197 lines
11 KiB
Plaintext
197 lines
11 KiB
Plaintext
// Do not edit this file (e.g. go instead to docs/src/main/asciidoc)
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= Spring Cloud Bus
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Spring Cloud Bus links nodes of a distributed system with a lightweight message broker. This can then be used to broadcast state changes (e.g. configuration changes) or other management instructions. A key idea is that the Bus is like a distributed Actuator for a Spring Boot application that is scaled out, but it can also be used as a communication channel between apps. The only implementation currently is with an AMQP broker as the transport, but the same basic feature set (and some more depending on the transport) is on the roadmap for other transports.
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== Quick Start
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Spring Cloud Bus works by adding Spring Boot autconfiguration if it detects itself on the classpath. All you need to do to enable the bus is to add `spring-cloud-starter-bus-amqp` to your dependency management and Spring Cloud takes care of the rest. Make sure RabbitMQ is available and configured to provide a `ConnectionFactory`: running on localhost you shouldn't have to do anything, but if you are running remotely use Spring Cloud Connectors, or Spring Boot conventions to define the broker credentials, e.g.
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.application.yml
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----
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spring:
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rabbitmq:
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host: mybroker.com
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port: 5672
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username: user
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password: secret
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----
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The bus currently supports sending messages to all nodes listening or all nodes for a particular service (as defined by Eureka). More selector criteria will be added in the future (ie. only service X nodes in data center Y, etc...). The http endpoints are under the `/bus/*` actuator namespace. There are currently two implemented. The first, `/bus/env`, sends key/values pairs to update each nodes Spring Environment. The second, `/bus/refresh`, will reload each application's configuration, just as if they had all been pinged on their `/refresh` endpoint.
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== Building
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:jdkversion: 1.7
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=== Basic Compile and Test
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To build the source you will need to install JDK {jdkversion}.
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Spring Cloud uses Maven for most build-related activities, and you
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should be able to get off the ground quite quickly by cloning the
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project you are interested in and typing
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----
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$ ./mvnw install
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----
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NOTE: You can also install Maven (>=3.3.3) yourself and run the `mvn` command
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in place of `./mvnw` in the examples below. If you do that you also
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might need to add `-P spring` if your local Maven settings do not
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contain repository declarations for spring pre-release artifacts.
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NOTE: Be aware that you might need to increase the amount of memory
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available to Maven by setting a `MAVEN_OPTS` environment variable with
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a value like `-Xmx512m -XX:MaxPermSize=128m`. We try to cover this in
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the `.mvn` configuration, so if you find you have to do it to make a
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build succeed, please raise a ticket to get the settings added to
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source control.
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For hints on how to build the project look in `.travis.yml` if there
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is one. There should be a "script" and maybe "install" command. Also
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look at the "services" section to see if any services need to be
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running locally (e.g. mongo or rabbit). Ignore the git-related bits
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that you might find in "before_install" since they're related to setting git
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credentials and you already have those.
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The projects that require middleware generally include a
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`docker-compose.yml`, so consider using
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http://compose.docker.io/[Docker Compose] to run the middeware servers
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in Docker containers. See the README in the
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https://github.com/spring-cloud-samples/scripts[scripts demo
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repository] for specific instructions about the common cases of mongo,
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rabbit and redis.
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NOTE: If all else fails, build with the command from `.travis.yml` (usually
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`./mvnw install`).
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=== Documentation
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The spring-cloud-build module has a "docs" profile, and if you switch
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that on it will try to build asciidoc sources from
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`src/main/asciidoc`. As part of that process it will look for a
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`README.adoc` and process it by loading all the includes, but not
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parsing or rendering it, just copying it to `${main.basedir}`
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(defaults to `${basedir}`, i.e. the root of the project). If there are
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any changes in the README it will then show up after a Maven build as
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a modified file in the correct place. Just commit it and push the change.
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=== Working with the code
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If you don't have an IDE preference we would recommend that you use
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http://www.springsource.com/developer/sts[Spring Tools Suite] or
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http://eclipse.org[Eclipse] when working with the code. We use the
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http://eclipse.org/m2e/[m2eclipe] eclipse plugin for maven support. Other IDEs and tools
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should also work without issue.
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==== Importing into eclipse with m2eclipse
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We recommend the http://eclipse.org/m2e/[m2eclipe] eclipse plugin when working with
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eclipse. If you don't already have m2eclipse installed it is available from the "eclipse
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marketplace".
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Unfortunately m2e does not yet support Maven 3.3, so once the projects
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are imported into Eclipse you will also need to tell m2eclipse to use
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the `.settings.xml` file for the projects. If you do not do this you
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may see many different errors related to the POMs in the
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projects. Open your Eclipse preferences, expand the Maven
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preferences, and select User Settings. In the User Settings field
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click Browse and navigate to the Spring Cloud project you imported
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selecting the `.settings.xml` file in that project. Click Apply and
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then OK to save the preference changes.
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NOTE: Alternatively you can copy the repository settings from https://github.com/spring-cloud/spring-cloud-build/blob/master/.settings.xml[`.settings.xml`] into your own `~/.m2/settings.xml`.
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==== Importing into eclipse without m2eclipse
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If you prefer not to use m2eclipse you can generate eclipse project metadata using the
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following command:
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[indent=0]
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----
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$ ./mvnw eclipse:eclipse
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----
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The generated eclipse projects can be imported by selecting `import existing projects`
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from the `file` menu.
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==== Adding Project Lombok Agent
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Spring Cloud uses http://projectlombok.org/features/index.html[Project Lombok]
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to generate getters and setters etc. Compiling from the command line this
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shouldn't cause any problems, but in an IDE you need to add an agent
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to the JVM. Full instructions can be found in the Lombok website. The
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sign that you need to do this is a lot of compiler errors to do with
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missing methods and fields, e.g.
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[indent=0]
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----
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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
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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
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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
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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
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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
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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
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----
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==== Importing into Intellij
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Spring Cloud projects use annotation processing, particularly Lombok, which requires configuration
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or you will encounter compile problems. It also needs a specific version of maven and a profile
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enabled. Intellij 14.1+ requires some configuration to ensure these are setup properly.
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1. Click Preferences, Plugins. *Ensure Lombok is installed*
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2. Click New, Project from Existing Sources, choose your spring-cloud-sleuth directory
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3. Choose Maven, and select Environment Settings. *Ensure you are using Maven 3.3.3*
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4. In the next screen, *Select the profile `spring`* click Next until Finish.
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5. Click Preferences, "Build, Execution, Deployment", Compiler, Annotation Processors. *Click Enable Annotation Processing*
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6. Click Build, Rebuild Project, and you are ready to go!
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==== Importing into other IDEs
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Maven is well supported by most Java IDEs. Refer to you vendor documentation.
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== Contributing
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Spring Cloud is released under the non-restrictive Apache 2.0 license,
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and follows a very standard Github development process, using Github
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tracker for issues and merging pull requests into master. If you want
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to contribute even something trivial please do not hesitate, but
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follow the guidelines below.
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=== Sign the Contributor License Agreement
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Before we accept a non-trivial patch or pull request we will need you to sign the
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https://support.springsource.com/spring_committer_signup[contributor's agreement].
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Signing the contributor's agreement does not grant anyone commit rights to the main
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repository, but it does mean that we can accept your contributions, and you will get an
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author credit if we do. Active contributors might be asked to join the core team, and
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given the ability to merge pull requests.
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=== Code of Conduct
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This project adheres to the Contributor Covenant https://github.com/spring-cloud/spring-cloud-build/blob/master/docs/src/main/asciidoc/code-of-conduct.adoc[code of
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conduct]. By participating, you are expected to uphold this code. Please report
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unacceptable behavior to spring-code-of-conduct@pivotal.io.
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=== Code Conventions and Housekeeping
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None of these is essential for a pull request, but they will all help. They can also be
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added after the original pull request but before a merge.
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* Use the Spring Framework code format conventions. If you use Eclipse
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you can import formatter settings using the
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`eclipse-code-formatter.xml` file from the
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https://raw.githubusercontent.com/spring-cloud/spring-cloud-build/master/spring-cloud-dependencies-parent/eclipse-code-formatter.xml[Spring
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Cloud Build] project. If using IntelliJ, you can use the
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http://plugins.jetbrains.com/plugin/6546[Eclipse Code Formatter
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Plugin] to import the same file.
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* Make sure all new `.java` files to have a simple Javadoc class comment with at least an
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`@author` tag identifying you, and preferably at least a paragraph on what the class is
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for.
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* Add the ASF license header comment to all new `.java` files (copy from existing files
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in the project)
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* Add yourself as an `@author` to the .java files that you modify substantially (more
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than cosmetic changes).
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* Add some Javadocs and, if you change the namespace, some XSD doc elements.
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* A few unit tests would help a lot as well -- someone has to do it.
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* If no-one else is using your branch, please rebase it against the current master (or
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other target branch in the main project).
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* When writing a commit message please follow http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html[these conventions],
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if you are fixing an existing issue please add `Fixes gh-XXXX` at the end of the commit
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message (where XXXX is the issue number). |