Add check_script for haproxy in keepalived

This patch checks that haproxy is alive and running. It does this by
using socat to talk to the haproxy socket. That socket will only
respond successfully when haproxy is active and functional.

Change-Id: I528588d5742071103c28109a69842a6f935232c2
Closes-Bug: #1478570

ansible/roles/haproxy/tasks/start.yml

@@ -6,6 +6,7 @@
     container_privileged: "True"
     container_volumes:
       - "{{ node_config_directory }}/keepalived/:/opt/kolla/keepalived/:ro"
+      - "/run:/run"
     container_environment:
       KOLLA_CONFIG_STRATEGY: "{{ config_strategy }}"
 
@@ -15,6 +16,7 @@
     container_name: "haproxy"
     container_volumes:
       - "{{ node_config_directory }}/haproxy/:/opt/kolla/haproxy/:ro"
+      - "/run:/run"
     container_environment:
       KOLLA_CONFIG_STRATEGY: "{{ config_strategy }}"
 

ansible/roles/haproxy/templates/haproxy.cfg.j2

@@ -1,10 +1,10 @@
 global
   daemon
   maxconn 4000
+  stats socket /run/haproxy.sock
 
 defaults
   mode http
-  maxconn 4000
   option redispatch
   retries 3
   timeout http-request 10s

ansible/roles/haproxy/templates/keepalived.conf.j2

@@ -1,7 +1,8 @@
 vrrp_script check_alive {
     script "/check_alive.sh"
     interval 2
-    weight -10
+    fall 2
+    rise 10
 }
 
 vrrp_instance Floating {

docker/common/keepalived/check_alive.sh

@@ -1,7 +1,6 @@
 #!/bin/bash
 
-# This is noop check script. Change it to something meaningful.
-# TODO (inc0): When HAProxy is implemented, this should be changed to HAProxy check
-# https://github.com/stackforge/kolla/blob/master/specs/high-availability.rst
+# This will return 0 when it successfully talks to the haproxy daemon via the socket
+# Failures return 1
 
-exit 0
+echo "show info" | socat unix-connect:/run/haproxy.sock stdio