diff --git a/ansible/group_vars/all/kolla b/ansible/group_vars/all/kolla
index 07a9ca939..0b89f629f 100644
--- a/ansible/group_vars/all/kolla
+++ b/ansible/group_vars/all/kolla
@@ -153,6 +153,50 @@ kolla_build_blocks: {}
 # remove. The value should be a list.
 kolla_build_customizations: {}
 
+###############################################################################
+# Kolla-ansible inventory configuration.
+
+# Full custom seed inventory contents.
+kolla_seed_inventory_custom:
+
+# Custom overcloud inventory containing a mapping from top level groups to
+# hosts.
+kolla_overcloud_inventory_custom_top_level:
+
+# Custom overcloud inventory containing a mapping from components to top level
+# groups.
+kolla_overcloud_inventory_custom_components:
+
+# Custom overcloud inventory containing a mapping from services to components.
+kolla_overcloud_inventory_custom_services:
+
+# Full custom overcloud inventory contents. By default this will be the
+# concatenation of the top level, component, and service inventories.
+kolla_overcloud_inventory_custom:
+
+# Dict mapping from kolla-ansible groups to kayobe groups and variables. Each
+# item is a dict with the following items:
+# * groups: A list of kayobe ansible groups to map to this kolla-ansible group.
+# * vars: A dict mapping variable names to values for hosts in this
+#         kolla-ansible group.
+kolla_overcloud_inventory_top_level_group_map:
+  control:
+    groups:
+      - controllers
+  network:
+    groups:
+      - network
+
+# List of names of top level kolla-ansible groups. Any of these groups which
+# have no hosts mapped to them will be provided with an empty group definition.
+kolla_overcloud_inventory_kolla_top_level_groups:
+  - "control"
+  - "network"
+  - "compute"
+  - "monitoring"
+  - "storage"
+  - "deployment"
+
 ###############################################################################
 # Kolla-ansible configuration.
 
diff --git a/ansible/roles/kolla-ansible/defaults/main.yml b/ansible/roles/kolla-ansible/defaults/main.yml
index da0dace26..8db76a077 100644
--- a/ansible/roles/kolla-ansible/defaults/main.yml
+++ b/ansible/roles/kolla-ansible/defaults/main.yml
@@ -24,6 +24,41 @@ kolla_config_path:
 # Directory where Kolla custom configuration files will be installed.
 kolla_node_custom_config_path:
 
+###############################################################################
+# Kolla-ansible inventory configuration.
+
+# Full custom seed inventory contents.
+kolla_seed_inventory_custom:
+
+# Custom overcloud inventory containing a mapping from top level groups to
+# hosts.
+kolla_overcloud_inventory_custom_top_level:
+
+# Custom overcloud inventory containing a mapping from components to top level
+# groups.
+kolla_overcloud_inventory_custom_components:
+
+# Custom overcloud inventory containing a mapping from services to components.
+kolla_overcloud_inventory_custom_services:
+
+# Full custom overcloud inventory contents. By default this will be the
+# concatenation of the top level, component, and service inventories.
+kolla_overcloud_inventory_custom:
+
+# Dict mapping from kolla-ansible groups to kayobe groups and variables. Each
+# item is a dict with the following items:
+# * groups: A list of kayobe ansible groups to map to this kolla-ansible group.
+# * vars: A dict mapping variable names to values for hosts in this
+#         kolla-ansible group.
+kolla_overcloud_inventory_top_level_group_map: {}
+
+# List of names of top level kolla-ansible groups. Any of these groups which
+# have no hosts mapped to them will be provided with an empty group definition.
+kolla_overcloud_inventory_kolla_top_level_groups: []
+
+###############################################################################
+# Kolla-ansible global configuration options.
+
 # Valid options are [ centos, fedora, oraclelinux, ubuntu ]
 kolla_base_distro:
 
diff --git a/ansible/roles/kolla-ansible/tasks/config.yml b/ansible/roles/kolla-ansible/tasks/config.yml
index 97f7abcf6..b7d80703d 100644
--- a/ansible/roles/kolla-ansible/tasks/config.yml
+++ b/ansible/roles/kolla-ansible/tasks/config.yml
@@ -12,15 +12,26 @@
     - "{{ kolla_config_path }}/inventory"
     - "{{ kolla_node_custom_config_path }}"
 
-- name: Ensure the Kolla configuration files exist
+- name: Ensure the Kolla global configuration file exists
   template:
-    src: "{{ item.src }}"
-    dest: "{{ kolla_config_path }}/{{ item.dest }}"
+    src: "globals.yml.j2"
+    dest: "{{ kolla_config_path }}/globals.yml"
+    mode: 0640
+
+# NOTE: We're not looping over the two inventory files to avoid having the file
+# content displayed in the ansible-playbook output.
+
+- name: Ensure the Kolla seed inventory file exists
+  copy:
+    content: "{{ kolla_seed_inventory }}"
+    dest: "{{ kolla_config_path }}/inventory/seed"
+    mode: 0640
+
+- name: Ensure the Kolla overcloud inventory file exists
+  copy:
+    content: "{{ kolla_overcloud_inventory }}"
+    dest: "{{ kolla_config_path }}/inventory/overcloud"
     mode: 0640
-  with_items:
-    - { src: seed.j2, dest: inventory/seed }
-    - { src: overcloud.j2, dest: inventory/overcloud }
-    - { src: globals.yml.j2, dest: globals.yml }
 
 - name: Ensure the Kolla passwords file exists
   kolla_passwords:
diff --git a/ansible/roles/kolla-ansible/templates/overcloud-components.j2 b/ansible/roles/kolla-ansible/templates/overcloud-components.j2
new file mode 100644
index 000000000..de3c274ea
--- /dev/null
+++ b/ansible/roles/kolla-ansible/templates/overcloud-components.j2
@@ -0,0 +1,201 @@
+# This inventory section provides a mapping of the components to top level
+# groups.
+#
+# Top level groups define the roles of hosts, e.g. controller or compute.
+# Components define groups of services, e.g. nova or ironic.
+# Services define single containers, e.g. nova-compute or ironic-api.
+
+[baremetal:children]
+control
+network
+compute
+storage
+monitoring
+
+# You can explicitly specify which hosts run each project by updating the
+# groups in the sections below. Common services are grouped together.
+[chrony-server:children]
+control
+
+[chrony:children]
+control
+network
+compute
+storage
+monitoring
+
+[collectd:children]
+compute
+
+[grafana:children]
+monitoring
+
+[etcd:children]
+control
+
+[influxdb:children]
+monitoring
+
+[karbor:children]
+control
+
+[kibana:children]
+control
+
+[telegraf:children]
+compute
+control
+monitoring
+network
+storage
+
+[elasticsearch:children]
+control
+
+[haproxy:children]
+network
+
+[hyperv]
+#hyperv_host
+
+[hyperv:vars]
+#ansible_user=user
+#ansible_password=password
+#ansible_port=5986
+#ansible_connection=winrm
+#ansible_winrm_server_cert_validation=ignore
+
+[mariadb:children]
+control
+
+[rabbitmq:children]
+control
+
+[outward-rabbitmq:children]
+control
+
+[mongodb:children]
+control
+
+[keystone:children]
+control
+
+[glance:children]
+control
+
+[nova:children]
+control
+
+[neutron:children]
+network
+
+[openvswitch:children]
+network
+compute
+manila-share
+
+[cinder:children]
+control
+
+[cloudkitty:children]
+control
+
+[freezer:children]
+control
+
+[memcached:children]
+control
+
+[horizon:children]
+control
+
+[swift:children]
+control
+
+[barbican:children]
+control
+
+[heat:children]
+control
+
+[murano:children]
+control
+
+[solum:children]
+control
+
+[ironic:children]
+control
+
+[ceph:children]
+control
+
+[magnum:children]
+control
+
+[sahara:children]
+control
+
+[mistral:children]
+control
+
+[manila:children]
+control
+
+[ceilometer:children]
+control
+
+[aodh:children]
+control
+
+[congress:children]
+control
+
+[panko:children]
+control
+
+[gnocchi:children]
+control
+
+[tacker:children]
+control
+
+[trove:children]
+control
+
+# Tempest
+[tempest:children]
+control
+
+[senlin:children]
+control
+
+[vmtp:children]
+control
+
+[watcher:children]
+control
+
+[rally:children]
+control
+
+[searchlight:children]
+control
+
+[octavia:children]
+control
+
+[designate:children]
+control
+
+[placement:children]
+control
+
+[bifrost:children]
+deployment
+
+[zun:children]
+control
+
+[skydive:children]
+monitoring
diff --git a/ansible/roles/kolla-ansible/templates/overcloud.j2 b/ansible/roles/kolla-ansible/templates/overcloud-services.j2
similarity index 56%
rename from ansible/roles/kolla-ansible/templates/overcloud.j2
rename to ansible/roles/kolla-ansible/templates/overcloud-services.j2
index a7dcbf804..9e12c936c 100644
--- a/ansible/roles/kolla-ansible/templates/overcloud.j2
+++ b/ansible/roles/kolla-ansible/templates/overcloud-services.j2
@@ -1,243 +1,8 @@
-# {{ ansible_managed }}
-
-# Overcloud inventory for Kolla. Adapted from multinode inventory in Kolla
-# repository.
-
-[controllers]
-# These hostnames must be resolvable from your deployment host
-{% for controller in groups['controllers'] %}
-{% set controller_hv=hostvars[controller] %}
-{{ controller }}{% if "ansible_host" in controller_hv %}    ansible_host={{ controller_hv["ansible_host"] }}{% endif %}
-
-{% endfor %}
-
-[controllers:vars]
-ansible_user=kolla
-ansible_become=true
-
-# These initial groups are the only groups required to be modified. The
-# additional groups are for more control of the environment.
-[control:children]
-controllers
-
-# The network nodes are where your l3-agent and loadbalancers will run
-# This can be the same as a host in the control group
-[network:children]
-controllers
-
-[compute:children]
-
-[monitoring]
-# These hostnames must be resolvable from your deployment host
-{% for monitoring_host in groups['monitoring'] %}
-{% set monitoring_hv=hostvars[monitoring_host] %}
-{{ monitoring_host }}{% if "ansible_host" in monitoring_hv %}    ansible_host={{ monitoring_hv["ansible_host"] }}{% endif %}
-
-{% endfor %}
-
-[monitoring:vars]
-ansible_user=kolla
-ansible_become=true
-
-[storage:children]
-controllers
-
-[deployment]
-
-[baremetal:children]
-control
-network
-compute
-storage
-monitoring
-
-# You can explicitly specify which hosts run each project by updating the
-# groups in the sections below. Common services are grouped together.
-[chrony-server:children]
-control
-
-[chrony:children]
-control
-network
-compute
-storage
-monitoring
-
-[collectd:children]
-compute
-
-[grafana:children]
-monitoring
-
-[etcd:children]
-control
-
-[influxdb:children]
-monitoring
-
-[karbor:children]
-control
-
-[kibana:children]
-control
-
-[telegraf:children]
-compute
-control
-monitoring
-network
-storage
-
-[elasticsearch:children]
-control
-
-[haproxy:children]
-network
-
-[hyperv]
-#hyperv_host
-
-[hyperv:vars]
-#ansible_user=user
-#ansible_password=password
-#ansible_port=5986
-#ansible_connection=winrm
-#ansible_winrm_server_cert_validation=ignore
-
-[mariadb:children]
-control
-
-[rabbitmq:children]
-control
-
-[outward-rabbitmq:children]
-control
-
-[mongodb:children]
-control
-
-[keystone:children]
-control
-
-[glance:children]
-control
-
-[nova:children]
-control
-
-[neutron:children]
-network
-
-[openvswitch:children]
-network
-compute
-manila-share
-
-[cinder:children]
-control
-
-[cloudkitty:children]
-control
-
-[freezer:children]
-control
-
-[memcached:children]
-control
-
-[horizon:children]
-control
-
-[swift:children]
-control
-
-[barbican:children]
-control
-
-[heat:children]
-control
-
-[murano:children]
-control
-
-[solum:children]
-control
-
-[ironic:children]
-control
-
-[ceph:children]
-control
-
-[magnum:children]
-control
-
-[sahara:children]
-control
-
-[mistral:children]
-control
-
-[manila:children]
-control
-
-[ceilometer:children]
-control
-
-[aodh:children]
-control
-
-[congress:children]
-control
-
-[panko:children]
-control
-
-[gnocchi:children]
-control
-
-[tacker:children]
-control
-
-[trove:children]
-control
-
-# Tempest
-[tempest:children]
-control
-
-[senlin:children]
-control
-
-[vmtp:children]
-control
-
-[watcher:children]
-control
-
-[rally:children]
-control
-
-[searchlight:children]
-control
-
-[octavia:children]
-control
-
-[designate:children]
-control
-
-[placement:children]
-control
-
-[bifrost:children]
-deployment
-
-[zun:children]
-control
-
-[skydive:children]
-monitoring
+# This inventory section provides a mapping of services to components.
+#
+# Top level groups define the roles of hosts, e.g. controller or compute.
+# Components define groups of services, e.g. nova or ironic.
+# Services define single containers, e.g. nova-compute or ironic-api.
 
 # Additional control implemented here. These groups allow you to control which
 # services run on which hosts at a per-service level.
@@ -413,8 +178,16 @@ ironic
 [ironic-conductor:children]
 ironic
 
-[ironic-inspector:children]
-ironic
+#[ironic-inspector:children]
+#ironic
+
+[ironic-inspector]
+# FIXME: Ideally we wouldn't reference controllers in here directly, but only
+# one inspector service should exist, and groups can't be indexed in an
+# inventory (e.g. ironic[0]).
+{% if groups['controllers'] | length > 0 %}
+{{ groups['controllers'][0] }}
+{% endif %}
 
 [ironic-pxe:children]
 ironic
diff --git a/ansible/roles/kolla-ansible/templates/overcloud-top-level.j2 b/ansible/roles/kolla-ansible/templates/overcloud-top-level.j2
new file mode 100644
index 000000000..99e55f2ae
--- /dev/null
+++ b/ansible/roles/kolla-ansible/templates/overcloud-top-level.j2
@@ -0,0 +1,63 @@
+# This inventory section provides a mapping of the top level groups to hosts.
+#
+# Top level groups define the roles of hosts, e.g. controller or compute.
+# Components define groups of services, e.g. nova or ironic.
+# Services define single containers, e.g. nova-compute or ironic-api.
+
+{% set top_level_groups = kolla_overcloud_inventory_top_level_group_map.values() |
+                          selectattr('groups', 'defined') |
+                          map(attribute='groups') |
+                          sum(start=[]) |
+                          unique |
+                          list %}
+
+{% for group in top_level_groups %}
+# Top level {{ group }} group.
+[{{ group }}]
+# These hostnames must be resolvable from your deployment host
+{% for host in groups[group] %}
+{% set host_hv=hostvars[host] %}
+{{ host }}{% if "ansible_host" in host_hv %}    ansible_host={{ host_hv["ansible_host"] }}{% endif %}
+
+{% endfor %}
+
+{% endfor %}
+[overcloud:children]
+{% for group in top_level_groups %}
+{{ group }}
+{% endfor %}
+
+[overcloud:vars]
+ansible_user=kolla
+ansible_become=true
+
+{% for kolla_group, kolla_group_config in kolla_overcloud_inventory_top_level_group_map.items() %}
+{% if 'groups' in kolla_group_config %}
+{% set renamed_groups = kolla_group_config.groups | difference([kolla_group]) | list %}
+{% if renamed_groups | length > 0 %}
+# Mapping from kolla-ansible group {{ kolla_group }} to top level kayobe
+# groups.
+[{{ kolla_group }}:children]
+{% for group in kolla_group_config.groups %}
+{{ group }}
+{% endfor %}
+
+{% endif %}
+{% endif %}
+{% if 'vars' in kolla_group_config %}
+# Mapping from kolla-ansible group {{ kolla_group }} to top level kayobe
+# variables.
+[{{ kolla_group }}:vars]
+{% for var_name, var_value in kayobe_group_config.vars.items() %}
+{{ var_name }}={{ var_value }}
+{% endfor %}
+
+{% endif %}
+{% endfor %}
+{% for group in kolla_overcloud_inventory_kolla_top_level_groups %}
+{% if group not in kolla_overcloud_inventory_top_level_group_map %}
+# Empty group definition for {{ group }}.
+[{{ group }}]
+
+{% endif %}
+{% endfor %}
diff --git a/ansible/roles/kolla-ansible/templates/seed.j2 b/ansible/roles/kolla-ansible/templates/seed.j2
index f8798a068..6fa1609a8 100644
--- a/ansible/roles/kolla-ansible/templates/seed.j2
+++ b/ansible/roles/kolla-ansible/templates/seed.j2
@@ -1,5 +1,3 @@
-# {{ ansible_managed }}
-
 # Simple inventory for bootstrapping Kolla seed node.
 [seed]
 {% for seed in groups['seed'] %}
diff --git a/ansible/roles/kolla-ansible/vars/main.yml b/ansible/roles/kolla-ansible/vars/main.yml
index 5b165cdc6..d6717225d 100644
--- a/ansible/roles/kolla-ansible/vars/main.yml
+++ b/ansible/roles/kolla-ansible/vars/main.yml
@@ -8,6 +8,58 @@ kolla_ansible_module: "{% if kolla_ansible_is_standalone | bool %}kolla-ansible{
 # Path to Kolla Ansible installation directory.
 kolla_ansible_install_dir: "{{ kolla_venv }}/share/{{ kolla_ansible_module }}"
 
+###############################################################################
+# Inventory configuration.
+
+# Full default seed inventory contents.
+kolla_seed_inventory_default: |
+  # This file is managed by Ansible. Do not edit.
+
+  {{ lookup('template', "seed.j2") }}
+
+# Full seed inventory contents.
+kolla_seed_inventory: "{{ kolla_seed_inventory_custom or kolla_seed_inventory_default }}"
+
+# Default overcloud inventory containing a mapping from top level groups to
+# hosts.
+kolla_overcloud_inventory_default_top_level: "{{ lookup('template', 'overcloud-top-level.j2') }}"
+
+# Overcloud inventory containing a mapping from top level groups to hosts.
+kolla_overcloud_inventory_top_level: "{{ kolla_overcloud_inventory_custom_top_level or kolla_overcloud_inventory_default_top_level }}"
+
+# Default overcloud inventory containing a mapping from components to top level
+# groups.
+kolla_overcloud_inventory_default_components: "{{ lookup('template', 'overcloud-components.j2') }}"
+
+# Overcloud inventory containing a mapping from components to top level groups.
+kolla_overcloud_inventory_components: "{{ kolla_overcloud_inventory_custom_components or kolla_overcloud_inventory_default_components }}"
+
+# Default overcloud inventory containing a mapping from services to components.
+kolla_overcloud_inventory_default_services: "{{ lookup('template', 'overcloud-services.j2') }}"
+
+# Overcloud inventory containing a mapping from services to components.
+kolla_overcloud_inventory_services: "{{ kolla_overcloud_inventory_custom_services or kolla_overcloud_inventory_default_services }}"
+
+# Full default overcloud inventory contents. By default this will be the
+# concatenation of the top level, component, and service inventories.
+kolla_overcloud_inventory_default: |
+  # This file is managed by Ansible. Do not edit.
+
+  # Overcloud inventory file for kolla-ansible.
+
+  {{ kolla_overcloud_inventory_top_level }}
+
+  {{ kolla_overcloud_inventory_components }}
+
+  {{ kolla_overcloud_inventory_services }}
+
+# Full overcloud inventory contents. By default this will be the concatenation
+# of the top level, component, and service inventories.
+kolla_overcloud_inventory: "{{ kolla_overcloud_inventory_custom or kolla_overcloud_inventory_default }}"
+
+###############################################################################
+# Feature configuration.
+
 # List of features supported by Kolla as enable_* flags.
 kolla_feature_flags:
   - aodh
@@ -48,3 +100,4 @@ kolla_feature_flags:
   - telegraf
   - tempest
   - watcher
+
diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index 7db44316d..d1c2bd06e 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -90,7 +90,12 @@ Seed
     should exist in the ``seed`` group.
 
 Cloud hosts and bare metal compute hosts are not required to exist in the
-inventory.
+inventory if discovery of the control plane hardware is planned, although
+entries for groups may still be required.
+
+Use of advanced control planes with multiple server roles and customised
+service placement across those servers is covered in
+:ref:`control-plane-service-placement`.
 
 Site Localisation and Customisation
 -----------------------------------
diff --git a/doc/source/control-plane-service-placement.rst b/doc/source/control-plane-service-placement.rst
new file mode 100644
index 000000000..5170aeaa5
--- /dev/null
+++ b/doc/source/control-plane-service-placement.rst
@@ -0,0 +1,219 @@
+.. _control-plane-service-placement:
+
+===============================
+Control Plane Service Placement
+===============================
+
+.. note::
+
+   This is an advanced topic and should only be attempted when familiar with
+   kayobe and OpenStack.
+
+The default configuration in kayobe places all control plane services on a
+single set of servers described as 'controllers'.  In some cases it may be
+necessary to introduce more than one server role into the control plane, and
+control which services are placed onto the different server roles.
+
+Configuration
+=============
+
+Overcloud Inventory Discovery
+-----------------------------
+
+If using a seed host to enable discovery of the control plane services, it is
+necessary to configure how the discovered hosts map into kayobe groups. This
+is done using the ``overcloud_group_hosts_map`` variable, which maps names of
+kayobe groups to a list of the hosts to be added to that group.
+
+This variable will be used during the command ``kayobe overcloud inventory
+discover``.  An inventory file will be generated in
+``${KAYOBE_CONFIG_PATH}/inventory/overcloud`` with discovered hosts added to
+appropriate kayobe groups based on ``overcloud_group_hosts_map``.
+
+Kolla-ansible Inventory Mapping
+-------------------------------
+
+Once hosts have been discovered and enrolled into the kayobe inventory, they
+must be added to the kolla-ansible inventory.  This is done by mapping from top
+level kayobe groups to top level kolla-ansible groups using the
+``kolla_overcloud_inventory_top_level_group_map`` variable.  This variable maps
+from kolla-ansible groups to lists of kayobe groups, and variables to define
+for those groups in the kolla-ansible inventory.
+
+Variables For Custom Server Roles
+---------------------------------
+
+Certain variables must be defined for hosts in the ``overcloud`` group.  For
+hosts in the ``controllers`` group, many variables are mapped to other
+variables with a ``controller_`` prefix in files under
+``ansible/group_vars/controllers/``. This is done in order that they may be set
+in a global extra variables file, typically ``controllers.yml``, with defaults
+set in ``ansible/group_vars/all/controllers``.  A similar scheme is used for
+hosts in the ``monitoring`` group.
+
+.. table:: Overcloud host variables
+
+   ====================== =====================================================
+   Variable               Purpose
+   ====================== =====================================================
+   ``ansible_user``       Username with which to access the host via SSH.
+   ``bootstrap_user``     Username with which to access the host before
+                          ``ansible_user`` is configured.
+   ``lvm_groups``         List of LVM volume groups to configure.  See
+                          `mrlesmithjr.manage-lvm role
+                          <https://galaxy.ansible.com/mrlesmithjr/manage-lvm/>`_
+                          for format.
+   ``network_interfaces`` List of names of networks to which the host is
+                          connected.
+   ====================== =====================================================
+
+If configuring BIOS and RAID via ``kayobe overcloud bios raid configure``, the
+following variables should also be defined:
+
+.. table:: Overcloud BIOS & RAID host variables
+
+   ====================== =====================================================
+   Variable               Purpose
+   ====================== =====================================================
+   ``bios_config``        Dict mapping BIOS configuration options to their
+                          required values. See `stackhpc.drac role
+                          <https://galaxy.ansible.com/stackhpc/drac/>`_ for
+                          format.
+   ``raid_config``        List of RAID virtual disks to configure. See
+                          `stackhpc.drac role
+                          <https://galaxy.ansible.com/stackhpc/drac/>`_ for
+                          format.
+   ====================== =====================================================
+
+These variables can be defined in inventory host or group variables files,
+under ``${KAYOBE_CONFIG_PATH}/inventory/host_vars/<host>`` or
+``${KAYOBE_CONFIG_PATH}/inventory/group_vars/<group>`` respectively.
+
+Custom Kolla-ansible Inventories
+--------------------------------
+
+As an advanced option, it is possible to fully customise the content of the
+kolla-ansible inventory, at various levels.  To facilitate this, kayobe breaks
+the kolla-ansible inventory into three separate sections.
+
+**Top level** groups define the roles of hosts, e.g. ``controller`` or ``compute``,
+and it is to these groups that hosts are mapped directly.
+
+**Components** define groups of services, e.g. ``nova`` or ``ironic``, which
+are mapped to top level groups.
+
+**Services** define single containers, e.g. ``nova-compute`` or ``ironic-api``,
+which are mapped to components.
+
+The default top level inventory is generated from
+``kolla_overcloud_inventory_top_level_group_map``.
+Kayobe's component- and service-level inventory for
+kolla-ansible is static, and taken from the kolla-ansible example ``multinode``
+inventory.  The complete inventory is generated by concatenating these
+inventories.
+
+Each level may be separately overridden by setting the following variables:
+
+.. table:: Custom kolla-ansible inventory variables
+
+   =============================================== =================================
+   Variable                                        Purpose
+   =============================================== =================================
+   ``kolla_overcloud_inventory_custom_top_level``  Overcloud inventory containing a
+                                                   mapping from top level groups
+                                                   to hosts.
+   ``kolla_overcloud_inventory_custom_components`` Overcloud inventory
+                                                   containing a mapping from
+                                                   components to top level
+                                                   groups.
+   ``kolla_overcloud_inventory_custom_services``   Overcloud inventory
+                                                   containing a mapping from
+                                                   services to components.
+   ``kolla_overcloud_inventory_custom``            Full overcloud inventory
+                                                   contents.
+   =============================================== =================================
+
+Examples
+========
+
+Example 1: Adding Network Hosts
+-------------------------------
+
+This example walks through the configuration that could be applied to enable
+the use of separate hosts for neutron network services and load balancing.
+The control plane consists of three controllers, ``controller-[0-2]``, and two
+network hosts, ``network-[0-1]``. All file paths are relative to
+``${KAYOBE_CONFIG_PATH}``.
+
+First, we must map the hosts to kayobe groups.
+
+.. code-block:: yaml
+   :caption: ``overcloud.yml``
+
+   overcloud_group_hosts_map:
+     controllers:
+       - controller-0
+       - controller-1
+       - controller-2
+     network:
+       - network-0
+       - network-1
+
+Next, we must map these groups to kolla-ansible groups.
+
+.. code-block:: yaml
+   :caption: ``kolla.yml``
+
+   kolla_overcloud_inventory_top_level_group_map:
+     control:
+       groups:
+         - controllers
+     network:
+       groups:
+         - network
+
+Finally, we create a group variables file for hosts in the network group,
+providing the necessary variables for a control plane host.
+
+.. code-block:: yaml
+   :caption: ``inventory/group_vars/network``
+
+   ansible_user: "{{ kayobe_ansible_user }}"
+   bootstrap_user: "{{ controller_bootstrap_user }}"
+   lvm_groups: "{{ controller_lvm_groups }}"
+   network_interfaces: "{{ controller_network_host_network_interfaces }}"
+
+Here we are using the controller-specific values for some of these variables,
+but they could equally be different.
+
+Example 2: Overriding the Kolla-ansible Inventory
+-------------------------------------------------
+
+This example shows how to override one or more sections of the kolla-ansible
+inventory.  All file paths are relative to ``${KAYOBE_CONFIG_PATH}``.
+
+First, create a file containing the customised inventory section. We'll use the
+**components** section in this example.
+
+.. code-block:: console
+   :caption: ``kolla/inventory/overcloud-components.j2``
+
+   [nova]
+   control
+
+   [ironic]
+   {% if kolla_enable_ironic | bool %}
+   control
+   {% endif %}
+
+   ...
+
+Next, we must configure kayobe to use this inventory template.
+
+.. code-block:: yaml
+   :caption: ``kolla.yml``
+
+   kolla_overcloud_inventory_custom_components: "{{ lookup('template', kayobe_config_path ~ '/kolla/inventory/overcloud-components.j2') }}"
+
+Here we use the ``template`` lookup plugin to render the Jinja2-formatted
+inventory template.
diff --git a/doc/source/index.rst b/doc/source/index.rst
index e4733ca05..1f3d60f93 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -28,6 +28,14 @@ Documentation
    upgrading
    administration
 
+Advanced Documentation
+----------------------
+
+.. toctree::
+   :maxdepth: 2
+
+   control-plane-service-placement
+
 Developer Documentation
 -----------------------
 
diff --git a/etc/kayobe/kolla.yml b/etc/kayobe/kolla.yml
index c154d2276..21be07500 100644
--- a/etc/kayobe/kolla.yml
+++ b/etc/kayobe/kolla.yml
@@ -63,6 +63,38 @@
 # remove. The value should be a list.
 #kolla_build_customizations:
 
+###############################################################################
+# Kolla-ansible inventory configuration.
+
+# Full custom seed inventory contents.
+#kolla_seed_inventory_custom:
+
+# Custom overcloud inventory containing a mapping from top level groups to
+# hosts.
+#kolla_overcloud_inventory_custom_top_level:
+
+# Custom overcloud inventory containing a mapping from components to top level
+# groups.
+#kolla_overcloud_inventory_custom_components:
+
+# Custom overcloud inventory containing a mapping from services to components.
+#kolla_overcloud_inventory_custom_services:
+
+# Full custom overcloud inventory contents. By default this will be the
+# concatenation of the top level, component, and service inventories.
+#kolla_overcloud_inventory_custom:
+
+# Dict mapping from kolla-ansible groups to kayobe groups and variables. Each
+# item is a dict with the following items:
+# * groups: A list of kayobe ansible groups to map to this kolla-ansible group.
+# * vars: A dict mapping variable names to values for hosts in this
+#         kolla-ansible group.
+#kolla_overcloud_inventory_top_level_group_map:
+
+# List of names of top level kolla-ansible groups. Any of these groups which
+# have no hosts mapped to them will be provided with an empty group definition.
+#kolla_overcloud_inventory_kolla_top_level_groups:
+
 ###############################################################################
 # Kolla-ansible configuration.