Add a custom resource to set up PostgreSQL 12

Supports both primary and replica. The access rules and firewall have to
be set up outside of the custom resource, so they are part of the
recipes instead

Refs #160

site-cookbooks/kosmos-postgresql/libraries/helpers.rb

@@ -0,0 +1,33 @@
+class Chef
+  class Recipe
+    def postgresql_primary
+      postgresql_primary = search(:node, "role:postgresql_primary AND chef_environment:#{node.chef_environment}").first
+
+      unless postgresql_primary.nil?
+        primary_ip = ip_for(postgresql_primary)
+
+        { hostname: postgresql_primary[:hostname], ipaddress: primary_ip }
+      end
+    end
+
+    def postgresql_replicas
+      postgresql_replicas = []
+
+      search(:node, "role:postgresql_replica AND chef_environment:#{node.chef_environment}").each do |replica|
+        replica_ip = ip_for(replica)
+
+        postgresql_replicas << { hostname: replica[:hostname], ipaddress: replica_ip }
+      end
+
+      postgresql_replicas
+    end
+
+    def ip_for(server_node)
+      if node.chef_environment == "development"
+        server_node['network']['interfaces']['eth1']['routes'].first['src']
+      else
+        server_node['ipaddress']
+      end
+    end
+  end
+end