= Contributing to Spring Boot

Spring Boot is released under the non-restrictive Apache 2.0 license. If you would like
to contribute something, or simply want to hack on the code this document should help
you get started.

== Sign the Contributor License Agreement
Before we accept a non-trivial patch or pull request we will need you to sign the
https://support.springsource.com/spring_committer_signup[contributor's agreement].
Signing the contributor's agreement does not grant anyone commit rights to the main
repository, but it does mean that we can accept your contributions, and you will get an
author credit if we do.  Active contributors might be asked to join the core team, and
given the ability to merge pull requests.

== Code Conventions and Housekeeping
None of these is essential for a pull request, but they will all help.  They can also be
added after the original pull request but before a merge.

* Use the Spring Framework code format conventions. If you use Eclipse and you follow
  the ``Importing into eclipse'' instructions below you should get project specific
  formatting automatically. You can also import formatter settings using the
  `eclipse-code-formatter.xml` file from the `eclipse` folder. If using IntelliJ, you can
  use the http://plugins.jetbrains.com/plugin/6546[Eclipse Code Formatter Plugin]
  to import the same file.
* Make sure all new `.java` files to have a simple Javadoc class comment with at least an
  `@author` tag identifying you, and preferably at least a paragraph on what the class is
  for.
* Add the ASF license header comment to all new `.java` files (copy from existing files
  in the project)
* Add yourself as an `@author` to the .java files that you modify substantially (more
  than cosmetic changes).
* Add some Javadocs and, if you change the namespace, some XSD doc elements.
* A few unit tests would help a lot as well -- someone has to do it.
* If no-one else is using your branch, please rebase it against the current master (or
  other target branch in the main project).
* When writing a commit message please follow http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html[these conventions],
  if you are fixing an existing issue please add `Fixes gh-XXXX` at the end of the commit
  message (where XXXX is the issue number).

== Working with the code
If you don't have an IDE preference we would recommend that you use
http://www.springsource.com/developer/sts[Spring Tools Suite] or
http://eclipse.org[Eclipse] when working with the code. We use the
http://eclipse.org/m2e/[m2eclipe] eclipse plugin for maven support. Other IDEs and tools
should also work without issue.

=== Building from source
To build the source you will need to install
http://maven.apache.org/run-maven/index.html[Apache Maven] v3.0.6 or above and JDK 1.7.

==== Default build
The project can be built from the root directory using the standard maven command:

[indent=0]
----
	$ mvn clean install
----

NOTE: You may need to increase the amount of memory available to Maven by setting
a `MAVEN_OPTS` environment variable with the value `-Xmx512m -XX:MaxPermSize=128m`

If you are rebuilding often, you might also want to skip the tests until you are ready
to submit a pull request:

[indent=0]
----
	$ mvn clean install -DskipTests
----

==== Full Build
Multi-module Maven builds cannot directly include maven plugins that are part of the
reactor unless they have previously been built. Unfortunately this restriction causes
some compilations for Spring Boot as we include a maven plugin and use it within the
samples. The standard build works around this restriction by launching the samples via
the `maven-invoker-plugin` so that they are not part of the reactor. This works fine
most of the time, however, sometimes it useful to run a build that includes all modules
(for example when using `maven-versions-plugin`. We use the full build on our CI servers
and during the release process.

Running a full build is a two phase process.

1) Prepare the build

Preparing the build will compile and install the `spring-boot-maven-plugin` so that it
can be referenced during the full build. It also generates a `settings.xml` file that
enables a `snapshot`, `milestone` or `release` profiles based on the version being
build. To prepare the build, from the root directory use:

[indent=0]
----
	$ mvn -P snapshot,prepare install -DskipTests
----

NOTE: You may notice that preparing the build also changes the
`spring-boot-starter-parent` POM. This is required for our release process to work
correctly.

2) Run the full build

Once the build has been prepared, you can run a full build using the following commands:

[indent=0]
----
	$ mvn -s ./settings.xml -f spring-boot-full-build -P full clean install
----

NOTE: As for the standard build, you may need to increase the amount of memory available
to Maven by setting a `MAVEN_OPTS` environment variable with the value
`-Xmx512m -XX:MaxPermSize=128m`. We generate more artifacts when running the full build
(such as Javadoc jars), so you may find the process a little slower than the standard build.

=== Importing into eclipse with m2eclipse
We recommend the http://eclipse.org/m2e/[m2eclipe] eclipse plugin when working with
eclipse. If you don't already have m2eclipse installed it is available from the "eclipse
marketplace".

Spring Boot includes project specific source formatting settings, in order to have these
work with m2eclipse, we provide an additional eclipse plugin that you can install:

* Download `org.eclipse.m2e.maveneclipse.site.zip` from
  https://github.com/philwebb/m2eclipse-maveneclipse/releases.
* Select `Install new software` from the `help` menu
* Click `Add...` to add a new repository
* Click the `Archive...` button
* Select the `org.eclipse.m2e.maveneclipse.site.zip` that you previously downloaded
* Install "Maven Integration for the maven-eclipse-plugin"

NOTE: This plugin is optional. Projects can be imported without the plugin, your code
changes just won't be automatically formatted.

With the requisite eclipse plugins installed you can select
`import existing maven projects` from the `file` menu to import the code. You will
need to import the root `spring-boot` pom and the `spring-boot-samples` pom separately.

=== Importing into eclipse without m2eclipse
If you prefer not to use m2eclipse you can generate eclipse project metadata using the
following command:

[indent=0]
----
	$ mvn eclipse:eclipse
----

The generated eclipse projects can be imported by selecting `import existing projects`
from the `file` menu.

=== Importing into other IDEs
Maven is well supported by most Java IDEs. Refer to your vendor documentation.

== Integration tests
The sample application are used as integration tests during the build (when you
`mvn install`). Due to the fact that they make use of the `spring-boot-maven-plugin`
they cannot be called directly, and so instead are launched via the
`maven-invoker-plugin`. If you encounter build failures running the integration tests,
check the `build.log` file in the appropriate sample directory.

