Add env var APPINSIGHTS_INSTRUMENTATIONKEY for compatibility

Author: mayrstefan

lib/java_buildpack/framework/azure_application_insights_agent.rb

@@ -42,6 +42,10 @@ def release
         if credentials.key?(INSTRUMENTATION_KEY)
           @droplet.java_opts.add_system_property('APPLICATION_INSIGHTS_IKEY',
                                                  credentials[INSTRUMENTATION_KEY])
+          # add environment variable for compatibility with agent version 3.x
+          # this triggers a warning message to switch to connection string
+          @droplet.environment_variables.add_environment_variable('APPINSIGHTS_INSTRUMENTATIONKEY',
+                                                                  credentials[INSTRUMENTATION_KEY])
         end
         @droplet.java_opts.add_javaagent(@droplet.sandbox + jar_name)
       end

spec/java_buildpack/framework/azure_application_insights_agent_spec.rb

@@ -72,6 +72,15 @@
       expect(java_opts).to include('-DAPPLICATION_INSIGHTS_IKEY=test-instrumentation-key')
     end
 
+    it 'updates environment variables' do
+      allow(services).to receive(:find_service)
+        .and_return('credentials' => { 'instrumentation_key' => 'test-instrumentation-key' })
+
+      component.release
+
+      expect(environment_variables).to include('APPINSIGHTS_INSTRUMENTATIONKEY=test-instrumentation-key')
+    end
+
   end
 
 end