Add __PARAMETER__, __CLASS__ and __MODULE__ tags (crayfishx#62)

* Added __PARAMETER__, __CLASS__ and __MODULE__ tags

Author: crayfishx

.gitignore

@@ -0,0 +1 @@
+Gemfile.lock

README.md

@@ -59,7 +59,7 @@ The following mandatory Hiera 5 options must be set for each level of the hierar
 
 `name`: A human readable name for the lookup
 `lookup_key`: This option must be set to `hiera_http`
-`uris` or `uri`: An array of URI's passed to `uris` _or_ a single URI passed to `uri`
+`uris` or `uri`: An array of URI's passed to `uris` _or_ a single URI passed to `uri`. This option supports interpolating special tags, see below.
 
 
 The following are optional configuration parameters supported in the `options` hash of the Hiera 5 config
@@ -98,12 +98,16 @@ The following are optional configuration parameters supported in the `options` h
 
 `:headers:`: Hash of headers to send in the request
 
-### Using the key name as part of the URI
+### Interpolating special tags
 
-Previous versions of this backed allowed the use of `%{key}` to include the key
-name as part of the URL. Due to API changes in Hiera v5, this interpolation is
-no longer possible. This backend now supports an alternative method to include
-the key name using the `__KEY__` tag.
+Previous versions of this backed allowed the use of variables such as `%{key}` and `%{calling_module}` to be used in the URL, this has changed with Hiera 5. To allow for similar behaviour you can use a number of tags surrounded by `__` to interpolate special variables derived from the key into the `uri` or `uris` option in hiera.yaml. Currently you can interpolate `__KEY__`, `__MODULE__`, `__CLASS__` and `__PARAMETER__`, these tags are derived from parsing the original lookup key.
+
+In the case of a lookup key matching `foo::bar::tango` the following tags are available;
+
+* `__KEY__` : The original lookup key unchanched; `foo::bar::tango`
+* `__MODULE__` : The first part of the lookup key; `foo`
+* `__CLASS__` : All but the last parts of the lookup key; `foo::bar`
+* `__PARAMETER__` : The last part of they key representing the class parameter; `tango`
 
 Example using this backend to interact with the [Puppet Enterprise Jenkins Pipeline plugin](https://wiki.jenkins.io/display/JENKINS/Puppet+Enterprise+Pipeline+Plugin)
 
@@ -124,10 +128,6 @@ hierarchy:
     options:
       output: json
       failure: graceful
-#      use_auth: true
-#     auth_user: ''
-#     auth_pass: ''
-
 ```
 
 ### Author

lib/puppet/functions/hiera_http.rb

@@ -27,14 +27,33 @@ def lookup_key(key, options, context)
       end
     end
 
-    options['uri'].gsub! '__KEY__', key
+    options['uri'] = parse_tags(key, options['uri'])
     result = http_get(context, options)
 
     answer = result.is_a?(Hash) ? result[key] : result
     context.not_found if answer.nil?
     return answer
   end
 
+  def parse_tags(key,uri)
+    key_parts = key.split(/::/)
+    parsed_uri = uri.gsub(/__(\w+)__/i) { |tag|
+        case tag
+        when '__KEY__'
+          key
+        when '__MODULE__'
+          key_parts.first if key_parts.length > 1
+        when '__CLASS__'
+          key_parts[0..-2].join('::') if key_parts.length > 1
+        when '__PARAMETER__'
+          key_parts.last
+        end
+    }
+    return parsed_uri
+  end
+
+
+
   def http_get(context, options)
     uri = URI.parse(options['uri'])
     host, port, path = uri.host, uri.port, URI.escape(context.interpolate(uri.request_uri))

spec/functions/hiera_http_spec.rb

@@ -40,6 +40,36 @@
         expect(@lookuphttp).to receive(:get_parsed).with('/path/foo::bar::tango')
         function.lookup_key('foo::bar::tango', options, @context)
       end
+
+      it "should interpolate __MODULE__ correctly" do
+        options = { 'uri' => 'http://localhost/path/__MODULE__' }
+        expect(@context).to receive(:interpolate).with('/path/foo').and_return('/path/foo')
+        expect(@lookuphttp).to receive(:get_parsed).with('/path/foo')
+        function.lookup_key('foo::bar::tango', options, @context)
+      end
+
+      it "should interpolate __CLASS__ correctly" do
+        options = { 'uri' => 'http://localhost/path/__CLASS__' }
+        expect(@context).to receive(:interpolate).with('/path/foo::bar').and_return('/path/foo::bar')
+        expect(@lookuphttp).to receive(:get_parsed).with('/path/foo::bar')
+        function.lookup_key('foo::bar::tango', options, @context)
+      end
+
+      it "should interpolate __PARAMETER__ correctly" do
+        options = { 'uri' => 'http://localhost/path/__PARAMETER__' }
+        expect(@context).to receive(:interpolate).with('/path/tango').and_return('/path/tango')
+        expect(@lookuphttp).to receive(:get_parsed).with('/path/tango')
+        function.lookup_key('foo::bar::tango', options, @context)
+      end
+
+      it "should interpolate more than one field" do
+        options = { 'uri' => 'http://localhost/path/__MODULE__/__PARAMETER__/__PARAMETER__' }
+        expect(@context).to receive(:interpolate).with('/path/foo/tango/tango').and_return('/path/foo/tango/tango')
+        expect(@lookuphttp).to receive(:get_parsed).with('/path/foo/tango/tango')
+        function.lookup_key('foo::bar::tango', options, @context)
+      end
+
+
     end
 
     context "When confine_to_keys is set" do