Migrate dynatrace integration to LD_PRELOAD

Migrate the dnytrace integration to use the LD_PRELOAD method as
used within other buildpacks.

* Set LD_PRELOAD environment variable instead of java options
* adapt tests and test fixtures

Author: jm-dt

lib/java_buildpack/framework/dynatrace_one_agent.rb

@@ -68,8 +68,8 @@ def release
 
         manifest = agent_manifest
 
-        @droplet.java_opts.add_agentpath(agent_path(manifest))
-        @droplet.java_opts.add_preformatted_options('-Xshare:off')
+        environment_variables = @droplet.environment_variables
+        environment_variables.add_environment_variable(LD_PRELOAD, agent_path(manifest))
 
         dynatrace_environment_variables(manifest)
       end
@@ -99,6 +99,8 @@ def supports?
 
       DT_NETWORK_ZONE = 'DT_NETWORK_ZONE'
 
+      LD_PRELOAD = 'LD_PRELOAD'
+
       ENVIRONMENTID = 'environmentid'
 
       FILTER = /dynatrace/.freeze
@@ -126,8 +128,8 @@ def agent_manifest
 
       def agent_path(manifest)
         technologies  = manifest['technologies']
-        java_binaries = technologies['java']['linux-x86-64']
-        loader        = java_binaries.find { |bin| bin['binarytype'] == 'loader' }
+        java_binaries = technologies['process']['linux-x86-64']
+        loader        = java_binaries.find { |bin| bin['binarytype'] == 'primary' }
         @droplet.sandbox + loader['path']
       end
 

spec/fixtures/framework_dynatrace_one_agent/.java-buildpack/dynatrace_one_agent/manifest.json

@@ -1,10 +1,10 @@
 {
   "technologies" : {
-    "java" : {
+    "process" : {
       "linux-x86-64" : [
           {
-            "path": "agent/lib64/liboneagentloader.so",
-            "binarytype" : "loader"
+            "path": "agent/lib64/liboneagentproc.so",
+            "binarytype" : "primary"
           }
       ]
     }

spec/fixtures/stub-dynatrace-one-agent.zip

@@ -50,18 +50,17 @@
 
       component.compile
 
-      expect(sandbox + 'agent/lib64/liboneagentloader.so').to exist
+      expect(sandbox + 'agent/lib64/liboneagentproc.so').to exist
       expect(sandbox + 'manifest.json').to exist
     end
 
-    it 'updates JAVA_OPTS with agent loader and share set to off',
+    it 'sets LD_PRELOAD with liboneagentproc',
        app_fixture: 'framework_dynatrace_one_agent' do
 
       component.release
 
-      expect(java_opts).to include('-agentpath:$PWD/.java-buildpack/dynatrace_one_agent/agent/lib64/' \
-                                   'liboneagentloader.so')
-      expect(java_opts).to include('-Xshare:off')
+      expect(environment_variables).to include('LD_PRELOAD=$PWD/.java-buildpack/dynatrace_one_agent/agent/lib64/' \
+                                              'liboneagentproc.so')
     end
 
     it 'updates environment variables',
@@ -112,7 +111,7 @@
 
         component.compile
 
-        expect(sandbox + 'agent/lib64/liboneagentloader.so').to exist
+        expect(sandbox + 'agent/lib64/liboneagentproc.so').to exist
         expect(sandbox + 'manifest.json').to exist
       end
     end