diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index ebe619f5a..88ce29324 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -134,3 +134,25 @@ You can select what to delete prior to the run of quickstart adding a
 -  all: same as virthost but user setup in virthost is deleted too
 -  none: will not teardown anything (useful for testing multiple actions
    against a deployed overcloud)
+
+Undercloud customization
+------------------------
+
+You can perform extra undercloud customization steps, using a script
+that will be applied with ``virt-customize`` on the final undercloud
+image. To allow that, you need to pass the ``undercloud_customize_script``
+var, that needs to point to an script living on your filesystem.
+That script will be copied to working directory, and applied on the
+undercloud. The script can be in Jinja template format, so you can benefit
+from ansible var substitutions.
+
+Overcloud customization
+-----------------------
+
+You can perform extra overclud customization steps, using a script
+that will be applied with ``virt-customize`` on the overcloud-full
+image. To allow that, you need to pass the ``overcloud_customize_script``
+var, that needs to point to an script living on your filesystem.
+That script will be copied to working directory, and applied on the
+overcloud. The script can be in Jinja template format, so you can benefit
+from ansible var substitutions.
diff --git a/roles/libvirt/setup/undercloud/tasks/customize_overcloud.yml b/roles/libvirt/setup/undercloud/tasks/customize_overcloud.yml
new file mode 100644
index 000000000..ab35d44df
--- /dev/null
+++ b/roles/libvirt/setup/undercloud/tasks/customize_overcloud.yml
@@ -0,0 +1,38 @@
+- name: Create overcloud customize script
+  template:
+    src: "{{ overcloud_customize_script }}"
+    dest: "{{ working_dir }}/overcloud-customize.sh"
+    mode: 0755
+
+- environment:
+    LIBGUESTFS_BACKEND: direct
+    LIBVIRT_DEFAULT_URI: "{{ libvirt_uri }}"
+  block:
+  # We need to extract the overcloud image, if it's not already extracted.
+  # so we can inject the gating repo into it.
+  - name: check if overcloud image is already extracted
+    stat:
+      path: '{{ working_dir }}/overcloud-full.qcow2'
+    register: overcloud_image_stat_for_customize
+
+  - name: Extract overcloud-full image
+    command: >
+      virt-copy-out -a {{ working_dir }}/undercloud.qcow2
+      /home/stack/overcloud-full.qcow2 {{ working_dir }}
+    register: overcloud_image_extracted_for_customize
+    when: not overcloud_image_stat_for_customize.stat.exists
+
+  # only customize overcloud-full image if that is not going to be
+  # used as undercloud
+  - name: Perform extra overcloud customizations
+    command: >
+      virt-customize -a {{ working_dir}}/overcloud-full.qcow2
+      --run '{{ working_dir}}/overcloud-customize.sh'
+
+  - name: Copy updated overcloud-full image back to undercloud
+    command: >
+      virt-copy-in -a {{ working_dir }}/undercloud.qcow2
+      {{ working_dir }}/overcloud-full.qcow2 /home/stack/
+    when: overcloud_image_extracted_for_customize is defined and
+          overcloud_image_extracted_for_customize|changed
+
diff --git a/roles/libvirt/setup/undercloud/tasks/main.yml b/roles/libvirt/setup/undercloud/tasks/main.yml
index 4f2200202..51f1a0757 100644
--- a/roles/libvirt/setup/undercloud/tasks/main.yml
+++ b/roles/libvirt/setup/undercloud/tasks/main.yml
@@ -87,6 +87,27 @@
         owner: stack
         group: stack
 
+  - name: Create undercloud customize script
+    template:
+      src: "{{ undercloud_customize_script }}"
+      dest: "{{ working_dir}}/undercloud-customize.sh"
+      mode: 0755
+    when: undercloud_customize_script is defined
+
+  # This allows to run a customization script on the
+  # undercloud image, to cover any extra needs.
+  - name: Perform extra undercloud customizations
+    command: >
+      virt-customize -a {{ working_dir }}/undercloud.qcow2
+      --run '{{ working_dir }}/undercloud-customize.sh'
+    when: undercloud_customize_script is defined
+
+  # This allows to run a customization script on the
+  # overcloud image, to cover any extra needs.
+  - name: Perform extra overcloud customizations
+    include: customize_overcloud.yml
+    when: overcloud_customize_script is defined
+
   # Perform an SELinux relabel on the undercloud image to avoid problems
   # caused by bad labelling, since by default the undercloud runs in
   # enforcing mode.