diff --git a/common/deploy-steps.j2 b/common/deploy-steps.j2
index 489c221a1c..78f4533354 100644
--- a/common/deploy-steps.j2
+++ b/common/deploy-steps.j2
@@ -102,6 +102,19 @@ resources:
           params:
             _TASKS: {get_file: deploy-steps-tasks.yaml}
 
+  ExternalDeployTasks:
+    type: OS::Heat::Value
+    properties:
+      type: comma_delimited_list
+      value:
+        yaql:
+          # processing from per-role unique tasks into globally unique tasks
+          expression: coalesce($.data, []).flatten().distinct()
+          data:
+          {%- for role in enabled_roles %}
+            - get_param: [role_data, {{role.name}}, external_deploy_tasks]
+          {%- endfor %}
+
 {%- for step in range(1, deploy_steps_max) %}
 # BEGIN workflow_tasks handling
   WorkflowTasks_Step{{step}}:
@@ -360,10 +373,21 @@ outputs:
                 - include: {{role.name}}/host_prep_tasks.yaml
                   when: role_name == '{{role.name}}'
 {%- endfor %}
+{%- for step in range(1,deploy_steps_max) %}
+            - hosts: undercloud
+              name: Undercloud deployment step {{step}}
+              vars:
+                step: '{{step}}'
+              tasks:
+                - include: external_deploy_steps_tasks.yaml
+            - hosts: overcloud
+              name: Overcloud deployment step {{step}}
+              vars:
+                bootstrap_server_id: BOOTSTRAP_SERVER_ID
+                step: '{{step}}'
+              tasks:
                 - include: deploy_steps_tasks.yaml
-                  with_sequence: count={{deploy_steps_max-1}}
-                  loop_control:
-                    loop_var: step
+{%- endfor %}
             - hosts: overcloud
               name: Server Post Deployments
               tasks:
@@ -374,6 +398,7 @@ outputs:
                   when: role_name == '{{role.name}}'
                   with_items: "{{ '{{' }} {{role.name}}_post_deployments|default([]) {{ '}}' }}"
 {%- endfor %}
+      external_deploy_steps_tasks: {get_attr: [ExternalDeployTasks, value]}
       update_steps_tasks: |
 {%- for role in roles %}
             - include: {{role.name}}/update_tasks.yaml
diff --git a/common/services.yaml b/common/services.yaml
index a0015c7eff..f82f425730 100644
--- a/common/services.yaml
+++ b/common/services.yaml
@@ -183,6 +183,16 @@ resources:
           expression: coalesce($.data.role_data, []).where($ != null).select($.get('workflow_tasks')).where($ != null).reduce($1.mergeWith($2), {})
           data: {role_data: {get_attr: [ServiceChain, role_data]}}
 
+  ExternalDeployTasks:
+    type: OS::Heat::Value
+    properties:
+      type: comma_delimited_list
+      value:
+        yaql:
+          # Note we use distinct() here to filter any identical tasks, e.g yum update for all services
+          expression: coalesce($.data, []).where($ != null).select($.get('external_deploy_tasks')).where($ != null).flatten().distinct()
+          data: {get_attr: [ServiceChain, role_data]}
+
   UpgradeTasks:
     type: OS::Heat::Value
     properties:
@@ -272,6 +282,7 @@ outputs:
       service_config_settings: {get_attr: [ServiceConfigSettings, value]}
       workflow_tasks: {get_attr: [WorkflowTasks, value]}
       step_config: {get_attr: [PuppetStepConfig, value]}
+      external_deploy_tasks: {get_attr: [ExternalDeployTasks, value]}
       upgrade_tasks: {get_attr: [UpgradeTasks, value]}
       post_upgrade_tasks: {get_attr: [PostUpgradeTasks, value]}
       update_tasks: {get_attr: [UpdateTasks, value]}
diff --git a/tools/yaml-validate.py b/tools/yaml-validate.py
index fcfa15e6c0..4fa6e0d4c1 100755
--- a/tools/yaml-validate.py
+++ b/tools/yaml-validate.py
@@ -48,7 +48,7 @@ OPTIONAL_DOCKER_SECTIONS = ['docker_puppet_tasks', 'upgrade_tasks',
                             'service_config_settings', 'host_prep_tasks',
                             'metadata_settings', 'kolla_config',
                             'global_config_settings', 'logging_source',
-                            'logging_groups']
+                            'logging_groups', 'external_deploy_tasks']
 REQUIRED_DOCKER_PUPPET_CONFIG_SECTIONS = ['config_volume', 'step_config',
                                           'config_image']
 OPTIONAL_DOCKER_PUPPET_CONFIG_SECTIONS = [ 'puppet_tags', 'volumes' ]