Merge pull request #75 from pierresouchay/fix_issue_74

Added new utility methods to fix #74

TemplateAPI.md

@@ -380,6 +380,15 @@ Full example: [samples/consul_template.txt.erb](samples/consul_template.txt.erb)
 [List all the services of a given Node](https://www.consul.io/api/catalog.html#list-services-for-node) using its
 name or its ID. If DC is specified, will lookup for given node in another datacenter.
 
+The value returned might be nil (because the node does not exists).
+Thus, it might be safer to use the helper methods on the result:
+
+ * node('mynode').exists? -> true if node exists and result is not nil
+ * node('mynode').services() -> to get the hash of services defined for this node (return empty map if nodes does not exists)
+ * node('mynode').node() -> to get node information (empty map if node does not exists)
+
+ See also: https://github.com/criteo/consul-templaterb/issues/74
+
 ## checks_for_node(name, dc: nil, passing: false, tag: nil, [agent: consul_agent_address])
 
 [Find all the checks](https://www.consul.io/api/health.html#list-checks-for-node) of a given node name.

lib/consul/async/consul_template.rb

@@ -187,7 +187,7 @@ def node(name_or_id, dc: nil, agent: nil)
         path = "/v1/catalog/node/#{name_or_id}"
         query_params = {}
         query_params[:dc] = dc if dc
-        create_if_missing(path, query_params, agent: agent) { ConsulTemplateNodes.new(ConsulEndpoint.new(consul_conf, path, true, query_params, '{}', agent)) }
+        create_if_missing(path, query_params, agent: agent) { ConsulTemplateNode.new(ConsulEndpoint.new(consul_conf, path, true, query_params, '{}', agent)) }
       end
 
       # https://www.consul.io/api/agent.html#read-configuration
@@ -628,6 +628,36 @@ def initialize(consul_endpoint)
       end
     end
 
+    # Get information about a single node
+    class ConsulTemplateNode < ConsulTemplateAbstractMap
+      def initialize(consul_endpoint)
+        super(consul_endpoint)
+      end
+
+      def exists?
+        !result_delegate.nil?
+      end
+
+      def safe_get
+        if exists?
+          result_delegate
+        else
+          {
+            'Node': {},
+            'Services': {}
+          }
+        end
+      end
+
+      def node
+        safe_get['Node'] || {}
+      end
+
+      def services
+        safe_get['Services'] || {}
+      end
+    end
+
     # List of nodes of the whole cluster
     class ConsulTemplateNodes < ConsulTemplateAbstractArray
       def initialize(consul_endpoint)

spec/consul/async/async_mock.rb

@@ -50,6 +50,7 @@ def mock_consul
          v1/catalog/datacenters
          v1/catalog/nodes
          v1/catalog/node/consul02.prod
+         v1/catalog/node/does_not_exists
          v1/catalog/node/7a985997-3925-4f18-8613-637c81bd750b
          v1/catalog/services
          v1/coordinate/datacenters

spec/consul/async/resources/consul/v1/catalog/node/7a985997-3925-4f18-8613-637c81bd750b.json

@@ -1,16 +1,19 @@
 {
-  "ID": "7a985997-3925-4f18-8613-637c81bd750b",
-  "Node": "consul02.prod",
-  "Address": "10.251.1.96",
-  "Datacenter": "par",
-  "TaggedAddresses": {
-    "lan": "10.251.1.96",
-    "wan": "10.251.1.96"
+  "Node":{
+    "ID": "7a985997-3925-4f18-8613-637c81bd750b",
+    "Node": "consul02.prod",
+    "Address": "10.251.1.96",
+    "Datacenter": "par",
+    "TaggedAddresses": {
+      "lan": "10.251.1.96",
+      "wan": "10.251.1.96"
+    },
+    "Meta": {
+      "consul-network-segment": "",
+      "rack_name": "2207"
+    },
+    "CreateIndex": 228090242,
+    "ModifyIndex": 228091668
   },
-  "Meta": {
-    "consul-network-segment": "",
-    "rack_name": "2207"
-  },
-  "CreateIndex": 228090242,
-  "ModifyIndex": 228091668
+  "Services": {}
 }

spec/consul/async/resources/consul/v1/catalog/node/consul02.prod.json

@@ -1,16 +1,19 @@
 {
-  "ID": "7a985997-3925-4f18-8613-637c81bd750b",
-  "Node": "consul02.prod",
-  "Address": "10.251.1.96",
-  "Datacenter": "par",
-  "TaggedAddresses": {
-    "lan": "10.251.1.96",
-    "wan": "10.251.1.96"
+  "Node": {
+    "ID": "7a985997-3925-4f18-8613-637c81bd750b",
+    "Node": "consul02.prod",
+    "Address": "10.251.1.96",
+    "Datacenter": "par",
+    "TaggedAddresses": {
+      "lan": "10.251.1.96",
+      "wan": "10.251.1.96"
+    },
+    "Meta": {
+      "consul-network-segment": "",
+      "rack_name": "2207"
+    },
+    "CreateIndex": 228090242,
+    "ModifyIndex": 228091668
   },
-  "Meta": {
-    "consul-network-segment": "",
-    "rack_name": "2207"
-  },
-  "CreateIndex": 228090242,
-  "ModifyIndex": 228091668
+  "Services": {}
 }

spec/consul/async/resources/consul/v1/catalog/node/does_not_exists.json

@@ -0,0 +1 @@
+null

spec/consul/async/resources/templates/unit_nodes.erb

@@ -5,5 +5,12 @@ Nodes
 <%
   end
 %>
-Node: <%= node('consul02.prod')['Node'] %>
-ID: <%= node('7a985997-3925-4f18-8613-637c81bd750b')['ID'] %>
+Helper when exists:
+Node: <%= node('consul02.prod').node['Node'] %>
+ID: <%= node('7a985997-3925-4f18-8613-637c81bd750b').node['ID'] %>
+exists? <%= node('consul02.prod').exists? %>
+
+Helpes when does not exists:
+* exists? = <%= node("does_not_exists").exists? %>
+* node empty = <%= node("does_not_exists").node == {} %>
+* services empty <%= node("does_not_exists").services == {} %>

spec/consul/async/resources/templates/unit_nodes.txt.expected

@@ -4,5 +4,12 @@ consul02.prod
 consul03.prod
 consul04.prod
 
+Helper when exists:
 Node: consul02.prod
 ID: 7a985997-3925-4f18-8613-637c81bd750b
+exists? true
+
+Helpes when does not exists:
+* exists? = false
+* node empty = true
+* services empty true