diff --git a/doc/source/admin/image-building.rst b/doc/source/admin/image-building.rst
index 7adfcac213..6f6d3a4cdd 100644
--- a/doc/source/admin/image-building.rst
+++ b/doc/source/admin/image-building.rst
@@ -74,6 +74,25 @@ There are following distros available for building images:
 - rhel
 - ubuntu
 
+See the :ref:`support matrix <support-matrix-base-images>` for information on
+supported base image distribution versions and supported images on each
+distribution.
+
+The Train ``9.1.0`` release supports both CentOS 7 and 8 base container images.
+The default is to use CentOS 7. CentOS 8 may be used as follows:
+
+.. code-block:: console
+
+   kolla-build --base centos --base-tag 8
+
+Kolla uses the tag to set defaults for the distribution Python version and
+package manager. If you need to use a base image with a different tag, use the
+following options:
+
+.. code-block:: console
+
+   kolla-build --base centos --base-image <base image> --base-tag <base tag> --distro-package-manager dnf --distro-python-version 3.6
+
 .. warning::
 
    Fedora images are deprecated since Newton and will be removed
diff --git a/doc/source/matrix_aarch64.csv b/doc/source/matrix_aarch64.csv
index 28a7c97ade..6bb121e1ab 100644
--- a/doc/source/matrix_aarch64.csv
+++ b/doc/source/matrix_aarch64.csv
@@ -60,6 +60,7 @@ multipathd,C,C,C,C,N,C
 murano,C,C,C,C,N,C
 neutron,C,C,C,C,N,C
 nova,C,C,C,C,N,C
+nova-spicehtml5proxy,N,N,C,C,N,C
 novajoin,C,C,N,C,N,C
 octavia,C,C,N,C,N,C
 opendaylight,N,N,N,N,N,N
diff --git a/doc/source/matrix_x86.csv b/doc/source/matrix_x86.csv
index 2aa5fecb4a..2e25d00fa2 100644
--- a/doc/source/matrix_x86.csv
+++ b/doc/source/matrix_x86.csv
@@ -1,99 +1,102 @@
-Image,CentOS,,Ubuntu,,Debian
-,Binary,Source,Binary,Source,Binary,Source
-almanach (deprecated),N,C,N,C,N,C
-aodh,C,C,C,C,N,C
-barbican,C,T,C,C,N,C
-bifrost,N,T,N,C,N,N
-blazar,N,C,N,C,N,C
-ceilometer,C,C,C,C,N,C
-ceph,C,T,C,T,N,C
-certmonger,C,C,C,C,N,C
-chrony,T,T,T,T,N,T
-cinder,C,T,C,T,N,C
-cloudkitty,C,C,N,C,N,C
-collectd,C,C,C,C,N,C
-congress,C,C,N,C,N,C
-cron,T,T,T,T,N,T
-cyborg,N,C,N,N,N,N
-designate,C,C,C,C,N,C
-dind (deprecated),C,C,C,C,N,C
-dnsmasq,T,T,C,T,N,C
-dragonflow (deprecated),N,C,N,C,N,C
-ec2-api,C,C,N,C,N,C
-elasticsearch,C,C,C,C,N,C
-etcd,C,T,C,T,N,C
-fluentd,T,T,T,T,N,T
-freezer,N,C,N,C,N,C
-glance,T,T,T,T,N,T
-gnocchi,C,C,C,C,N,C
-grafana,C,C,C,C,N,C
-hacluster,C,C,C,C,N,C
-haproxy,T,T,T,T,N,C
-heat,T,T,N,T,N,T
-helm-repository (deprecated),C,C,C,C,N,C
-horizon,T,T,T,T,N,T
-influxdb,C,C,C,C,N,C
-ironic,T,T,C,T,N,C
-ironic-neutron-agent,T,T,N,T,N,C
-ironic-inspector,T,T,C,T,N,C
-iscsid,T,T,T,T,N,C
-kafka,C,C,C,C,N,C
-karbor,N,C,N,C,N,C
-keepalived,T,T,T,T,N,C
-keystone,T,T,T,T,N,T
-kibana,C,C,C,C,N,C
-kolla-toolbox,T,T,T,T,N,T
-kube (deprecated),C,C,C,C,N,C
-kubernetes-entrypoint (deprecated),C,C,C,C,N,C
-kubetoolbox (deprecated),C,C,C,C,N,C
-kuryr,N,T,N,T,N,C
-logstash,C,C,C,C,N,C
-magnum,C,C,C,C,N,C
-manila,C,C,C,C,N,C
-mariadb,T,T,T,T,N,T
-masakari,N,T,N,T,N,C
-memcached,T,T,T,T,N,C
-mistral,C,T,N,C,N,C
-monasca,N,C,N,C,N,N
-mongodb,C,C,C,C,N,N
-multipathd,C,C,C,C,N,C
-murano,C,C,C,C,N,C
-neutron,T,T,T,T,N,T
-nova,T,T,T,T,N,T
-novajoin,C,C,N,C,N,C
-octavia,C,C,N,C,N,C
-opendaylight,C,C,C,C,N,N
-openvswitch,T,T,T,T,N,T
-ovn,C,C,C,C,N,C
-ovsdpdk,N,N,C,C,N,N
-panko,C,C,C,C,N,C
-placement,T,T,T,T,N,T
-prometheus,C,C,C,C,N,C
-ptp,C,C,C,C,N,C
-qdrouterd,C,C,N,N,N,N
-qinling,N,C,N,C,N,C
-rabbitmq,T,T,T,T,N,T
-radvd,C,C,C,C,N,C
-rally,C,C,N,C,N,C
-redis,C,T,C,C,N,C
-rsyslog,C,C,C,C,N,C
-sahara,C,C,C,C,N,C
-searchlight,N,C,N,C,N,C
-senlin,C,C,C,C,N,C
-sensu,C,C,C,C,N,N
-skydive,C,C,C,C,N,C
-solum,N,C,N,C,N,C
-storm,C,C,C,C,N,C
-swift,C,C,C,C,N,C
-tacker,C,T,N,C,N,C
-telegraf,C,C,C,C,N,N
-tempest,C,C,C,C,N,C
-tgtd,C,T,C,T,N,C
-tripleoclient,C,N,N,N,N,N
-trove,C,C,C,C,N,C
-vitrage,C,C,N,C,N,C
-vmtp,N,C,N,C,N,C
-watcher,C,C,C,C,N,C
-zaqar,C,C,N,C,N,C
-zookeeper,C,C,C,C,N,C
-zun,N,T,N,T,N,C
+Image,CentOS 7,,CentOS 8,,Ubuntu,,Debian
+,Binary,Source,Binary,Source,Binary,Source,Binary,Source
+almanach (deprecated),N,C,N,N,N,C,N,C
+aodh,C,C,C,C,C,C,N,C
+barbican,C,T,C,T,C,C,N,C
+bifrost,N,T,N,T,N,C,N,N
+blazar,N,C,N,C,N,C,N,C
+ceilometer,C,C,C,C,C,C,N,C
+ceph,C,T,N,N,C,T,N,C
+certmonger,C,C,C,C,C,C,N,C
+chrony,T,T,T,T,T,T,N,T
+cinder,C,T,C,T,C,T,N,C
+cloudkitty,C,C,C,C,N,C,N,C
+collectd,C,C,C,C,C,C,N,C
+congress,C,C,C,C,N,C,N,C
+cron,T,T,T,T,T,T,N,T
+cyborg,N,C,N,C,N,N,N,N
+cyborg-agent,N,C,N,N,N,N,N,N
+designate,C,C,C,C,C,C,N,C
+dind (deprecated),C,C,N,N,C,C,N,C
+dnsmasq,T,T,T,T,C,T,N,C
+dragonflow (deprecated),N,C,N,N,N,C,N,C
+ec2-api,C,C,C,C,N,C,N,C
+elasticsearch,C,C,N,N,C,C,N,C
+etcd,C,T,C,T,C,T,N,C
+fluentd,T,T,T,T,T,T,N,T
+freezer,N,C,N,C,N,C,N,C
+glance,T,T,T,T,T,T,N,T
+gnocchi,C,C,C,C,C,C,N,C
+grafana,C,C,C,C,C,C,N,C
+hacluster,C,C,C,C,C,C,N,C
+hacluster-pcs,C,C,N,N,C,C,N,C
+haproxy,T,T,T,T,T,T,N,C
+heat,T,T,T,T,N,T,N,T
+helm-repository (deprecated),C,C,N,N,C,C,N,C
+horizon,T,T,T,T,T,T,N,T
+influxdb,C,C,C,C,C,C,N,C
+ironic,T,T,T,T,C,T,N,C
+ironic-neutron-agent,T,T,T,T,N,T,N,C
+ironic-inspector,T,T,T,T,C,T,N,C
+iscsid,T,T,T,T,T,T,N,C
+kafka,C,C,C,C,C,C,N,C
+karbor,N,C,N,C,N,C,N,C
+keepalived,T,T,T,T,T,T,N,C
+keystone,T,T,T,T,T,T,N,T
+kibana,C,C,N,N,C,C,N,C
+kolla-toolbox,T,T,T,T,T,T,N,T
+kube (deprecated),C,C,N,N,C,C,N,C
+kubernetes-entrypoint (deprecated),C,C,N,N,C,C,N,C
+kubetoolbox (deprecated),C,C,N,N,C,C,N,C
+kuryr,N,T,N,T,N,T,N,C
+logstash,C,C,C,C,C,C,N,C
+magnum,C,C,C,C,C,C,N,C
+manila,C,C,C,C,C,C,N,C
+mariadb,T,T,T,T,T,T,N,T
+masakari,N,T,N,T,N,T,N,C
+memcached,T,T,T,T,T,T,N,C
+mistral,C,T,C,T,N,C,N,C
+monasca,N,C,N,C,N,C,N,N
+mongodb,C,C,N,N,C,C,N,N
+multipathd,C,C,C,C,C,C,N,C
+murano,C,C,C,C,C,C,N,C
+neutron,T,T,T,T,T,T,N,T
+nova,T,T,T,T,T,T,N,T
+nova-spicehtml5proxy,T,T,N,N,T,T,N,T
+novajoin,C,C,C,C,N,C,N,C
+octavia,C,C,C,C,N,C,N,C
+opendaylight,C,C,N,N,C,C,N,N
+openvswitch,T,T,T,T,T,T,N,T
+ovn,C,C,C,C,C,C,N,C
+ovsdpdk,N,N,N,N,C,C,N,N
+panko,C,C,C,C,C,C,N,C
+placement,T,T,T,T,T,T,N,T
+prometheus,C,C,C,C,C,C,N,C
+ptp,C,C,C,C,C,C,N,C
+qdrouterd,C,C,C,C,N,N,N,N
+qinling,N,C,N,C,N,C,N,C
+rabbitmq,T,T,T,T,T,T,N,T
+radvd,C,C,C,C,C,C,N,C
+rally,C,C,C,C,N,C,N,C
+redis,C,T,C,T,C,C,N,C
+rsyslog,C,C,C,C,C,C,N,C
+sahara,C,C,C,C,C,C,N,C
+searchlight,N,C,N,C,N,C,N,C
+senlin,C,C,C,C,C,C,N,C
+sensu,C,C,N,N,C,C,N,N
+skydive,C,C,C,C,C,C,N,C
+solum,N,C,N,C,N,C,N,C
+storm,C,C,C,C,C,C,N,C
+swift,C,C,C,C,C,C,N,C
+tacker,C,T,C,T,N,C,N,C
+telegraf,C,C,C,C,C,C,N,N
+tempest,C,C,C,C,C,C,N,C
+tgtd,C,T,C,T,C,T,N,C
+tripleoclient,C,N,C,N,N,N,N,N
+trove,C,C,C,C,C,C,N,C
+vitrage,C,C,C,C,N,C,N,C
+vmtp,N,C,N,C,N,C,N,C
+watcher,C,C,C,C,C,C,N,C
+zaqar,C,C,C,C,N,C,N,C
+zookeeper,C,C,C,C,C,C,N,C
+zun,N,T,N,T,N,T,N,C
diff --git a/doc/source/support_matrix.rst b/doc/source/support_matrix.rst
index 090adc0e0a..955fee0820 100644
--- a/doc/source/support_matrix.rst
+++ b/doc/source/support_matrix.rst
@@ -4,6 +4,35 @@
 Kolla Images Support Matrix
 ===========================
 
+This page describes the supported base container image distributions and
+versions, and the Kolla images supported on each of those.
+
+.. _support-matrix-base-images:
+
+Supported base images
+=====================
+
+The following base container images are supported:
+
+.. note::
+
+   Train is the last release of Kolla to support CentOS 7 as a base container
+   image. The Train ``9.1.0`` release also supports CentOS 8 images, and
+   provides a route for migration.
+
+============= ============ ================
+Distribution  Default base Default base tag
+============= ============ ================
+CentOS 7      centos       7
+CentOS 8      centos       8
+Debian Buster debian       10
+RHEL 8        rhel         8
+Ubuntu Bionic ubuntu       18.04
+============= ============ ================
+
+The remainder of this document outlines which images are supported on which of
+these distributions.
+
 Support clause definitions
 ==========================
 
diff --git a/releasenotes/notes/centos-8-950d979507939643.yaml b/releasenotes/notes/centos-8-950d979507939643.yaml
new file mode 100644
index 0000000000..bd9ae6b12c
--- /dev/null
+++ b/releasenotes/notes/centos-8-950d979507939643.yaml
@@ -0,0 +1,16 @@
+---
+features:
+  - |
+    Adds support for CentOS 8 as a base container image. This is the only major
+    version of CentOS supported from the Ussuri release. The Train release
+    supports both CentOS 7 and 8 images, and provides a route for migration.
+upgrade:
+  - |
+    The following images are supported by CentOS 7 but lack suitable packages
+    in CentOS 8, and are not supported for CentOS 8: ``cyborg-agent``,
+    ``hacluster-pcs``, ``nova-spicehtml5proxy``.
+  - |
+    The following images are supported by CentOS 7 but are not supported for
+    CentOS 8 as they have been dropped in Ussuri: ``almanach-*``, ``ceph-*``,
+    ``dind``, ``dragonflow-*``, ``helm-repository``, ``kube*``, ``mongodb``,
+    ``opendaylight``, ``sensu```.