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
Environment
with remote property sources -
Encrypt and decrypt property values (symmetric or asymmetric)
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@RefreshScope
for Spring@Beans
that want to be re-initialized when configuration changes -
Management endpoints:
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/env
for updatingEnvironment
and rebinding@ConfigurationProperties
and log levels -
/refresh
for refreshing the@RefreshScope
beans -
/restart
for restarting the Spring context (disabled by default) -
/pause
and/resume
for calling theLifecycle
methods (stop()
andstart()
on theApplicationContext
)
-
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Bootstrap application 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 $ ../mvnw spring-boot:run
The server is a Spring Boot application so you can run it from your
IDE instead if you prefer (the main class is
ConfigServerApplication
). Then try out 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".)
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-config
. 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>1.3.5.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Brixton.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</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:
@SpringBootApplication @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/spring-cloud-samples/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).
Note
|
the URL in the property source name is the git repository not the config server URL. |
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.
If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:
Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using).
To build the source you will need to install 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
$ ./mvnw install
Note
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You can also install Maven (>=3.3.3) yourself and run the mvn command
in place of ./mvnw in the examples below. If you do that you also
might need to add -P spring if your local Maven settings do not
contain repository declarations for spring pre-release artifacts.
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Note
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Be aware that you might need to increase the amount of memory
available to Maven by setting a MAVEN_OPTS environment variable with
a value like -Xmx512m -XX:MaxPermSize=128m . We try to cover this in
the .mvn configuration, so if you find you have to do it to make a
build succeed, please raise a ticket to get the settings added to
source control.
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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’re related to setting git
credentials and you already have those.
The projects that require middleware generally include a
docker-compose.yml
, so consider using
Docker Compose to run the middeware servers
in Docker containers. See the README in the
scripts demo
repository for specific instructions about the common cases of mongo,
rabbit and redis.
Note
|
If all else fails, build with the command from .travis.yml (usually
./mvnw install ).
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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.
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 as long as they use Maven 3.3.3 or better.
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".
Note
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Older versions of m2e do not support Maven 3.3, so once the
projects are imported into Eclipse you will also need to tell
m2eclipse to use the right profile for the projects. If you
see many different errors related to the POMs in the projects, check
that you have an up to date installation. If you can’t upgrade m2e,
add the "spring" profile to your settings.xml . Alternatively you can
copy the repository settings from the "spring" profile of the parent
pom into your settings.xml .
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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 License 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.
This project adheres to the Contributor Covenant code of conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to spring-code-of-conduct@pivotal.io.
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 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.
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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).
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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).