Added post and pre hook script for veth cleanup

The change adds a simple post and pre hook script to clean up all of the
the named veth pairs that are assosiated within a given container.

Change-Id: I563a4be9f5e04c1599a9e4e592970a4ef0dbb38e
Implements: blueprint named-veths

playbooks/roles/lxc_container_create/tasks/container_create.yml

@@ -214,6 +214,34 @@
   tags:
     - lxc-container-networks
 
+# Adds post-down and pre-start hooks
+- name: Drop veth cleanup script
+  template:
+    src: "veth-cleanup.sh.j2"
+    dest: "/var/lib/lxc/{{ inventory_hostname }}/veth-cleanup.sh"
+    owner: "root"
+    group: "root"
+    mode: "0755"
+  delegate_to: "{{ physical_host }}"
+  tags:
+    - lxc-container-networks
+
+# This is being defined due to an issue with dangling veth pairs.
+#  TODO(someone) This should be removed once an upstream patch has
+#  been submitted to either the kernel or LXC to fix the veth issues.
+#  Container restart is not happening here because it's not needed.
+- name: Defines a pre and post hook script
+  lineinfile:
+    dest: "/var/lib/lxc/{{ inventory_hostname }}/config"
+    line: "{{ item }}"
+    backup: "true"
+  with_items:
+    - "lxc.hook.pre-start = /var/lib/lxc/{{ inventory_hostname }}/veth-cleanup.sh"
+    - "lxc.hook.post-stop = /var/lib/lxc/{{ inventory_hostname }}/veth-cleanup.sh"
+  delegate_to: "{{ physical_host }}"
+  tags:
+    - lxc-container-networks
+
 # Flush the handlers to ensure the container and networking is online.
 - meta: flush_handlers
 

playbooks/roles/lxc_container_create/templates/veth-cleanup.sh.j2

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+
+# LXC eth0 is considered special and not managed by the base container_networks
+#  data structure. This is being added outside of the loop for this reason.
+ip link del {{ inventory_hostname[-8:].replace('-', '').replace('_', '') }}_eth0 || true
+logger "LXC container {{ inventory_hostname }} removing veth {{ inventory_hostname[-8:].replace('-', '').replace('_', '') }}_eth0"
+
+# Veth cleanup for items in the container_networks data structure
+{% for key, value in container_networks.items() %}
+ip link del {{ inventory_hostname[-8:].replace('-', '').replace('_', '') }}_{{ value.interface }} || true
+logger "LXC container {{ inventory_hostname }} removing veth {{ inventory_hostname[-8:].replace('-', '').replace('_', '') }}_{{ value.interface }}"
+
+{% endfor %}