updates for basic working distrbuted network using fabric

daemon/core/emulator/distributed.py

@@ -0,0 +1,27 @@
+import logging
+
+from core.errors import CoreCommandError
+
+
+def remote_cmd(server, cmd, env=None):
+    """
+    Run command remotely using server connection.
+
+    :param fabric.connection.Connection server: remote server node will run on,
+        default is None for localhost
+    :param str cmd: command to run
+    :param dict env: environment for remote command, default is None
+    :return: stdout when success
+    :rtype: str
+    :raises CoreCommandError: when a non-zero exit status occurs
+    """
+    logging.info("remote cmd server(%s): %s", server, cmd)
+    if env is None:
+        result = server.run(cmd, hide=False)
+    else:
+        result = server.run(cmd, hide=False, env=env, replace_env=True)
+    if result.exited:
+        raise CoreCommandError(
+            result.exited, result.command, result.stdout, result.stderr
+        )
+    return result.stdout.strip()