Support new virtual_interfaces definition for VIPs

Prior to this change, the keepalived element only allowed for a single
keepalive interface. This could be problematic if, for instance,
keepalive is managing several VIPs which are on different broadcast
domains - for instance, because one vip is on an interface/vlan that's
accessible to the public, while another is on an interface/vlan that's
only accessible within the cloud.

This change allows for a more flexible configuration in which multiple
vrrp instances can be defined in heat- each with their own interface,
router_id, and set of virtual IPs.

This patchset partially completes a spec which will one day live at
https://blueprints.launchpad.net/tripleo/+specs/tripleo-juno-virtual-public-ips
but for now can bee seen in  Id9addc65f0d2ed519ce4b3edbd561ed660a2786e

Removed the check weight configuration as vrrp_sync_groups and and
check_script weights are mutually exclusive configurations. Regardless,
based on
https://github.com/acassen/keepalived/blob/master/doc/keepalived.conf.SYNOPSIS#L103
the default weight is automatically set to 2 if not specified.

Change-Id: I5f04cee6c84ce7ad6e258c489088a47f00a53fda
Co-authored-by: Julia Kreger <juliaashleykreger@gmail.com>

elements/keepalived/README.md

@@ -3,6 +3,8 @@ Element to install keepalived
 Configuration
 -------------
 
+Configuration can be provided two ways: the simpler, deprecated, way:
+
     keepalived:
       # interface used for VRRP traffic
       keepalive_interface: eth0
@@ -12,3 +14,27 @@ Configuration
         interface: eth0
       - ip: fe80::5cc1:afff:fe58:143b/64
         interface: br-ctlplane
+
+or the more detailed newer way for more complicated setups. If both ``virtual_interfaces`` and ``keepalived`` keys are present, the latter is ignored.
+
+    virtual_interfaces:
+      instances:
+        - vrrp_instance_name: VI_CONTROL
+          virtual_router_id: 51
+          keepalive_interface: eth0
+          priority: 101
+          virtual_ips:
+          - ip: 192.0.2.254/24
+            interface: eth0
+        - vrrp_instance_name: VI_PUBLIC
+          virtual_router_id: 52
+          keepalive_interface: eth0
+          priority: 101
+          virtual_ips:
+          - ip: 10.16.15.154/24
+            interface: vlan25
+      vrrp_sync_groups:
+        - name: VG1
+          members:
+            - VI_CONTROL
+            - VI_PUBLIC

elements/keepalived/os-apply-config/etc/keepalived/keepalived.conf

@@ -1,9 +1,38 @@
 vrrp_script chk_haproxy {
       script "killall -0 haproxy"
       interval 2
-      weight 2
 }
 
+{{#virtual_interfaces}}
+{{#instances}}
+vrrp_instance {{vrrp_instance_name}} {
+      interface {{keepalive_interface}}
+      state MASTER
+      virtual_router_id {{virtual_router_id}}
+      priority {{priority}}
+      virtual_ipaddress {
+           {{#virtual_ips}}
+           {{ip}} dev {{interface}}
+           {{/virtual_ips}}
+      }
+      track_script {
+           chk_haproxy
+      }
+}
+
+{{/instances}}
+
+{{#vrrp_sync_groups}}
+vrrp_sync_group {{name}}
+  group {
+    {{#members}}
+    {{.}}
+    {{/members}}
+  }
+{{/vrrp_sync_groups}}
+{{/virtual_interfaces}}
+
+{{^virtual_interfaces}}
 vrrp_instance VI_1 {
       interface {{keepalived.keepalive_interface}}
       state MASTER
@@ -18,3 +47,4 @@ vrrp_instance VI_1 {
            chk_haproxy
       }
 }
+{{/virtual_interfaces}}