inet.common.cluster.SSHCluster
==============================

.. py:class:: inet.common.cluster.SSHCluster(scheduler_hostname, worker_hostnames, nix_shell=None)

   Represents an SSH cluster. An SSH cluster is basically a set of network nodes, most often connected to a single LAN,
   all of which can login into each other using SSH passwordless login. The SSH cluster utilizes all network nodes with
   automatic and transparent load balancing as if it were a single computer.

   There are a couple of pitfalls that can prevent the SSH cluster from working correctly. If you encounter problems
   with the SSH cluster, make sure the following conditions are met:

   - scheduler and worker node hostnames can be resolved to IP addresses on all nodes
   - all nodes can SSH login into all other nodes (even themselves!) without any user interaction (no password is required)
   - the Python version and all required Python library versions are the same on all nodes
   - no firewall rule prevents the scheduler to connect to the workers
   - simulation projects are compiled both in release and debug versions

   Initializes a new SSH cluster object.

   :param scheduler_hostname: The hostname of the scheduler node.
   :type scheduler_hostname: string
   :param worker_hostnames: The hostnames of the worker nodes.
   :type worker_hostnames: list
   :param nix_shell: A Nix shell name that is used to execute tasks on the SSH cluster for repeatable results.
   :type nix_shell: string or None


   .. py:method:: run_gethostname(num_tasks=12)

      Collects the result of calling :py:func:`socket.gethostname` multiple times on the SSH cluster. This function is
      primarily useful to test the correct operation of the SSH cluster. The result should contain a permutation of the
      hostnames of all worker nodes.

      :param num_tasks: The number of times :py:func:`socket.gethostname` is called.
      :type num_tasks: int

      Returns (List):
          The hostname of worker nodes where :py:func:`socket.gethostname` was called.



   .. py:method:: start()

      Starts the SSH cluster and the dashboard web page.