// Do not edit this file (e.g. go instead to src/main/asciidoc)
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.
== Features
=== Spring Cloud Config Server
* HTTP, resource-based API for external configuration (name-value pairs, or equivalent YAML content)
* Encrypt and decrypt property values (symmetric or asymmetric)
* Embeddable easily in a Spring Boot application using `@EnableConfigServer`
=== Spring Cloud Config Client
Specifically for Spring applications:
* Bind to the Config Server and initialize Spring `Environment` with remote property sources
* Encrypt and decrypt property values (symmetric or asymmetric)
* `@RefreshScope` for Spring `@Beans` that want to be re-initialized when configuration changes
* Management endpoints:
** `/env` for updating `Environment` 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 the `Lifecycle` methods (`stop()` and `start()` on the `ApplicationContext`)
* 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)
== Quick Start
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.platform.config.server.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 service has resources in the form:
----
/{application}/{profile}[/{label}]
----
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").
=== Client Side Usage
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-starters`) for Maven users and a
Spring IO version management properties file for Gradle and Spring CLI
users. Example Maven configuration:
[source,xml,indent=0]
.pom.xml
----
<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-starters</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).
=== Sample Application
There is a sample application
https://github.com/spring-cloud/spring-cloud-config/tree/master/spring-cloud-config-sample[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.platform.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.