Spring Insight service always available

The Spring Insight framework is different than all of the other
services because it downloads its dependency from the service itself,
rather than from a central location.  It does however honor the
Internet availability flag even though it doesn't go to the Internet.
This caused issues when an offline buildpack was used because it
prevented the proper dependency from being downloaded.

This change adds the ability to _temporarily_ override the value of
Internet availability so that the Spring Insight framework can always
download its dependencies, regardless of the current state of internet
connectivity.

[#70850900]

Author: nebhale

lib/java_buildpack/framework/spring_insight.rb

@@ -15,7 +15,9 @@
 # limitations under the License.
 
 require 'java_buildpack/component/base_component'
+require 'java_buildpack/util/cache/internet_availability'
 require 'java_buildpack/framework'
+require 'java_buildpack/util/dash_case'
 require 'tmpdir'
 require 'fileutils'
 require 'uri'
@@ -41,7 +43,9 @@ def detect
 
       # (see JavaBuildpack::Component::BaseComponent#compile)
       def compile
-        download(@version, @uri.chomp('/') + AGENT_DOWNLOAD_URI_SUFFIX) { |file| expand file } # TODO: AGENT_DOWNLOAD_URI_SUFFIX To be removed once the full path is included in VCAP_SERVICES see issue 58873498
+        JavaBuildpack::Util::Cache::InternetAvailability.instance.available(true, 'The Spring Insight download location is always accessible') do
+          download(@version, @uri.chomp('/') + AGENT_DOWNLOAD_URI_SUFFIX) { |file| expand file } # TODO: AGENT_DOWNLOAD_URI_SUFFIX To be removed once the full path is included in VCAP_SERVICES see issue 58873498
+        end
       end
 
       # (see JavaBuildpack::Component::BaseComponent#release)

lib/java_buildpack/util/cache/internet_availability.rb

@@ -47,10 +47,20 @@ def available?
         #
         # @param [Boolean] available whether the internet is available
         # @param [String, nil] message an optional message to be printed when the availability is set
+        # @yields an environment with internet availability temporarily overridden if block given
         def available(available, message = nil)
           @monitor.synchronize do
-            @available = available
-            @logger.warn { "Internet availability set to #{available}: #{message}" } if message
+            if block_given?
+              preserve_availability do
+                @available = available
+                @logger.warn { "Internet availability temporarily set to #{available}: #{message}" } if message
+
+                yield
+              end
+            else
+              @available = available
+              @logger.warn { "Internet availability set to #{available}: #{message}" } if message
+            end
           end
         end
 
@@ -60,6 +70,15 @@ def remote_downloads?
           JavaBuildpack::Util::ConfigurationUtils.load('cache')['remote_downloads'] != 'disabled'
         end
 
+        def preserve_availability
+          previous = @available
+          begin
+            yield
+          ensure
+            @available = previous
+          end
+        end
+
       end
 
     end

spec/java_buildpack/framework/spring_insight_spec.rb

@@ -17,10 +17,12 @@
 require 'spec_helper'
 require 'component_helper'
 require 'fileutils'
+require 'internet_availability_helper'
 require 'java_buildpack/framework/spring_insight'
 
 describe JavaBuildpack::Framework::SpringInsight do
   include_context 'component_helper'
+  include_context 'internet_availability_helper'
 
   it 'should not detect without spring-insight-n/a service' do
     expect(component.detect).to be_nil
@@ -51,6 +53,13 @@
       expect(sandbox + 'insight/conf/insight.properties').to exist
     end
 
+    it 'should guarantee that internet access is available when downloading' do
+      expect_any_instance_of(JavaBuildpack::Util::Cache::InternetAvailability)
+      .to receive(:available).with(true, 'The Spring Insight download location is always accessible')
+
+      component.compile
+    end
+
     it 'should update JAVA_OPTS',
        app_fixture: 'framework_spring_insight' do
 

spec/java_buildpack/util/cache/internet_availability_spec.rb

@@ -55,4 +55,22 @@
     expect(log_contents).to match(/Internet availability set to false: test message/)
   end
 
+  it 'should temporarily set internet unavailable' do
+    expect(described_class.instance.available?).to be
+
+    described_class.instance.available(false) { expect(described_class.instance.available?).not_to be }
+
+    expect(described_class.instance.available?).to be
+  end
+
+  it 'should temporarily set internet available',
+     :disable_internet do
+
+    expect(described_class.instance.available?).not_to be
+
+    described_class.instance.available(true) { expect(described_class.instance.available?).to be }
+
+    expect(described_class.instance.available?).not_to be
+  end
+
 end