Add Ironic User Guide

Add a User guide, Initial chapters to cover introduction, architecture
diagrams, terminology for Ironic service.

Change-Id: I08faac6204aa412e330362133eb14241f3c21b34

doc/source/deploy/userguide.rst

@@ -0,0 +1,110 @@
+
+=======================
+Introduction to Ironic
+=======================
+|
+     Ironic is an OpenStack project which provisions physical hardware as opposed to virtual machines.
+     Ironic provides several reference drivers which leverage common technologies like PXE and IPMI, to
+     cover a wide range of hardware. Ironic's pluggable driver architecture also allows vendor-specific
+     drivers to be added for improved performance or functionality not provided by reference drivers.
+|
+     If one thinks of traditional hypervisor functionality (e.g., creating a VM, enumerating virtual devices, managing
+     the power state, loading an OS onto the VM, and so on), then Ironic may be thought of as a hypervisor API gluing
+     together multiple drivers, each of which implement some portion of that functionality with respect to physical hardware.
+|
+|
+     Openstack's Ironic project makes physical servers as easy to provision as virtual machines in cloud, which in turn will
+     open up new avenues for enterprises and service providers.
+|
+     Ironic's driver will replace the Nova "bare metal" driver of Grizzly, Havana and Icehouse releases. It is targeting inclusion
+     in the OpenStack Juno release. See https://wiki.openstack.org/wiki/Baremetal for more information.
+|
+|
+Why Provision Bare Metal
+==========================
+|
+     Here are a few use-cases for bare metal (physical server) provisioning in cloud; there are doubtless many more interesting ones.
+|
+|
+        High-performance computing clusters
+|
+        Computing tasks that require access to hardware devices which can't be virtualized
+|
+        Database hosting (some databases run poorly in a hypervisor)
+|
+        Single tenant, dedicated hardware for performance, security, dependability and other regulatory requirements
+|
+        Or, rapidly deploying a cloud infrastructure
+|
+|
+Conceptual Architecture
+========================
+|
+     The following diagram shows the relationships and how all services come into play during the provisioning of a
+     physical server.
+|
+.. figure:: ../images/conceptual_architecture.gif
+   :alt: ConceptualArchitecture
+|
+|
+Logical Architecture
+=====================
+|
+     The Ironic service is composed of the following components,
+|
+|
+     A RESTful API service, by which operators and other services may interact with the managed bare metal servers.
+|
+|
+     A Conductor service, which does the bulk of the work. Functionality is exposed via the API service.
+     The Conductor and API services communicate via RPC.
+|
+|
+     A Message Queue
+|
+|
+     A Database for storing the state of the Conductor and Drivers.
+|
+|
+
+.. figure:: ../images/logical_architecture.gif
+   :alt: Logical Architecture
+|
+|
+Key Technologies for Bare Metal Hosting
+===========================================
+|
+PXE
+-----
+|
+Preboot Execution Environment (PXE) is part of the Wired for Management (WfM) specification developed by Intel and Microsoft.
+The PXE enables system's BIOS and network interface card (NIC) to bootstrap a computer from the network in place of a disk. Bootstrapping is the process by which a system loads the OS into local memory so that it can be executed by the processor.
+This capability of allowing a system to boot over a network simplifies server deployment and server management for administrators.
+
+|
+DHCP
+------
+|
+Dynamic Host Configuration Protocol (DHCP) is a standardized networking protocol used on Internet Protocol (IP) networks for dynamically distributing network configuration parameters, such as IP addresses for interfaces and services.
+Using PXE, the BIOS uses DHCP to obtain an IP address for the network interface and to locate the server that stores the network bootstrap program (NBP).
+
+|
+NBP
+------
+|
+Network Bootstrap Program (NBP) is equivalent to GRUB (GRand Unified Bootloader) or LILO (LInux LOader) - loaders which are traditionally used in local booting. Like the boot program in a hard drive environment, the NBP is responsible for loading the OS kernel into memory so that the OS can be bootstrapped over a network.
+
+|
+TFTP
+------
+|
+        Trivial File Transfer Protocol (TFTP) is a simple file transfer protocol that is generally used for automated transfer of configuration or boot files between machines in a local environment.
+In a PXE environment, TFTP is used to download NBP over the network using information from the DHCP server.
+
+|
+IPMI
+------
+|
+Intelligent Platform Management Interface (IPMI) is a standardized computer system interface used by system administrators for out-of-band management of computer systems and monitoring of their operation.
+It is a method to manage systems that may be unresponsive or powered off by using only a network connection to the hardware rather than to an operating system.
+

doc/source/index.rst

@@ -76,6 +76,17 @@ Python API Quick Reference
   dev/drivers
   dev/conductor
 
+Admin Guide
+=======================
+
+Overview
+----------
+
+.. toctree::
+  :maxdepth: 1
+
+  deploy/userguide
+
 Indices and tables
 ==================