This project provides Zookeeper integrations for Spring Boot apps through autoconfiguration and binding to the Spring Environment and other Spring programming model idioms. With a few simple annotations you can quickly enable and configure the common patterns inside your application and build large distributed systems with Zookeeper based components. The patterns provided include Service Discovery and Configuration. Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon), Circuit Breaker (Hystrix) are provided by integration with Spring Cloud Netflix.

Zookeeper overview

"ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services."

See the Zookeeper site for more information. Spring Cloud Zookeeper also builds on the Apache Curator project which started life at Netflix.

Spring Cloud Zookeeper Features

• Spring Cloud DiscoveryClient implementation

  • supports Ribbon and Zuul

• Zookeeper based PropertySource loaded during the 'bootstrap' phase.

Running the sample

1. Install zookeeper (On a mac with homebrew brew install zookeeper).

2. Start zookeeper.

3. Verify zookeeper is running.

4. Run mvn --settings .settings.xml package this will bring in the required spring cloud maven repositories and build

5. Run java -jar spring-cloud-zookeeper-sample/target/spring-cloud-zookeeper-sample-1.0.0.BUILD-SNAPSHOT.jar

6. Visit http://localhost:8080, verify that {"serviceId":"testZookeeperApp","host":"<yourhost>","port":8080} results

7. run java -jar spring-cloud-zookeeper-sample/target/spring-cloud-zookeeper-sample-1.0.0.BUILD-SNAPSHOT.jar --server.port=8081

8. visit http://localhost:8080 again, verify that {"serviceId":"testZookeeperApp","host":"<yourhost>","port":8081} eventually shows up in the results in a round robbin fashion (may take a minute or so).

Building

Basic Compile and Test

To build the source you will need to install Apache Maven v3.0.6 or above and JDK 1.7.

Spring Cloud uses Maven for most build-related activities, and you should be able to get off the ground quite quickly by cloning the project you are interested in and typing

$ mvn install -s .settings.xml

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

The .settings.xml is only required the first time (or after updates to dependencies). It is there to provide repository declarations so that those do not need to be hard coded in the project poms.

For hints on how to build the project look in .travis.yml if there is one. There should be a "script" and maybe "install" command. Also look at the "services" section to see if any services need to be running locally (e.g. mongo or rabbit). Ignore the git-related bits that you might find in "before_install" since they will be able git credentials and you already have those.

If you need mongo, rabbit or redis, see the README in the scripts demo repository for instructions. For example consider using the "fig.yml" with Fig to run them in Docker containers.

Documentation

The spring-cloud-build module has a "docs" profile, and if you switch that on it will try to build asciidoc sources from src/main/asciidoc. As part of that process it will look for a README.adoc and process it by loading all the includes, but not parsing or rendering it, just copying it to ${main.basedir} (defaults to ${basedir}, i.e. the root of the project). If there are any changes in the README it will then show up after a Maven build as a modified file in the correct place. Just commit it and push the change.

Working with the code

If you don’t have an IDE preference we would recommend that you use Spring Tools Suite or Eclipse when working with the code. We use the m2eclipe eclipse plugin for maven support. Other IDEs and tools should also work without issue.

Importing into eclipse with m2eclipse

We recommend the m2eclipe eclipse plugin when working with eclipse. If you don’t already have m2eclipse installed it is available from the "eclipse marketplace".

Once the projects are imported into Eclipse you will also need to tell m2eclipse to use the .settings.xml file for the projects. If you do not do this you may see errors many different errors related to the POMs in the projects. Open your Eclipse preferences, expand the Maven preferences, and select User Settings. In the User Settings field click Browse and navigate to the Spring Cloud project you imported selecting the .settings.xml file in that project. Click Apply and then OK to save the preference changes.

Importing into eclipse without m2eclipse

If you prefer not to use m2eclipse you can generate eclipse project metadata using the following command:

$ mvn eclipse:eclipse

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

Adding Project Lombok Agent

Spring Cloud uses [Project Lombok](http://projectlombok.org/features/index.html) to generate getters and setters etc. Compiling from the command line this shouldn’t cause any problems, but in an IDE you need to add an agent to the JVM. Full instructions can be found in the Lombok website. The sign that you need to do this is a lot of compiler errors to do with missing methods and fields, e.g.

The method getInitialStatus() is undefined for the type EurekaInstanceConfigBean    EurekaDiscoveryClientConfiguration.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka   line 120    Java Problem
The method getInitialStatus() is undefined for the type EurekaInstanceConfigBean    EurekaDiscoveryClientConfiguration.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka   line 121    Java Problem
The method setNonSecurePort(int) is undefined for the type EurekaInstanceConfigBean EurekaDiscoveryClientConfiguration.java /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka   line 112    Java Problem
The type EurekaInstanceConfigBean.IdentifyingDataCenterInfo must implement the inherited abstract method DataCenterInfo.getName()   EurekaInstanceConfigBean.java   /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/eureka   line 131    Java Problem
The method getId() is undefined for the type ProxyRouteLocator.ProxyRouteSpec   PreDecorationFilter.java    /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/pre line 60 Java Problem
The method getLocation() is undefined for the type ProxyRouteLocator.ProxyRouteSpec PreDecorationFilter.java    /spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/pre line 55 Java Problem

Importing into other IDEs

Maven is well supported by most Java IDEs. Refer to you vendor documentation.

Contributing

Spring Cloud is released under the non-restrictive Apache 2.0 license, and follows a very standard Github development process, using Github tracker for issues and merging pull requests into master. If you want to contribute even something trivial please do not hesitate, but follow the guidelines below.

Sign the Contributor License Agreement

Before we accept a non-trivial patch or pull request we will need you to sign the 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 you can import formatter settings using the eclipse-code-formatter.xml file from the Spring Cloud Build project. If using IntelliJ, you can use the 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 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).