[#104558394]Configuration for the DynaTrace agent name

The commit allows users to set a default agent name in the
configuration for DynaTrace.

Closes #234
[#104558394]

config/dyna_trace_agent.yml

@@ -17,3 +17,4 @@
 ---
 version: 6.1.0_+
 repository_root: ""
+default_agent_name:

docs/framework-dyna_trace_agent.md

@@ -66,6 +66,7 @@ The framework can be configured by modifying the [`config/dyna_trace_agent.yml`]
 | ---- | -----------
 | `repository_root` | The URL of the DynaTrace repository index ([details][repositories]).
 | `version` | The version of DynaTrace to use. This buildpack framework has been tested on 6.1.0.
+| `default_agent_name` | This is omitted by default but can be added to set the DynaTrace agent name. If it is not specified then `#{application_name}_#{profile_name}` is used, where `application_name` is defined by Cloud Foundry.
 
 ### Additional Resources
 The framework can also be configured by overlaying a set of resources on the default distribution. To do this, add files to the `resources/dyna_trace_agent` directory in the buildpack fork.

lib/java_buildpack/framework/dyna_trace_agent.rb

@@ -59,7 +59,7 @@ def agent_path
       end
 
       def agent_name
-        "#{@application.details['application_name']}_#{profile_name}"
+        @configuration['default_agent_name'] || "#{@application.details['application_name']}_#{profile_name}"
       end
 
       def architecture

spec/java_buildpack/framework/dyna_trace_agent_spec.rb

@@ -21,6 +21,10 @@
 describe JavaBuildpack::Framework::DynaTraceAgent do
   include_context 'component_helper'
 
+  let(:configuration) do
+    { 'default_agent_name' => nil }
+  end
+
   it 'does not detect without dynatrace-n/a service' do
     expect(component.detect).to be_nil
   end
@@ -45,23 +49,33 @@
 
     it 'updates JAVA_OPTS' do
       component.release
-      expect(java_opts).to include(
-        '-agentpath:$PWD/.java-buildpack/dyna_trace_agent/agent/lib64/'\
+      expect(java_opts).to include('-agentpath:$PWD/.java-buildpack/dyna_trace_agent/agent/lib64/'\
         'libdtagent.so=name=test-application-name_Monitoring,server=test-host-name')
     end
+
+    context do
+
+      let(:configuration) { { 'default_agent_name' => 'different-agent-name' } }
+
+      it 'updates JAVA_OPTS with configured agent name' do
+        component.release
+        expect(java_opts).to include('-agentpath:$PWD/.java-buildpack/dyna_trace_agent/agent/lib64/'\
+        'libdtagent.so=name=different-agent-name,server=test-host-name')
+      end
+
+    end
   end
 
   context do
     before do
       allow(services).to receive(:one_service?).with(/dynatrace/, 'server').and_return(true)
-      allow(services).to receive(:find_service).and_return('credentials' => { 'server' => 'test-host-name',
+      allow(services).to receive(:find_service).and_return('credentials' => { 'server'  => 'test-host-name',
                                                                               'profile' => 'test-profile' })
     end
 
     it 'updates JAVA_OPTS with custom profile' do
       component.release
-      expect(java_opts).to include(
-        '-agentpath:$PWD/.java-buildpack/dyna_trace_agent/agent/lib64/'\
+      expect(java_opts).to include('-agentpath:$PWD/.java-buildpack/dyna_trace_agent/agent/lib64/'\
         'libdtagent.so=name=test-application-name_test-profile,server=test-host-name')
     end