Tomcat Context Path

This change updates the Tomcat container to allow a user to configure
the context path that an application is exposed at.  Previously, the
application was always exposed at the root ('/') but this didn't work
for many applications that had hard-coded context-path assumptions. In
addition, changes to the Cloud Foundry router mean that applications
can now be routed via both a host and a context path.

[#101289516]

Author: nebhale

README.md

@@ -10,7 +10,7 @@ The `java-buildpack` is a [Cloud Foundry][] buildpack for running JVM-based appl
 To use this buildpack specify the URI of the repository when pushing an application to Cloud Foundry:
 
 ```bash
-cf push <APP-NAME> -p <ARTIFACT> -b https://github.com/cloudfoundry/java-buildpack.git
+$ cf push <APP-NAME> -p <ARTIFACT> -b https://github.com/cloudfoundry/java-buildpack.git
 ```
 
 ## Examples
@@ -29,11 +29,15 @@ The buildpack supports extension through the use of Git repository forking. The
 
 Buildpack configuration can be overridden with an environment variable matching the configuration file you wish to override minus the `.yml` extension and with a prefix of `JBP_CONFIG`. It is not possible to add new configuration properties and properties with `nil` or empty values will be ignored by the buildpack. The value of the variable should be valid inline yaml. For example, to change the default version of Java to 7 and adjust the memory heuristics apply this environment variable to the application.
 
-```cf set-env my-application JBP_CONFIG_OPEN_JDK_JRE '[jre: {version: 1.7.0_+}, memory_calculator: {memory_heuristics: {heap: 85, stack: 10}}]'```
+```bash
+$ cf set-env my-application JBP_CONFIG_OPEN_JDK_JRE 'jre: { version: 1.7.0_+ }'
+```
 
 If the key or value contains a special character such as `:` it should be escaped with double quotes. For example, to change the default repository path for the buildpack.
 
-```cf set-env my-application JBP_CONFIG_REPOSITORY '[ default_repository_root: "http://repo.example.io" ]'```
+```bash
+$ cf set-env my-application JBP_CONFIG_REPOSITORY 'default_repository_root: "http://repo.example.io"'
+```
 
 Environment variable can also be specified in the applications `manifest` file. See the [Environment Variables][] documentation for more information.
 
@@ -92,8 +96,8 @@ The buildpack can be packaged up so that it can be uploaded to Cloud Foundry usi
 The online package is a version of the buildpack that is as minimal as possible and is configured to connect to the network for all dependencies.  This package is about 50K in size.  To create the online package, run:
 
 ```bash
-bundle install
-bundle exec rake package
+$ bundle install
+$ bundle exec rake package
 ...
 Creating build/java-buildpack-cfd6b17.zip
 ```
@@ -104,8 +108,8 @@ The offline package is a version of the buildpack designed to run without access
 To pin the version of dependencies used by the buildpack to the ones currently resolvable use the `PINNED=true` argument. This will update the [`config/` directory][] to contain exact version of each dependency instead of version ranges.
 
 ```bash
-bundle install
-bundle exec rake package OFFLINE=true PINNED=true
+$ bundle install
+$ bundle exec rake package OFFLINE=true PINNED=true
 ...
 Creating build/java-buildpack-offline-cfd6b17.zip
 ```
@@ -114,8 +118,8 @@ Creating build/java-buildpack-offline-cfd6b17.zip
 Keeping track of different versions of the buildpack can be difficult.  To help with this, the rake `package` task puts a version discriminator in the name of the created package file.  The default value for this discriminator is the current Git hash (e.g. `cfd6b17`).  To change the version when creating a package, use the `VERSION=<VERSION>` argument:
 
 ```bash
-bundle install
-bundle exec rake package VERSION=2.1
+$ bundle install
+$ bundle exec rake package VERSION=2.1
 ...
 Creating build/java-buildpack-2.1.zip
 ```
@@ -124,8 +128,8 @@ Creating build/java-buildpack-2.1.zip
 To run the tests, do the following:
 
 ```bash
-bundle install
-bundle exec rake
+$ bundle install
+$ bundle exec rake
 ```
 
 [Running Cloud Foundry locally][] is useful for privately testing new features.

config/tomcat.yml

@@ -18,6 +18,7 @@
 tomcat:
   version: 8.0.+
   repository_root: ! '{default.repository.root}/tomcat'
+  context_path:
 lifecycle_support:
   version: 2.+
   repository_root: ! '{default.repository.root}/tomcat-lifecycle-support'

docs/container-tomcat.md

@@ -12,7 +12,7 @@ The Tomcat Container allows servlet 2 and 3 web applications to be run.  These a
 </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
 For general information on configuring the buildpack, refer to [Configuration and Extension][].
@@ -45,9 +45,24 @@ The container can be configured by modifying the [`config/tomcat.yml`][] file in
 | `redis_store.repository_root` | The URL of the Redis Store repository index ([details][repositories]).
 | `redis_store.timeout` | The Redis connection timeout (in milliseconds).
 | `redis_store.version` | The version of Redis Store to use. Candidate versions can be found in [this listing](http://download.pivotal.io.s3.amazonaws.com/redis-store/index.yml).
+| `tomcat.context_path` | The context path to expose the application at.
 | `tomcat.repository_root` | The URL of the Tomcat repository index ([details][repositories]).
 | `tomcat.version` | The version of Tomcat to use. Candidate versions can be found in [this listing](http://download.pivotal.io.s3.amazonaws.com/tomcat/index.yml).
 
+### Common configurations
+The version of Tomcat can be configured by setting an environment variable.
+
+```
+$ cf set-env my-application JBP_CONFIG_TOMCAT 'tomcat: { version: 7.0.+ }'
+```
+
+The context path that an application is deployed at can be configured by setting an environment variable.
+
+```
+$ cf set-env my-application JBP_CONFIG_TOMCAT 'tomcat: { context_path: /first-segement/second-segment }'
+```
+
+
 ### Additional Resources
 The container can also be configured by overlaying a set of resources on the default distribution.  To do this, add files to the `resources/tomcat` directory in the buildpack fork.  For example, to override the default `logging.properties` add your custom file to `resources/tomcat/conf/logging.properties`.
 

lib/java_buildpack/container/tomcat/tomcat_instance.rb

@@ -98,7 +98,8 @@ def expand(file)
       end
 
       def root
-        tomcat_webapps + 'ROOT'
+        context_path = (@configuration['context_path'] || 'ROOT').sub(%r{^/}, '').gsub(%r{/}, '#')
+        tomcat_webapps + context_path
       end
 
       def tomcat_datasource_jar

spec/java_buildpack/container/tomcat/tomcat_instance_spec.rb

@@ -95,6 +95,33 @@
     expect(root_webapp + '.test-file').not_to exist
   end
 
+  context do
+    let(:configuration) { { 'context_path' => '/first-segment/second-segment' } }
+
+    it 'links only the application files and directories to the ROOT webapp',
+       app_fixture:   'container_tomcat_with_index',
+       cache_fixture: 'stub-tomcat.tar.gz' do
+
+      FileUtils.touch(app_dir + '.test-file')
+
+      component.compile
+
+      root_webapp = app_dir + '.java-buildpack/tomcat/webapps/first-segment#second-segment'
+
+      web_inf = root_webapp + 'WEB-INF'
+      expect(web_inf).to exist
+      expect(web_inf).to be_symlink
+      expect(web_inf.readlink).to eq((app_dir + 'WEB-INF').relative_path_from(root_webapp))
+
+      index = root_webapp + 'index.html'
+      expect(index).to exist
+      expect(index).to be_symlink
+      expect(index.readlink).to eq((app_dir + 'index.html').relative_path_from(root_webapp))
+
+      expect(root_webapp + '.test-file').not_to exist
+    end
+  end
+
   it 'links the Tomcat datasource JAR to the ROOT webapp when that JAR is present',
      app_fixture:   'container_tomcat',
      cache_fixture: 'stub-tomcat7.tar.gz' do