AppDynamics Offline Configuration

Previously, when the offline configuration of AppDynamics was added, an
Internet Availability exception was not added.  This change adds that
exception allowing remote configuration to be downloaded even by offline
buildpacks.

[resolves #815]

Signed-off-by: Ben Hale <[email protected]>

Author: nebhale

lib/java_buildpack/framework/app_dynamics_agent.rb

@@ -171,20 +171,24 @@ def check_if_resource_exists(resource_uri, conf_file)
       def override_default_config_if_applicable
         return unless @application.environment['APPD_CONF_HTTP_URL']
 
-        agent_root = @application.environment['APPD_CONF_HTTP_URL'].chomp('/') + '/java/'
-        @logger.info { "Downloading override configuration files from #{agent_root}" }
-        CONFIG_FILES.each do |conf_file|
-          uri = URI(agent_root + conf_file)
-
-          # `download()` uses retries with exponential backoff which is expensive
-          # for situations like 404 File not Found. Also, `download()` doesn't expose
-          # an api to disable retries, which makes this check necessary to prevent
-          # long install times.
-          next unless check_if_resource_exists(uri, conf_file)
-
-          download(false, uri.to_s) do |file|
-            Dir.glob(@droplet.sandbox + 'ver*') do |target_directory|
-              FileUtils.cp_r file, target_directory + '/conf/' + conf_file
+        JavaBuildpack::Util::Cache::InternetAvailability.instance.available(
+          true, 'The AppDynamics remote configuration download location is always accessible'
+        ) do
+          agent_root = @application.environment['APPD_CONF_HTTP_URL'].chomp('/') + '/java/'
+          @logger.info { "Downloading override configuration files from #{agent_root}" }
+          CONFIG_FILES.each do |conf_file|
+            uri = URI(agent_root + conf_file)
+
+            # `download()` uses retries with exponential backoff which is expensive
+            # for situations like 404 File not Found. Also, `download()` doesn't expose
+            # an api to disable retries, which makes this check necessary to prevent
+            # long install times.
+            next unless check_if_resource_exists(uri, conf_file)
+
+            download(false, uri.to_s) do |file|
+              Dir.glob(@droplet.sandbox + 'ver*') do |target_directory|
+                FileUtils.cp_r file, target_directory + '/conf/' + conf_file
+              end
             end
           end
         end