Spring Cloud Config provides server and client-side support for externalized configuration in a distributed system. With the Config Server you have a central place to manage external properties for applications across all environments. The concepts on both client and server map identically to the Spring Environment and PropertySource abstractions, so they fit very well with Spring applications, but can be used with any application running in any language. As an application moves through the deployment pipeline from dev to test and into production you can manage the configuration between those environments and be certain that applications have everything they need to run when they migrate. The default implementation of the server storage backend uses git so it easily supports labelled versions of configuration environments, as well as being accessible to a wide range of tooling for managing the content. It is easy to add alternative implementations and plug them in with Spring configuration.
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HTTP, resource-based API for external configuration (name-value pairs, or equivalent YAML content)
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Encrypt and decrypt property values (symmetric or asymmetric)
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Embeddable easily in a Spring Boot application using
@EnableConfigServer
Specifically for Spring applications:
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Bind to the Config Server and initialize Spring
Environmentwith remote property sources -
Encrypt and decrypt property values (symmetric or asymmetric)
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@RefreshScopefor Spring@Beansthat want to be re-initialized when configuration changes -
Management endpoints:
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/envfor updatingEnvironmentand rebinding@ConfigurationPropertiesand log levels -
/refreshfor refreshing the@RefreshScopebeans -
/restartfor restarting the Spring context (disabled by default) -
/pauseand/resumefor calling theLifecyclemethods (stop()andstart()on theApplicationContext)
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Bootstrap appplication context: a parent context for the main application that can be trained to do anything (by default it binds to the Config Server, and decrypts property values)
Start the server:
$ cd spring-cloud-config-server $ mvn spring-boot:run
The server is a Spring Boot application so you can build the jar file
and run that (java -jar …) or pull it down from a Maven
repository. Then try it out as a client:
$ curl localhost:8888/foo/development
{"name":"development","label":"master","propertySources":[
{"name":"https://github.com/scratches/config-repo/foo-development.properties","source":{"bar":"spam"}},
{"name":"https://github.com/scratches/config-repo/foo.properties","source":{"foo":"bar"}}
]}
The default strategy for locating property sources is to clone a git
repository (at "spring.cloud.config.server.git.uri") and use it to
initialize a mini SpringApplication. The mini-application’s
Environment is used to enumerate property sources and publish them
via a JSON endpoint.
The HTTP service has resources in the form:
/{application}/{profile}[/{label}]
/{application}-{profile}.yml
/{label}/{application}-{profile}.yml
/{application}-{profile}.properties
/{label}/{application}-{profile}.properties
where the "application" is injected as the "spring.config.name" in the
SpringApplication (i.e. what is normally "application" in a regular
Spring Boot app), "profile" is an active profile (or comma-separated
list of properties), and "label" is an optional git label (defaults to
"master".)
The YAML and properties forms are coalesced into a single map, even if the origin of the values (reflected in the "propertySources" of the "standard" form) has multiple sources.
Spring Cloud Config Server pulls configuration for remote clients from a git repository (which must be provided):
spring:
cloud:
config:
server:
git:
uri: https://github.com/spring-cloud-samples/config-repo
To use these features in an application, just build it as a Spring
Boot application that depends on spring-cloud-config-client (e.g. see
the test cases for the config-client, or the sample app). The most
convenient way to add the dependency is via a Spring Boot starter
org.springframework.cloud:spring-cloud-starter. There is also a
parent pom and BOM (spring-cloud-starter-parent) for Maven users and a
Spring IO version management properties file for Gradle and Spring CLI
users. Example Maven configuration:
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.1.7.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-parent</artifactId>
<version>1.0.0.BUILD-SNAPSHOT</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<!-- repositories also needed for snapshots and milestones -->Then you can create a standard Spring Boot application, like this simple HTTP server:
@Configuration
@EnableAutoConfiguration
@RestController
public class Application {
@RequestMapping("/")
public String home() {
return "Hello World!";
}
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
When it runs it will pick up the external configuration from the
default local config server on port 8888 if it is running. To modify
the startup behaviour you can change the location of the config server
using bootstrap.properties (like application.properties but for
the bootstrap phase of an application context), e.g.
spring.cloud.config.uri: http://myconfigserver.com
The bootstrap properties will show up in the /env endpoint as a
high-priority property source, e.g.
$ curl localhost:8080/env
{
"profiles":[],
"configService:https://github.com/scratches/config-repo/bar.properties":{"foo":"bar"},
"servletContextInitParams":{},
"systemProperties":{...},
...
}
(a property source called "configService:<URL of remote repository>/<file name>" contains the property "foo" with value "bar" and is highest priority).
There is a sample application here. It is a Spring Boot application so you can run it using the usual mechanisms (for instance "mvn spring-boot:run"). When it runs it will look for the config server on "http://localhost:8888" by default, so you could run the server as well to see it all working together.
The sample has a test case where the config server is also started in the same JVM (with a different port), and the test asserts that an environment property from the git configuration repo is present. To change the location of the config server just set "spring.cloud.config.uri" in "bootstrap.yml" (or via System properties etc.).
The test case has a main() method that runs the server in the same
way (watch the logs for its port), so you can run the whole system in
one process and play with it (e.g. right click on the main in your IDE
and run it). The main() method uses target/config for the working
directory of the git repository, so you can make local changes there
and see them reflected in the running app.
$ curl localhost:8080/env/foo bar $ vi target/config/bar.properties .. change value of "foo", optionally commit $ curl localhost:8080/refresh ["foo"] $ curl localhost:8080/env/foo baz
The refresh endpoint reports that the "foo" property changed.
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
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Note
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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
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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.
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.
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.
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.
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.
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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.xmlfile from theeclipsefolder. If using IntelliJ, you can use the Eclipse Code Formatter Plugin to import the same file. -
Make sure all new
.javafiles to have a simple Javadoc class comment with at least an@authortag identifying you, and preferably at least a paragraph on what the class is for. -
Add the ASF license header comment to all new
.javafiles (copy from existing files in the project) -
Add yourself as an
@authorto the .java files that you modify substantially (more than cosmetic changes). -
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 other target branch in the main project).
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.
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".
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.
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
Spring Cloud 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.
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.
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.xmlfile 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
.javafiles to have a simple Javadoc class comment with at least an@authortag identifying you, and preferably at least a paragraph on what the class is for. -
Add the ASF license header comment to all new
.javafiles (copy from existing files in the project) -
Add yourself as an
@authorto 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-XXXXat the end of the commit message (where XXXX is the issue number).