allow setting command line args for distzip

Adds the ability to configure the args passed to the start script when
using the distzip container format.

This lets you, for example, set:

    JBP_CONFIG_DIST_ZIP : '{ arguments: "server config.yml" }'

to add "server config.yml" as arguments to the start script. It is
analogous to JBP_CONFIG_JAVA_MAIN.

[resolves #721][resolves #811]

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

Author: chrisfarms

config/dist_zip.yml

@@ -0,0 +1,18 @@
+# Cloud Foundry Java Buildpack
+# Copyright 2013-2020 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Configuration for the DistZip container
+---
+arguments:

config/dist_zip_like.yml

@@ -0,0 +1,18 @@
+# Cloud Foundry Java Buildpack
+# Copyright 2013-2020 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Configuration for the DistZip container
+---
+arguments:

docs/container-dist_zip.md

@@ -16,11 +16,18 @@ The Dist Zip Container allows applications packaged in [`distZip`-style][] to be
 </table>
 Tags are printed to standard output by the buildpack detect script
 
-If the application uses Spring, [Spring profiles][] can be specified by setting the [`SPRING_PROFILES_ACTIVE`][] environment variable. This is automatically detected and used by Spring. The Spring Auto-reconfiguration Framework will specify the `cloud` profile in addition to any others. 
+If the application uses Spring, [Spring profiles][] can be specified by setting the [`SPRING_PROFILES_ACTIVE`][] environment variable. This is automatically detected and used by Spring. The Spring Auto-reconfiguration Framework will specify the `cloud` profile in addition to any others.
 
 ## Configuration
-The Dist Zip Container cannot be configured.
+For general information on configuring the buildpack, including how to specify configuration values through environment variables, refer to [Configuration and Extension][].
 
+The container can be configured by modifying the `config/dist_zip.yml` file in the buildpack fork.
+
+| Name | Description
+| ---- | -----------
+| `arguments` | Optional command line arguments to be passed to the start script. The arguments are specified as a single YAML scalar in plain style or enclosed in single or double quotes.
+
+[Configuration and Extension]: ../README.md#configuration-and-extension
 [`distZip`-style]: http://www.gradle.org/docs/current/userguide/application_plugin.html
 [Spring profiles]:http://blog.springsource.com/2011/02/14/spring-3-1-m1-introducing-profile/
 [`SPRING_PROFILES_ACTIVE`]: http://static.springsource.org/spring/docs/3.1.x/javadoc-api/org/springframework/core/env/AbstractEnvironment.html#ACTIVE_PROFILES_PROPERTY_NAME

lib/java_buildpack/container/dist_zip_like.rb

@@ -47,7 +47,8 @@ def release
           @droplet.environment_variables.as_env_vars,
           @droplet.java_home.as_env_var,
           'exec',
-          qualify_path(start_script(root), @droplet.root)
+          qualify_path(start_script(root), @droplet.root),
+          arguments
         ].flatten.compact.join(' ')
       end
 
@@ -76,11 +77,17 @@ def supports?
 
       private
 
+      ARGUMENTS_PROPERTY = 'arguments'
+
       PATTERN_APP_CLASSPATH = /^declare -r app_classpath=\"(.*)\"$/.freeze
 
       PATTERN_CLASSPATH = /^CLASSPATH=(.*)$/.freeze
 
-      private_constant :PATTERN_APP_CLASSPATH, :PATTERN_CLASSPATH
+      private_constant :ARGUMENTS_PROPERTY, :PATTERN_APP_CLASSPATH, :PATTERN_CLASSPATH
+
+      def arguments
+        @configuration[ARGUMENTS_PROPERTY]
+      end
 
       def augment_app_classpath(content)
         additional_classpath = (@droplet.additional_libraries + @droplet.root_libraries).sort.map do |library|

spec/java_buildpack/container/dist_zip_like_spec.rb

@@ -58,4 +58,14 @@
                                     '$PWD/bin/application')
   end
 
+  context do
+    let(:configuration) { { 'arguments' => 'some arguments' } }
+
+    it 'returns command line arguments when they are specified',
+       app_fixture: 'container_dist_zip' do
+
+      expect(component.release).to end_with('some arguments')
+    end
+  end
+
 end

spec/java_buildpack/container/dist_zip_spec.rb

@@ -52,4 +52,14 @@
     expect(component.detect).to be_nil
   end
 
+  context do
+    let(:configuration) { { 'arguments' => 'some arguments' } }
+
+    it 'returns command line arguments when they are specified',
+       app_fixture: 'container_dist_zip' do
+
+      expect(component.release).to end_with('some arguments')
+    end
+  end
+
 end