So here is my use case, I have a two nodes which have to be configured to know about each other, but I can’t use multicast, and I want to be elastic, in that I can add a node and the others configs get updated. So to start we are going to have two nodes, gateway1 and gateway2, and each has a config file called sipmethod.xml which contains a node of XML data that defines the cluster.
<Cluster>
<Node name="gateway2" local="10.72.111.116:47520">
<Peer remote="10.110.234.150:47520"/>
</Node>
</Cluster>and here is my template that creates this section (sorta):
<% if node[:prism][:sipmethod][:cluster] %>
<Cluster>
<Node name="<%=node[:hostname]%>" local="<%=node[:ipaddress]%>:<%= node[:prism][:sipenv][:rmi_port] %>">
<% search(:node, "role:rayo_gateway AND chef_environment:#{node.chef_environment}").each do |peer| %>
<Peer remote="<%= (peer.ec2 ? peer.ec2.local_ipv4 : peer.ipaddress) %>:<%= node[:prism][:sipenv][:rmi_port] %>"/>
<%end%>
</Node>
</Cluster>
<%end%>Now there is one problem with this approach, if you look carefully the peers are going to include itself, which is not going to work.
<Cluster>
<Node name="gateway2" local="10.72.111.116:47520">
<Peer remote="10.110.234.150:47520"/>
<Peer remote="10.72.111.116:47520"/> <!-- PROBLEM -->
</Node>
</Cluster>I need to not include the node running the search in the results, and this is actually pretty simple:
We are going to take this search and simply add a NOT clause:
search(:node, "role:rayo_gateway AND chef_environment:#{node.chef_environment} NOT name:#{node.name}")This will result in returning every gateway in my environment except the one running the search, and the end result is the dynamically configured cluster config:
<Cluster>
<Node name="gateway2" local="10.72.111.116:47520">
<Peer remote="10.110.234.150:47520"/>
</Node>
</Cluster>