Add README.md

README.md

+Spring Boot - Maven 3 - CentOS Docker image
+========================================
+
+This repository contains the sources and
+[Dockerfile](https://github.com/codecentric/springboot-maven3-centos/blob/master/Dockerfile)
+of the base image for deploying Spring Boot applications as reproducible Docker
+images. The resulting images can be run either by [Docker](http://docker.io)
+or using [STI](https://github.com/openshift/source-to-image).
+
+This image is heavily inspired by the awesome [openshift/ruby-20-centos](https://github.com/openshift/ruby-20-centos/)
+builder image.
+
+Installation
+---------------
+
+_TODO_ Publish Image to Docker Hub
+
+Repository organization
+------------------------
+
+* **`.sti/bin/`**
+
+  This folder contains scripts that are run by [STI](https://github.com/openshift/source-to-image):
+
+  *   **assemble**
+
+      Is used to restore the build artifacts from the previous built (in case of
+      'incremental build'), to install the sources into location from where the
+      application will be run and prepare the application for deployment (eg.
+      using maven to build the application etc..)
+
+  *   **run**
+
+      This script is responsible for running a Spring Boot fat jar using `java -jar`.
+      The image exposes port 8080, so it expects application to listen on port
+      8080 for incoming request.
+
+  *   **save-artifacts**
+
+      In order to do an *incremental build* (iow. re-use the build artifacts
+      from an already built image in a new image), this script is responsible for
+      archiving those. In this image, this script will archive the
+      `/opt/java/.m2` directory.
+
+Environment variables
+---------------------
+
+*  **APP_ROOT** (default: '.')
+
+    This variable specifies a relative location to your application inside the
+    application GIT repository. In case your application is located in a
+    sub-folder, you can set this variable to a *./myapplication*.
+
+*  **STI_SCRIPTS_URL** (default: '[.sti/bin](https://raw.githubusercontent.com/codecentric/springboot-maven3-centos/master/.sti/bin)')
+
+    This variable specifies the location of directory, where *assemble*, *run* and
+    *save-artifacts* scripts are downloaded/copied from. By default the scripts
+    in this repository will be used, but users can provide an alternative
+    location and run their own scripts.
+
+Contributing
+------------
+
+In order to test your changes to this STI image or to the STI scripts, you can
+use the `test/run` script. Before that, you have to build the 'candidate' image:
+
+```
+$ docker build -t openshift/ruby-20-centos-candidate .
+```
+
+After that you can execute `./test/run`. You can also use `make test` to
+automate this.
+
+Usage
+---------------------
+
+**Building the [spring-boot-example](https://github.com/codecentric/spring-boot-example) Spring Boot application..**
+
+1. **using standalone [STI](https://github.com/openshift/source-to-image) and running the resulting image by [Docker](http://docker.io):**
+
+```
+$ sti build git://github.com/codecentric/spring-boot-example codecentric/springboot-maven3-centos spring-boot-app
+$ docker run -p 8080:8080 spring-boot-app
+```
+
+**Accessing the application:**
+```
+$ curl 127.0.0.1:8080
+```
+
+Copyright
+--------------------
+
+Released under the Apache License 2.0. See the [LICENSE](https://github.com/codecentric/springboot-maven3-centos/blob/master/LICENSE) file.