Remove dependency on bridge-utils

bridge-utils is considered legacy and many distributions do
not ship it as default.

Change-Id: Id2f9d779d12a5135d7d7e7a4783c6f3a0c8647ca
Story: 2004302
Task: 27861

ansible/roles/veth-pair/README.md

@@ -15,9 +15,7 @@ This role manages a veth pair. Actions:
 Requirements
 ------------
 
-The host should have the `ip` and `ovs-vsctl` commands accessible. If
-`veth_pair_plug_into_source` is enabled, the command `brctl` must also be
-accessible.
+The host should have the `ip` and `ovs-vsctl` commands accessible.
 
 Role Variables
 --------------

ansible/roles/veth-pair/tasks/absent.yml

@@ -1,16 +1,17 @@
 ---
-- name: Unplug veth from source bridge
-  command: >-
-    brctl delif {{ veth_pair_source_bridge }}
-    {{ veth_pair_source_link_name }}
-  register: res
-  failed_when:
-    - res.rc != 0
-    # Case where veth is already unplugged.
-    - not (res.rc == 1 and 'does not exist' in res.stderr)
-  changed_when: res.rc == 0
+- block:
+  - include_tasks: is-attached.yml
+    vars:
+      bridge: "{{ veth_pair_source_bridge }}"
+      interface: "{{ veth_pair_source_link_name }}"
+
+  - name: Unplug veth from source bridge
+    command: >-
+      ip link set {{ veth_pair_source_link_name }} nomaster
+    when:
+      - veth_pair_is_attached
+    become: true
   when: veth_pair_plug_into_source | bool
-  become: true
 
 - name: Delete veth pair
   command: >-

ansible/roles/veth-pair/tasks/is-attached.yml

@@ -0,0 +1,22 @@
+---
+
+# This will determine if interface is attached to bridge and set a fact called
+# veth_pair_is_attached containing the result
+
+- name: Set a default value for veth_pair_is_attached
+  set_fact:
+    veth_pair_is_attached: false
+
+- name: Speculatively check {{ interface }}'s master
+  command: >-
+    realpath /sys/class/net/{{ interface }}/master
+  register: master_result
+  failed_when: false
+  changed_when: false
+
+- name: Determine if {{ interface }} is attached to {{ bridge }}
+  vars:
+    master: "{{ master_result.stdout | basename }}"
+  set_fact:
+    veth_pair_is_attached: "{{ master == bridge }}"
+  when: master_result.rc == 0

ansible/roles/veth-pair/tasks/present.yml

@@ -23,14 +23,17 @@
     port: "{{ veth_pair_ovs_link_name }}"
   become: true
 
-- name: Plug veth into source bridge
-  command: >-
-    brctl addif {{ veth_pair_source_bridge }}
-    {{ veth_pair_source_link_name }}
-  register: res
-  failed_when:
-    - res.rc != 0
-    - "'already a member of a bridge' not in res.stderr"
-  changed_when: "'already a member of a bridge' not in res.stderr"
+- block:
+  - include_tasks: is-attached.yml
+    vars:
+      bridge: "{{ veth_pair_source_bridge }}"
+      interface: "{{ veth_pair_source_link_name }}"
+
+  - name: Plug veth into source bridge
+    command: >-
+      ip link set {{ veth_pair_source_link_name }} master
+      {{ veth_pair_source_bridge }}
+    when:
+      - not veth_pair_is_attached
+    become: true
   when: veth_pair_plug_into_source | bool
-  become: true