.. _delta-proxy-information:

.. _delta-proxy-intro:

===================
Delta proxy minions
===================

Welcome to the delta proxy minion installation guide. This installation
guide explains the process for installing and using delta proxy minion
which is available beginning in version 3004.

This guide is intended for system and network administrators with the general
knowledge and experience required in the field. This guide is also intended for
users that have ideally already tested and used standard Salt proxy minions in
their environment before deciding to move to a delta proxy minion environment.
See `Salt proxy minions <https://docs.saltproject.io/en/latest/topics/proxyminion/index.html>`_ for more information.

.. Note::
    If you have not used standard Salt proxy minions before, consider testing
    and deploying standard Salt proxy minions in your environment first.


Proxy minions vs. delta proxy minions
=====================================
Salt can target network devices through `Salt proxy minions
<https://docs.saltproject.io/en/latest/topics/proxyminion/index.html>`_,
Proxy minions allow you to control network devices that, for whatever reason,
cannot run the standard Salt minion. Examples include:

* Network gear that has an API but runs a proprietary operating system
* Devices with limited CPU or memory
* Devices that could run a minion but will not for security reasons

A proxy minion acts as an intermediary between the Salt master and the
device it represents. The proxy minion runs on the Salt master and then
translates commands from the Salt master to the device as needed.

By acting as an intermediary for the actual minion, proxy minions eliminate
the need to establish a constant connection from a Salt master to a minion. Proxy
minions generally only open a connection to the actual minion when necessary.

Proxy minions also reduce the amount of CPU or memory the minion must spend
checking for commands from the Salt master. Proxy minions use the Salt master's CPU
or memory to check for commands. The actual minion only needs to use CPU or
memory to run commands when needed.

.. Note::
    For more information about Salt proxy minions, see:

    * `Salt proxy minions
      <https://docs.saltproject.io/en/latest/topics/proxyminion/index.html>`_

    * `Salt proxy modules
      <https://docs.saltproject.io/en/latest/ref/proxy/all/index.html#all-salt-proxy>`_


When delta proxy minions are needed
-----------------------------------
Normally, you would create a separate instance of proxy minion for each device
that needs to be managed. However, this doesn't always scale well if you have
thousands of devices. Running several thousand proxy minions can require a lot
of memory and CPU.

A delta proxy minion can solve this problem: it makes it possible to run one
minion that acts as the intermediary between the Salt master and the many network
devices it can represent. In this scenario, one device (the delta proxy minion
on the Salt master) runs several proxies. This configuration boosts performance and
improves the overall scalability of the network.


Key terms
=========
The following lists some important terminology that is used throughout this
guide:

.. list-table::
  :widths: 25 75
  :header-rows: 1

  * - Term
    - Definition

  * - Salt master
    - The Salt master is a central node running the Salt master server.
      The Salt master issues commands to minions.

  * - minion
    - Minions are nodes running the Salt minion service. Minions listen
      to commands from a Salt master and perform the requested tasks, then return
      data back to the Salt master as needed.

  * - proxy minion
    - A Salt master that is running the proxy-minion service. The proxy minion
      acts as an intermediary between the Salt master and the device it represents.
      The proxy minion runs on the Salt master and then translates commands from
      the Salt master to the device. A separate instance of proxy minion is
      needed for each device that is managed.

  * - delta proxy minion
    - A Salt master that is running the delta proxy-minion service. The
      delta proxy minion acts as the intermediary between the Salt master and the
      many network devices it can represent. Only one instance of the delta
      proxy service is needed to run several proxies.

  * - control proxy
    - The control proxy runs on the Salt master. It manages a list of devices and
      issues commands to the network devices it represents. The Salt master needs
      at least one control proxy, but it is possible to have more than one
      control proxy, each managing a different set of devices.

  * - managed device
    - A device (such as Netmiko) that is managed by proxy minions or by a
      control proxy minion. The proxy minion or control proxy only creates
      a connection to the actual minion it needs to issue a command.

  * - pillar file
    - Pillars are structures of data (files) defined on the Salt master and passed
      through to one or more minions when the minion needs access to the
      pillar file. Pillars allow confidential, targeted data to be securely sent
      only to the relevant minion. Because all configurations for
      delta proxy minions are done on the Salt master (not on the minions), you
      use pillar files to configure the delta proxy-minion service.

  * - top file
    - The top file is a pillar file that maps which states should be applied to
      different minions in certain environments.

.. _delta-proxy-preinstall:

Pre-installation
================

Before you start
----------------
Before installing the delta proxy minion, ensure that:

* Your network device and firmware are supported.
* The Salt master that is acting as the control proxy minion has network
  access to the devices it is managing.
* You have installed, configured, and tested standard Salt proxy minions in
  your environment before introducing delta proxy minions into your
  environment.


Install or upgrade Salt
-----------------------
Ensure your Salt masters are running at least Salt version 3004. For instructions
on installing or upgrading Salt, see `repo.saltproject.io
<http://repo.saltproject.io/>`_. For RedHat systems, see `Install or Upgrade Salt
<https://enterprise.saltproject.io/en/latest/docs/install-salt.html>`_.



.. _delta-proxy-install:

Installation
============

Before you begin the delta proxy minion installation process, ensure you
have read and completed the :ref:`delta-proxy-preinstall` steps.


Overview of the installation process
------------------------------------
Similar to proxy minions, all the delta proxy minion configurations are done
on the Salt master rather than on the minions that will be managed. The
installation process has the following phases:

#. `Configure the master to use delta proxy`_ - Create a
   configuration file on the Salt master that defines its proxy settings.
#. `Create a pillar file for each managed device`_ - Create a
   pillar file for each device that will be managed by the delta proxy minion
   and reference these minions in the top file.
#. `Create a control proxy configuration file`_ - Create a control proxy file
   that lists the devices that it will manage. Then, reference this file in the
   top file.
#. `Start the delta proxy minion`_ - Start the delta proxy-minion service and
   validate that it has been set up correctly.


Configure the master to use delta proxy
---------------------------------------
In this step, you'll create a configuration file on the Salt master that defines
its proxy settings. This is a general configuration file that tells the Salt master
how to handle all proxy minions.

To create this configuration:

#. On the Salt master, navigate to the ``/etc/salt`` directory. In this directory,
   create a file named ``proxy`` if one doesn't already exist.

#. Open the file in your preferred editor and add the following configuration
   information:

   .. code-block:: yaml

       # Use delta proxy metaproxy
       metaproxy: deltaproxy

       # Disable the FQDNS grain
       enable_fqdns_grains: False

       # Enabled multprocessing
       multiprocessing: True

   .. Note::
       See the following section about `delta proxy configuration options`_ for
       a more detailed description of these configuration options.

#. Save the file.

Your Salt master is now configured to use delta proxy. Next, you need to
`Create a pillar file for each managed device`_.


Delta proxy configuration options
---------------------------------
The following table describes the configuration options used in the delta
proxy configuration file:

.. list-table::
  :widths: 25 75
  :header-rows: 1

  * - Field
    - Description

  * - metaproxy
    - Set this configuration option to ``deltaproxy``. If this option is set to
      ``proxy`` or if this line is not included in the file, the Salt master will
      use the standard proxy service instead of the delta proxy service.

  * - enable_fqdns_grains
    - If your router does not have the ability to use Reverse DNS lookup to
      obtain the Fully Qualified Domain Name (fqdn) for an IP address, you'll
      need to change the ``enable_fqdns_grains`` setting in the pillar
      configuration file to ``False`` instead.

  * - multiprocessing
    - Multi-processing is the ability to run more than one task or process at
      the same time. A delta proxy minion has the ability to run with
      multi-processing turned off.

      If you plan to run with multi-processing enabled, you should also enable
      the ``skip_connect_on_init`` setting to ``True``.

  * - skip_connect_on_init
    - This setting tells the control proxy whether or not it should make a
      connection to the managed device when it starts. When set to ``True``, the
      delta proxy minion will only connect when it needs to issue commands to
      the managed devices.


Create a pillar file for each managed device
--------------------------------------------
Each device that needs to be managed by delta proxy needs a separate pillar
file on the Salt master. To create this file:

#. Navigate to the ``/srv/pillar`` directory.

#. In this directory create a new pillar file for a minion. For example,
   ``my_managed_device_pillar_file_01.sls``.

#. Open the new file in your preferred editor and add the necessary
   configuration information for that minion and your environment. The
   following is an example pillar file for a Netmiko device:

   .. code-block:: yaml

       proxy:
         proxytype: netmiko
         device_type: arista_eos
         host: 192.0.2.1
         username: myusername
         password: mypassword
         always_alive: True


   .. Note::
      The available configuration options vary depending on the proxy type (in
      other words, the type of device it is). To read a detailed explanation of
      the configuration options, refer to the proxy module documentation for
      the type of device you need to manage. See:

      * `Salt proxy modules
        <https://docs.saltproject.io/en/latest/ref/proxy/all/index.html#all-salt-proxy>`_
      * `Netmiko Salt proxy module
        <https://docs.saltproject.io/en/latest/ref/proxy/all/salt.proxy.netmiko_px.html#module-salt.proxy.netmiko_px>`_

#. Save the file.

#. In an editor, open the top file: ``/srv/pillar/top.sls``.

#. Add a section to the top file that indicates the minion ID of the device
   that will be managed. Then, list the name of the pillar file you created in
   the previous steps. For example:

   .. code-block:: yaml

       my_managed_device_minion_ID:
         - my_managed_device_pillar_file_01

#. Repeat the previous steps for each minion that needs to be managed.

You've now created the pillar file for the minions that will be managed by the
delta proxy minion and you have referenced these files in the top file.
Proceed to the next section.


Create a control proxy configuration file
-----------------------------------------
On the Salt master, you'll need to create or edit a control proxy file for each
control proxy. The control proxy manages several devices and issues commands to
the network devices it represents. The Salt master needs at least one control
proxy, but it is possible to have more than one control proxy, each managing a
different set of devices.

To configure a control proxy, you'll create a file that lists the minion IDs
of the minions that it will manage. Then you will reference this control proxy
configuration file in the top file.

To create a control proxy configuration file:

#. On the Salt master, navigate to the ``/srv/pillar`` directory. In this
   directory, create a new proxy configuration file. Give this file a
   descriptive name, such as ``control_proxy_01_configuration.sls``.

#. Open the file in your preferred editor and add a list of the minion IDs for
   each device that needs to be managed. For example:

   .. code-block:: yaml

       proxy:
         proxytype: deltaproxy
         ids:
           - my_managed_device_01
           - my_managed_device_02
           - my_managed_device_03

#. Save the file.

#. In an editor, open the top file: ``/srv/pillar/top.sls``.

#. Add a section to the top file that indicates references the delta proxy
   control proxy. For example:

   .. code-block:: yaml

       base:
         my_managed_device_minion_01:
           - my_managed_device_pillar_file_01
         my_managed_device_minion_02:
           - my_managed_device_pillar_file_02
         my_managed_device_minion_03:
           - my_managed_device_pillar_file_03
         delta_proxy_control:
           - control_proxy_01_configuration

#. Repeat the previous steps for each control proxy if needed.


Now that you have created the necessary configurations, proceed to the next
section.


Start the delta proxy minion
----------------------------
After you've successfully configured the delta proxy minion, you need to
start the proxy minion service for each managed device and validate that it is
working correctly.

.. Note::
    This step explains the process for starting a single instance of a
    delta proxy minion. Because starting each minion individually can
    potentially be very time-consuming, most organizations use a script to start
    their delta proxy minions since there are typically many devices being
    managed. Consider implementing a similar script for your environment to save
    time in deployment.

To start a single instance of a delta proxy minion and test that it is
configured correctly:

#. In the terminal for the Salt master, run the following command, replacing the
   placeholder text with the actual minion ID:

   .. code-block:: bash

       sudo salt-proxy --proxyid=my_managed_device_minion_ID


#. To test the delta proxy minion, run the following ``test.version`` command
   on the Salt master and target a specific minion. For example:

   .. code-block:: bash

       salt my_managed_device_minion_ID test.version

   This command returns an output similar to the following:

   .. code-block:: bash

       local:
           3004

After you've successfully started the delta proxy minions and verified that
they are working correctly, you can now use these minions the same as standard
proxy minions.

.. _delta-proxy-additional-resources:

Additional resources
====================

This reference section includes additional resources for delta proxy minions.

For reference, see:

* `Salt proxy minions
  <https://docs.saltproject.io/en/latest/topics/proxyminion/index.html>`_

* `Salt proxy modules
  <https://docs.saltproject.io/en/latest/ref/proxy/all/index.html#all-salt-proxy>`_

* `Netmiko Salt proxy module
  <https://docs.saltproject.io/en/latest/ref/proxy/all/salt.proxy.netmiko_px.html#module-salt.proxy.netmiko_px>`_

