Fix connectivity between multinode devstack jobs

To have connectivity through public network to the vms which are on
various nodes in the ci job, we need to configure special bridge called
"br-infra" and connect this bridge with br-ex with patch ports.
This can be done using "multi-node-bridge" role from zuul roles and
"multi-node-setup" added to this repository.

Change-Id: I80d7d2bed8291ba21ddc68b48fef5d0aac996b39

.pre-commit-config.yaml

@@ -2,7 +2,7 @@
 
 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.3.0
+    rev: v3.4.0
     hooks:
       - id: check-added-large-files
       - id: check-byte-order-marker

playbooks/multinode-setup.yaml

@@ -0,0 +1,3 @@
+- hosts: all
+  roles:
+    - multi-node-setup

roles/multi-node-setup/README.rst

@@ -0,0 +1,23 @@
+Set up connection between infra bridge and Neutron external bridge
+
+Network topology used in CI multinode jobs is described In `Devstack documention
+<https://opendev.org/openstack/devstack-gate/src/branch/master/multinode_setup_info.txt#L81>`_
+
+In case when DVR is used, there is also additional bridge ``br-infra`` added
+on each node to provide connectivity to floating IPs from main node.
+
+This bridge needs to be connected with bridge used by Neutron as
+external bridge. Typically it is ``br-ex`` and this role adds patch ports
+between those bridges.
+
+**Role Variables**
+
+.. zuul:rolevar:: neutron_external_bridge_name
+   :default: br-ex
+
+   Name of the Neutron external bridge.
+
+.. zuul:rolevar:: infra_bridge_name
+   :default: br-infra
+
+   Name of the infra bridge.

roles/multi-node-setup/defaults/main.yaml

@@ -0,0 +1,4 @@
+---
+
+infra_bridge_name: br-infra
+neutron_external_bridge_name: br-ex

roles/multi-node-setup/tasks/main.yaml

@@ -0,0 +1,32 @@
+---
+
+- name: Configure Neutron bridge for multi node setup
+  when: "( ansible_play_hosts | length ) > 1"
+  block:
+
+  - name: Ensure the infra bridge exists
+    become: true
+    openvswitch_bridge:
+      bridge: "{{ infra_bridge_name }}"
+      state: present
+      fail_mode: standalone
+
+  - name: Ensure the Neutron external bridge exists
+    become: true
+    openvswitch_bridge:
+      bridge: "{{ neutron_external_bridge_name }}"
+      state: present
+      fail_mode: standalone
+
+  - name: Create patch port between bridges
+    become: true
+    command: >-
+      ovs-vsctl
+        --may-exist add-port {{ infra_bridge_name }}
+          patch-{{ neutron_external_bridge_name }} --
+        set interface patch-{{ neutron_external_bridge_name }}
+          type=patch options:peer=patch-{{ infra_bridge_name }} --
+        --may-exist add-port {{ neutron_external_bridge_name }}
+          patch-{{ infra_bridge_name }} --
+        set interface patch-{{ infra_bridge_name }}
+          type=patch options:peer=patch-{{ neutron_external_bridge_name }}

zuul.d/jobs.yaml

@@ -228,6 +228,7 @@
     abstract: true
     description: Base DevStack Tobiko job with multinode.
     timeout: 10800
+    pre-run: playbooks/multinode-setup.yaml
     vars:
       topology: multinode
       devstack_localrc: