Allow artifact_file to handle snapshot and latest version correctly

README.md

@@ -133,6 +133,7 @@ location               | The location to the artifact file. Either a nexus ident
 checksum               | The SHA256 checksum for verifying URL downloads. Not used when location is Nexus     | String  |
 owner                  | Owner of the downloaded file                                                         | String  |
 group                  | Group of the downloaded file                                                         | String  |
+symlink                | If specified (absolute path), creates a symlink pointing to the downloaded artifact  | String  |
 after_download         | A proc containing resources to be executed only if the artifact has been downloaded  | Proc    |
 download_retries       | The number of times to attempt to download the file if it fails its integrity check  | Integer | 1
 
@@ -446,6 +447,19 @@ Your data_bag can contain both ```nexus``` and ```aws``` configuration.
   resource. For example, when force is true, you can also change the value of owner and group to remap the deployed artifact to
   a new permissions scheme.
 
+##### Using artifact_file to download lastest artifact from Nexus
+
+    artifact_file "/tmp/my-artifact.jar" do
+      location "com.test:my-artifact:tgz:LATEST"
+      owner "me"
+      group "mes"
+      symlink "/tmp/my-artifact-LATEST.jar"
+      action :create
+    end
+
+  In this case, LWRP can't guess artifact filename during runtime, so we are not able to know the final artifactname.
+  Adding a symlink to the file allow to always have a static file pointing to latest downloaded version.
+
 ##### Using artifact_file to download a file from an S3 bucket
 
     artifact_file "/tmp/my-artifact.tgz" do

libraries/chef_artifact_nexus.rb

@@ -55,6 +55,16 @@ def retrieve_from_nexus(source, destination_dir)
       def get_artifact_sha(coordinates)
         REXML::Document.new(remote.get_artifact_info(coordinates)).elements["//sha1"].text
       end
+
+      # Makes a call to Nexus and parses the returned XML to return
+      # the Nexus Server's stored filename (with ext) for the given artifact.
+      #
+      # @param  coordinates [String] a colon-separated Maven identifier that represents the artifact
+      #
+      # @return [String] the filename for the artifact
+      def get_artifact_filename(coordinates)
+        ::File.basename(REXML::Document.new(remote.get_artifact_info(coordinates)).elements["//repositoryPath"].text)
+      end
     end
   end
 end

providers/file.rb

@@ -37,6 +37,16 @@ def load_current_resource
 
     @nexus_configuration = new_resource.nexus_configuration
     @nexus_connection = Chef::Artifact::Nexus.new(node, nexus_configuration)
+
+    if Chef::Artifact.snapshot?(new_resource.location.split(':')[-1]) || Chef::Artifact.latest?(new_resource.location.split(':')[-1])
+      Chef::Log.info "#{new_resource.name} is a rolling/snapshot version - filename is retrieved from metadata, existing name is ignored"
+      dest_filepath = ::File.join(
+        ::File.dirname(new_resource.path),
+        @nexus_connection.get_artifact_filename(new_resource.location)
+      )
+      new_resource.path(dest_filepath)
+    end
+
   elsif Chef::Artifact.from_s3?(@new_resource.location)
     chef_gem "aws-sdk" do
       version "1.29.0"
@@ -71,6 +81,7 @@ def load_current_resource
       remote_file_resource.run_action(:create)
     end
     raise Chef::Artifact::ArtifactChecksumError unless checksum_valid?
+    create_symlink if new_resource.symlink
     write_checksum if Chef::Artifact.from_nexus?(file_location) || Chef::Artifact.from_s3?(file_location)
   rescue Chef::Artifact::ArtifactChecksumError => e
     if retries > 0
@@ -178,3 +189,15 @@ def write_checksum
   def read_checksum
     ::File.read(cached_checksum).strip
   end
+
+  # Manage a symlink pointing to artifact downloaded file
+  # Symlink attr should specify absolute symlink path
+  #
+  # @return [NilClass] the created path
+  def create_symlink
+    link new_resource.symlink do
+      to new_resource.path
+      owner new_resource.owner
+      group new_resource.group
+    end
+  end

resources/file.rb

@@ -27,6 +27,7 @@
 attribute :checksum, :kind_of  => String
 attribute :owner, :kind_of => String, :required => true, :regex => Chef::Config[:user_valid_regex]
 attribute :group, :kind_of => String, :required => true, :regex => Chef::Config[:user_valid_regex]
+attribute :symlink, :kind_of => String
 attribute :download_retries, :kind_of => Integer, :default => 1
 attribute :after_download, :kind_of => Proc
 attribute :nexus_configuration, :kind_of => Chef::Artifact::NexusConfiguration, :default => Chef::Artifact::NexusConfiguration.from_data_bag