.. _remote_execution_in_clusters:

Remote Execution in Clusters
----------------------------

.. index:: cluster;cluster run
.. index:: cluster;cluster job


When commands are run on a cluster, a number of options are available to 
specify the nodes on which the commands can be run. 

There is a *<where>* clause: **cluster run <where>**. 

The clause can take:

* *role*  - the role of the node: ``application``, ``database``, ``webproxy``
* ``all`` - all the roles, in other words, the entire cluster
* ``notme`` - all nodes except the one the command is run on
* ``<data center name>`` - all nodes in the data center
* ``<nodename|IP>`` - the hostname or IP address of the node.

For example:

* **cluster run database app start mongodb** will restart the 
  mongodb service on all database nodes.
* **cluster run all app status** will display the app status 
  of all nodes on the cluster.
* **cluster run notme system shutdown** would issue the command to shut down
  all nodes except the one the command is run on.

.. important::
   In a cluster, reboot and shutdown of the entire cluster should be done on each node and not
   with the **cluster run all** command. 

Sometimes there are long-running processes running on a server.  To display 
such jobs, use the **cluster job list** command.

.. note::
   The **cluster job list** command is not available on a web proxy node.

It is also possible to re-attach to those jobs to see the output, using 
**cluster job reconnect <pid>**.