Add method run_command to module_common.py

This adds a helper method that modules can call to execute a command via
subproces.  It takes two arguments: the command to run and
keyword options that control how the process is executed.  Supported
options are: fail_on_rc_non_zero, close_fds, and executable.
fail_on_rc_non_zero will call fail_json if the command fails.  If
args is a list, the command will be run with shell=False; otherwise, if
a string, it will be run with shell=True.  Otherwise, run_command() returns
the returncode, stdout, and stderr.

lib/ansible/module_common.py

@@ -677,6 +677,52 @@ class AnsibleModule(object):
                 self.set_context_if_different(src, context, False)
         os.rename(src, dest)
 
+    def run_command(self, args, **kwargs):
+        '''
+        Execute a command, returns rc, stdout, and stderr.
+        args is the command to run
+        If args is a list, the command will be run with shell=False.
+        Otherwise, the command will be run with shell=True when args is a string.
+        kwargs is a dict of keyword arguments:
+        - fail_on_rc_non_zero (boolean) Whether to call fail_json in case of
+                                        non zero RC.  Default is False.
+        - close_fds (boolean) See documentation for subprocess.Popen().
+                              Default is False.
+        - executable (string) See documentation for subprocess.Popen().
+                              Default is None.
+        '''
+        if isinstance(args, list):
+            kwargs['shell'] = False
+        elif isinstance(args, basestring):
+            kwargs['shell'] = True
+        else:
+            msg = "Argument 'args' to run_command must be list or string"
+            self.fail_json(rc=257, cmd=args, msg=msg)
+        if 'fail_on_rc_non_zero' not in kwargs:
+            kwargs['fail_on_rc_non_zero'] = False
+        if 'close_fds' not in kwargs:
+            kwargs['close_fds'] = False
+        if 'executable' not in kwargs:
+            kwargs['executable'] = None
+        rc = 0
+        msg = None
+        try:
+            cmd = subprocess.Popen(args,
+                                   executable=kwargs['executable'],
+                                   shell=kwargs['shell'],
+                                   close_fds=kwargs['close_fds'],
+                                   stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+            out, err = cmd.communicate()
+            rc = cmd.returncode
+        except (OSError, IOError), e:
+            self.fail_json(rc=e.errno, msg=str(e), cmd=args)
+        except:
+            self.fail_json(rc=257, msg=traceback.format_exc(), cmd=args)
+        if rc != 0 and kwargs['fail_on_rc_non_zero']:
+            msg = err.rstrip()
+            self.fail_json(cmd=args, rc=rc, stdout=out, stderr=err, msg=msg)
+        return (rc, out, err)
+
 # == END DYNAMICALLY INSERTED CODE ===
 
 """