Update octavia.rst

doc/source/operations/octavia.rst

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 Octavia
 =======
 
+.. Introduction to Octavia:
+
+Introduction to Octavia
+=======================
+
+Octavia is known as an *operator-scaled* load balancing service, whose primary goal is to
+distribute incoming network traffic, destined for a single VM, across multiple VMs instead;
+thus preventing overloading the VM and improving the overall performance of the VM's outbound
+service.
+
+For more information on Octavia, please refer to the `official documentation <https://docs.openstack.org/octavia/latest/reference/introduction.html>`_.
+
+.. _Deploying Octavia:
+
+Deploying Octavia
+=================
+
+Much like any other Kolla managed service, the method of deploying Octavia is as simple
+as:
+
+#. Enabling ``kolla_enable_octavia: true`` within the chosen environment's ``kolla.yml``.
+
+#. Check ``octavia_net_interface`` is configured in ``${KAYOBE_CONFIG_PATH}/inventory/group_vars/`` (often in ``controllers/network-interfaces.yml``).
+
+   - IF NOT CONFIGURED  
+
+     2.1. Check if a ``bond_interface`` has been configured, still within ``network-interfaces.yml``.  
+
+     2.2. Check whether other network interfaces, such as ``internal_interface``, are configured to use ``{{ bond_interface }}`` and/or ``{{ .._vlan }}``.  
+
+     2.3. If they are, then ``octavia_net_interface: "{{ brbond0_interface }}.{{ octavia_net`` ± ``_vlan }}"``.  
+
+   - IF CONFIGURED   
+
+     2.1. Continue to step 3.
+
+#. Check that the ``{{ .._net_.. }}`` network configured for ``octavia_net_interface`` exists in ``networks.yml``.  
+
+   - IF NOT CONFIGURED  
+
+     3.1. Set ``octavia_net_name: octavia_net``.  
+
+     3.2. Configure the Octavia network IP information, making sure to set ``octavia_net_vlan`` if using a VLAN.  
+
+   - IF CONFIGURED  
+
+     3.1. Continue to step 4.
+
+#. Dependencies if:  
+
+   - USING VLAN  
+
+     4.1. Set ``kolla_enable_neutron_provider_networks: true`` in ``kolla.yml``.  
+
+   - USING AMPHORA  
+
+     4.1. Set ``octavia_loadbalancer_topology: "ACTIVE_STANDBY"`` in ``${KAYOBE_CONFIG_PATH}/kolla/globals.yml``.
+
+#. Run ``kayobe overcloud service configure``.
+
+By default Octavia will deploy an Amphora (a single Ubuntu VM running HAProxy) per load balancing service.
+Consequently, if using Amphora, this default behaviour should be changed to make them highly available so that
+there are two Amphora VMs per service. Achieved by step 4.2 above, this will ensure that if the master Amphora
+VM were to go down, the other would be able to take over the load balancing functions.
+
+Further configuration options and details on installation can be found in the
+`Octavia documentation <https://docs.openstack.org/kolla-ansible/latest/reference/networking/octavia.html>`_.
+
 .. _Amphora image:
 
 Building and rotating amphora images