test/units/plugins/connection/test_ssh.py

@@ -80,6 +80,8 @@ def test_plugins_connection_ssh_exec_command(self):
         conn._build_command.return_value = 'ssh something something'
         conn._run = MagicMock()
         conn._run.return_value = (0, 'stdout', 'stderr')
+        conn.get_option = MagicMock()
+        conn.get_option.return_value = True
 
         res, stdout, stderr = conn.exec_command('ssh')
         res, stdout, stderr = conn.exec_command('ssh', 'this is some data')
@@ -538,6 +540,8 @@ def test_retry_then_success(self, monkeypatch):
 
         self.conn._build_command = MagicMock()
         self.conn._build_command.return_value = 'ssh'
+        self.conn.get_option = MagicMock()
+        self.conn.get_option.return_value = True
 
         return_code, b_stdout, b_stderr = self.conn.exec_command('ssh', 'some data')
         assert return_code == 0
@@ -563,6 +567,8 @@ def test_multiple_failures(self, monkeypatch):
 
         self.conn._build_command = MagicMock()
         self.conn._build_command.return_value = 'ssh'
+        self.conn.get_option = MagicMock()
+        self.conn.get_option.return_value = True
 
         pytest.raises(AnsibleConnectionFailure, self.conn.exec_command, 'ssh', 'some data')
         assert self.mock_popen.call_count == 10
@@ -575,6 +581,8 @@ def test_abitrary_exceptions(self, monkeypatch):
 
         self.conn._build_command = MagicMock()
         self.conn._build_command.return_value = 'ssh'
+        self.conn.get_option = MagicMock()
+        self.conn.get_option.return_value = True
 
         self.mock_popen.side_effect = [Exception('bad')] * 10
         pytest.raises(Exception, self.conn.exec_command, 'ssh', 'some data')