From 4c79cfa10b24296c84b95c84d101d79e64ab3022 Mon Sep 17 00:00:00 2001
From: Will Miller <willm@stackhpc.com>
Date: Wed, 22 Aug 2018 16:56:36 +0000
Subject: [PATCH] Add veth-pair role

This role configures a veth pair between an OVS bridge and another
device.
---
 ansible/roles/veth-pair/README.md         | 26 ++++++++++++++++++++
 ansible/roles/veth-pair/defaults/main.yml |  3 +++
 ansible/roles/veth-pair/tasks/main.yml    | 29 +++++++++++++++++++++++
 3 files changed, 58 insertions(+)
 create mode 100644 ansible/roles/veth-pair/README.md
 create mode 100644 ansible/roles/veth-pair/defaults/main.yml
 create mode 100644 ansible/roles/veth-pair/tasks/main.yml

diff --git a/ansible/roles/veth-pair/README.md b/ansible/roles/veth-pair/README.md
new file mode 100644
index 0000000..20fa351
--- /dev/null
+++ b/ansible/roles/veth-pair/README.md
@@ -0,0 +1,26 @@
+Veth Pair
+=========
+
+This role creates a veth pair. It will plug one end into the specified OVS
+bridge and, optionally, can plug the other end into a source Linux bridge.
+
+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.
+
+Role Variables
+--------------
+
+- `veth_pair_ovs_link_name`: The name to give the veth link that plugs into the
+  OVS bridge.
+- `veth_pair_ovs_bridge`: The name of the OVS bridge to plug into.
+- `veth_pair_source_link_name`: The name to give the veth link that plugs into
+  the source device.
+- `veth_pair_source_bridge`: The name of the source Linux bridge to plug into. Must be
+  specified if and only if `plug_into_source` is enabled.
+- `plug_into_source`: Whether or not to plug the source end of the veth pair
+  into a Linux bridge. If enabled, `source_bridge`, `source_bridge` must also
+  be specified. Default is `false`.
diff --git a/ansible/roles/veth-pair/defaults/main.yml b/ansible/roles/veth-pair/defaults/main.yml
new file mode 100644
index 0000000..0010742
--- /dev/null
+++ b/ansible/roles/veth-pair/defaults/main.yml
@@ -0,0 +1,3 @@
+---
+# Whether or not to plug the source end of the veth pair into a Linux bridge.
+veth_pair_plug_into_source: false
diff --git a/ansible/roles/veth-pair/tasks/main.yml b/ansible/roles/veth-pair/tasks/main.yml
new file mode 100644
index 0000000..dd4ba1e
--- /dev/null
+++ b/ansible/roles/veth-pair/tasks/main.yml
@@ -0,0 +1,29 @@
+---
+- name: Create veth pair
+  command: >
+    ip link add dev {{ veth_pair_ovs_link_name }}
+    type veth
+    peer name {{ veth_pair_source_link_name }}
+  register: res
+  changed_when: res.rc == 0
+  # Return code 2 means the veth pair already exists
+  failed_when: res.rc not in [0, 2]
+  become: true
+
+- name: Plug veth into OVS bridge
+  openvswitch_port:
+    bridge: "{{ veth_pair_ovs_bridge }}"
+    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"
+  when: veth_pair_plug_into_source | bool
+  become: true