diff --git a/ansible/group_vars/all/bifrost b/ansible/group_vars/all/bifrost
index ce2fa2df2..c9c529e62 100644
--- a/ansible/group_vars/all/bifrost
+++ b/ansible/group_vars/all/bifrost
@@ -15,10 +15,10 @@ kolla_bifrost_source_version: "{{ openstack_branch }}"
 # Diskimage-builder configuration.
 
 # DIB base OS element.
-kolla_bifrost_dib_os_element: "centos7"
+kolla_bifrost_dib_os_element: "centos"
 
 # DIB image OS release.
-kolla_bifrost_dib_os_release: "GenericCloud"
+kolla_bifrost_dib_os_release: "8"
 
 # List of default DIB elements.
 kolla_bifrost_dib_elements_default:
@@ -38,6 +38,10 @@ kolla_bifrost_dib_init_element: "cloud-init-datasources"
 # DIB default environment variables.
 kolla_bifrost_dib_env_vars_default:
   DIB_CLOUD_INIT_DATASOURCES: "ConfigDrive"
+  # FIXME(mgoddard): DIB fails when cleaning up old kernels if the host running
+  # DIB is not running the latest available kernel. Skip this cleanup as a
+  # workaround. https://bugs.launchpad.net/diskimage-builder/+bug/1866847
+  DIB_DISABLE_KERNEL_CLEANUP: 1
 
 # DIB additional environment variables.
 kolla_bifrost_dib_env_vars_extra: {}
diff --git a/ansible/group_vars/all/overcloud b/ansible/group_vars/all/overcloud
index e01e1ed49..7383833b7 100644
--- a/ansible/group_vars/all/overcloud
+++ b/ansible/group_vars/all/overcloud
@@ -8,7 +8,7 @@ overcloud_group_default: controllers
 
 # List of names of Ansible groups for overcloud hosts.
 overcloud_groups: >
-  {{ (list(overcloud_group_hosts_map) +
+  {{ (overcloud_group_hosts_map | list +
       [overcloud_group_default]) | reject('equalto', 'ignore') | unique | sort | list }}
 
 # Dict mapping overcloud Ansible group names to lists of hosts in the group.
diff --git a/ansible/group_vars/all/seed-vm b/ansible/group_vars/all/seed-vm
index 828ca6dd2..2b113ebfc 100644
--- a/ansible/group_vars/all/seed-vm
+++ b/ansible/group_vars/all/seed-vm
@@ -41,7 +41,7 @@ seed_vm_root_capacity: 50G
 seed_vm_root_format: qcow2
 
 # Base image for the seed VM root volume.
-seed_vm_root_image: "https://cloud.centos.org/centos/7/images/CentOS-7-x86_64-GenericCloud.qcow2"
+seed_vm_root_image: "https://cloud.centos.org/centos/8/x86_64/images/CentOS-8-GenericCloud-8.1.1911-20200113.3.x86_64.qcow2"
 
 # Capacity of the seed VM data volume.
 seed_vm_data_capacity: 100G
diff --git a/ansible/network.yml b/ansible/network.yml
index 2db2ffe10..1056d51c3 100644
--- a/ansible/network.yml
+++ b/ansible/network.yml
@@ -96,7 +96,7 @@
         # interfaces with an explicit MTU set will be taken account of. If no
         # interface has an explicit MTU set, then the corresponding veth will
         # not either.
-        mtu_list: "{{ [veth_bridge_mtu_map.get(interface), item | net_mtu] | reject('none') | list }}"
+        mtu_list: "{{ [veth_bridge_mtu_map.get(interface), item | net_mtu] | select | map('int') | list }}"
         mtu: "{{ mtu_list | max if mtu_list | length > 0 else None }}"
 
     - name: Update a fact containing veth interfaces
diff --git a/ansible/roles/snat/tasks/main.yml b/ansible/roles/snat/tasks/main.yml
index 1ddb3aff6..ef9849ac4 100644
--- a/ansible/roles/snat/tasks/main.yml
+++ b/ansible/roles/snat/tasks/main.yml
@@ -1,4 +1,9 @@
 ---
+- name: Ensure iptables is installed
+  package:
+    name: iptables
+  become: true
+
 # iptables -t nat -A POSTROUTING -o {{ interface }} -j SNAT --to-source {{ source_ip }}
 - name: Ensure SNAT iptables rules exist
   iptables:
diff --git a/doc/source/configuration/bifrost.rst b/doc/source/configuration/bifrost.rst
index a8673a716..dbb73fbdb 100644
--- a/doc/source/configuration/bifrost.rst
+++ b/doc/source/configuration/bifrost.rst
@@ -52,9 +52,9 @@ configuration drive built by Bifrost, rather than the Bifrost default of
 :diskimage-builder-doc:`simple-init <elements/simple-init/README>`.
 
 ``kolla_bifrost_dib_os_element``
-    DIB base OS element. Default is ``centos7``.
+    DIB base OS element. Default is ``centos``.
 ``kolla_bifrost_dib_os_release``
-    DIB image OS release. Default is ``GenericCloud``.
+    DIB image OS release. Default is ``8``.
 ``kolla_bifrost_dib_elements_default``
     *Added in the Train release. Use kolla_bifrost_dib_elements in earlier
     releases.*
@@ -78,7 +78,8 @@ configuration drive built by Bifrost, rather than the Bifrost default of
     releases.*
 
     DIB default environment variables. Default is
-    ``{"DIB_CLOUD_INIT_DATASOURCES": "ConfigDrive"}``.
+    ``{"DIB_CLOUD_INIT_DATASOURCES": "ConfigDrive",
+    "DIB_DISABLE_KERNEL_CLEANUP": 1}``.
 ``kolla_bifrost_dib_env_vars_extra``
     *Added in the Train release. Use kolla_bifrost_dib_env_vars in earlier
     releases.*
diff --git a/etc/kayobe/bifrost.yml b/etc/kayobe/bifrost.yml
index 60254d2d2..61710b5e4 100644
--- a/etc/kayobe/bifrost.yml
+++ b/etc/kayobe/bifrost.yml
@@ -14,34 +14,38 @@
 ###############################################################################
 # Diskimage-builder configuration.
 
-# DIB base OS element.
+# DIB base OS element. Default is "centos".
 #kolla_bifrost_dib_os_element:
 
-# DIB image OS release.
+# DIB image OS release. Default is "8".
 #kolla_bifrost_dib_os_release:
 
-# List of default DIB elements.
+# List of default DIB elements. Default is ["disable-selinux",
+# "enable-serial-console", "vm"].
 #kolla_bifrost_dib_elements_default:
 
-# List of additional DIB elements.
+# List of additional DIB elements. Default is none.
 #kolla_bifrost_dib_elements_extra:
 
-# List of DIB elements.
+# List of DIB elements. Default is a combination of
+# kolla_bifrost_dib_elements_default and kolla_bifrost_dib_elements_extra.
 #kolla_bifrost_dib_elements:
 
-# DIB init element.
+# DIB init element. Default is "cloud-init-datasources".
 #kolla_bifrost_dib_init_element:
 
-# DIB default environment variables.
+# DIB default environment variables. Default is {"DIB_CLOUD_INIT_DATASOURCES":
+# "ConfigDrive", "DIB_DISABLE_KERNEL_CLEANUP": 1}.
 #kolla_bifrost_dib_env_vars_default:
 
-# DIB additional environment variables.
+# DIB additional environment variables. Default is none.
 #kolla_bifrost_dib_env_vars_extra:
 
-# DIB environment variables.
+# DIB environment variables. Default is combination of
+# kolla_bifrost_dib_env_vars_default and kolla_bifrost_dib_env_vars_extra.
 #kolla_bifrost_dib_env_vars:
 
-# List of DIB packages to install.
+# List of DIB packages to install. Default is to install no extra packages.
 #kolla_bifrost_dib_packages:
 
 ###############################################################################
diff --git a/etc/kayobe/seed-vm.yml b/etc/kayobe/seed-vm.yml
index 897fe49b8..4e33cb01e 100644
--- a/etc/kayobe/seed-vm.yml
+++ b/etc/kayobe/seed-vm.yml
@@ -23,7 +23,8 @@
 # Format of the seed VM root volume.
 #seed_vm_root_format:
 
-# Base image for the seed VM root volume.
+# Base image for the seed VM root volume. Default is
+# "https://cloud.centos.org/centos/8/x86_64/images/CentOS-8-GenericCloud-8.1.1911-20200113.3.x86_64.qcow2".
 #seed_vm_root_image:
 
 # Capacity of the seed VM data volume.
diff --git a/requirements.yml b/requirements.yml
index 17baff303..d08b92a3e 100644
--- a/requirements.yml
+++ b/requirements.yml
@@ -3,7 +3,7 @@
   version: 1.3.1
 - src: jriguera.configdrive
   # There are no versioned releases of this role.
-  version: 6b5f1d55bc3f27fa2855d8dd59b5c224d160d806
+  version: a5c3c19d0cda7b6960c9200a30b5dbe73d2eef96
 - src: MichaelRigart.interfaces
   version: v1.4.0
 - src: mrlesmithjr.manage-lvm
@@ -24,9 +24,9 @@
 - src: stackhpc.grafana-conf
   version: 1.1.0
 - src: stackhpc.libvirt-host
-  version: v1.3.1
+  version: v1.7.0
 - src: stackhpc.libvirt-vm
-  version: v1.10.0
+  version: v1.13.0
 - src: stackhpc.mellanox-switch
   version: v1.0.0
 - src: stackhpc.os-images