Config Server

Scalability Cloud Native Cloud Foundry

Try Cloud Foundry - Config Server

Nat Geo Photography‏

Wang Tiven October 31, 2017

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Creating an Instance
Config Server Client
- Writing Client Applications
- Service Detection
  - Spring Cloud® Connectors
  - Spring Cloud Config Client
Trying It Out

Cloud Foundry 的 Config Server 是使用了 Spring Cloud Config 开源产品。

创建 Config Server 实例可以通过 CF CLI ，也可以通过CloudFoundry vendor UI。我们推荐使用 CLI。

Creating an Instance

$ cf marketplace
Getting services from marketplace in org tiven.wang / space development as i.tiven.wang@gmail.com...
OK

service                       plans                                                                                description
...
p-circuit-breaker-dashboard   standard                                                                             Circuit Breaker Dashboard for Spring Cloud Applications
p-config-server               standard                                                                             Config Server for Spring Cloud Applications
p-service-registry            standard                                                                             Service Registry for Spring Cloud Applications
pubnub                        free                                                                                 Build Realtime Apps that Scale
...

* These service plans have an associated cost. Creating a service instance will incur this cost.

TIP:  Use 'cf marketplace -s SERVICE' to view descriptions of individual plans of a given service.

$ cf marketplace -s p-config-server
Getting service plan information for service p-config-server as i.tiven.wang@gmail.com...
OK

service plan   description     free or paid
standard       Standard Plan   free

假设存放配置的Git库地址是 https://github.com/spring-cloud-samples/config-repo; Config Server 还可以单独为某个指定配置库例如：为以 cook 开头的应用指定配置库 https://github.com/spring-cloud-services-samples/cook-config; count是说明为此 Config Server 提供几个实例。

$ cf create-service -c '{"git": { "uri": "https://github.com/spring-cloud-samples/config-repo", "repos": { "cook": { "pattern": "cook*", "uri": "https://github.com/spring-cloud-services-samples/cook-config" } } }, "count": 3 }' p-config-server standard config-server

FAILED
Invalid configuration provided for -c flag. Please provide a valid JSON object or path to a file containing a valid JSON object.

按理应该成功创建的，但是这里告诉我们配置参数的json格式不对，那么可以换用文件路径配置。

$ cf create-service p-config-server standard config-server -c ./config-server.json
Creating service instance config-server in org tiven.wang / space development as i.tiven.wang@gmail.com...
OK

Create in progress. Use 'cf services' or 'cf service config-server' to check operation status.

创建成功后可以在 Pivotal 控制台打开 Config server 服务的管理界面，可以看到简单的配置信息。

Config Server Client

这里我们依旧使用 Spring Boot 开发应用程序。 Refer to the “Cook” sample application to follow along with the code in this topic.

Writing Client Applications

使用 Spring Boot application 作为 Config Server 实例的客户端应用程序的话，先要把 maven 依赖包加进来。为了方便起见，Spring 提供了一个 starter BOM 包专门提供 Config client 所需依赖 spring-cloud-services-starter-config-client. config server 属于 spring-cloud-services 的一部分，所以可以统一设置依赖管理。想要使用 Spring Cloud Services service instances，你的客户端应用必须添加 BOMs spring-cloud-services-dependencies 和 spring-cloud-dependencies. 关于她们之间并且和 Spring Boot 之间的版本兼容请详细参考 Client Dependencies

<dependencyManagement>
  <dependencies>
     <dependency>
         <groupId>io.pivotal.spring.cloud</groupId>
         <artifactId>spring-cloud-services-dependencies</artifactId>
         <version>1.5.0.RELEASE</version>
         <type>pom</type>
         <scope>import</scope>
     </dependency>
     <dependency>
         <groupId>org.springframework.cloud</groupId>
         <artifactId>spring-cloud-dependencies</artifactId>
         <version>Dalston.SR1</version>
         <type>pom</type>
         <scope>import</scope>
     </dependency>
  </dependencies>
</dependencyManagement>

然后在依赖里添加 Config client BOM

<dependencies>
  <dependency>
    <groupId>io.pivotal.spring.cloud</groupId>
    <artifactId>spring-cloud-services-starter-config-client</artifactId>
  </dependency>
</dependencies>

使用命令mvn dependency:tree查看依赖关系树

[INFO] +- io.pivotal.spring.cloud:spring-cloud-services-starter-config-client:jar:1.4.1.RELEASE:compile
[INFO] |  +- org.springframework.cloud:spring-cloud-config-client:jar:1.2.2.RELEASE:compile
[INFO] |  |  +- org.springframework.boot:spring-boot-autoconfigure:jar:1.4.2.RELEASE:compile
[INFO] |  |  +- org.springframework.cloud:spring-cloud-commons:jar:1.1.7.RELEASE:compile
[INFO] |  |  |  \- org.springframework.security:spring-security-crypto:jar:4.1.3.RELEASE:compile
[INFO] |  |  +- org.springframework.cloud:spring-cloud-context:jar:1.1.7.RELEASE:compile
[INFO] |  |  \- com.fasterxml.jackson.core:jackson-annotations:jar:2.8.4:compile
[INFO] |  +- org.springframework.security.oauth:spring-security-oauth2:jar:2.0.12.RELEASE:runtime
[INFO] |  |  +- org.springframework:spring-beans:jar:4.3.4.RELEASE:compile
[INFO] |  |  +- org.springframework:spring-context:jar:4.3.4.RELEASE:compile
[INFO] |  |  +- org.springframework.security:spring-security-core:jar:4.1.3.RELEASE:runtime
[INFO] |  |  |  \- aopalliance:aopalliance:jar:1.0:runtime
[INFO] |  |  +- org.springframework.security:spring-security-config:jar:4.1.3.RELEASE:runtime
[INFO] |  |  +- org.springframework.security:spring-security-web:jar:4.1.3.RELEASE:runtime
[INFO] |  |  +- commons-codec:commons-codec:jar:1.10:compile
[INFO] |  |  \- org.codehaus.jackson:jackson-mapper-asl:jar:1.9.13:runtime
[INFO] |  |     \- org.codehaus.jackson:jackson-core-asl:jar:1.9.13:runtime
[INFO] |  +- io.pivotal.spring.cloud:spring-cloud-services-cloudfoundry-connector:jar:1.4.1.RELEASE:compile
[INFO] |  |  +- io.pivotal.spring.cloud:spring-cloud-services-connector-core:jar:1.4.1.RELEASE:compile
[INFO] |  |  |  \- org.springframework.cloud:spring-cloud-core:jar:1.2.3.RELEASE:compile
[INFO] |  |  \- org.springframework.cloud:spring-cloud-cloudfoundry-connector:jar:1.2.3.RELEASE:compile
[INFO] |  +- io.pivotal.spring.cloud:spring-cloud-services-spring-connector:jar:1.4.1.RELEASE:compile
[INFO] |  |  +- org.projectlombok:lombok:jar:1.16.10:compile
[INFO] |  |  \- org.springframework.cloud:spring-cloud-spring-service-connector:jar:1.2.3.RELEASE:compile
[INFO] |  \- io.pivotal.spring.cloud:cloudfoundry-certificate-truster:jar:1.0.1.RELEASE:compile

假设我们已经获取到了配置文件，就可以在 Spring 程序里使用变量

@Value("${cook.special}")
String special;

Service Detection

至于如何做到把 Config Server 上的配置文件加载到我们的客户端应用程序里的，接下来分析。

在 CloudFoundry 上 push 此应用时会有这样的配置，把 Config Server 绑定给我们的程序

services:
  - config-server

这样 CloudFoundry 就会为此服务设置环境变量：使用命令 cf env cook 获取该应用的环境变量

$ cf env cook
Getting env variables for app cook in org tiven.wang / space development as i.tiven.wang@gmail.com...
OK

System-Provided:
{
"VCAP_SERVICES": {
 "p-config-server": [
  {
   "credentials": {
    "access_token_uri": "https://p-spring-cloud-services.uaa.run.pivotal.io/oauth/token",
    "client_id": "p-config-server-fde9103d-7c83-46d2-8744-86b5b81da6fa",
    "client_secret": "nZyy8XIvbAaz",
    "uri": "https://config-36050167-e8fb-47b4-8530-9f6b8b3ed40b.cfapps.io"
   },
   "label": "p-config-server",
   "name": "config-server",
   "plan": "standard",
   "provider": null,
   "syslog_drain_url": null,
   "tags": [
    "configuration",
    "spring-cloud"
   ],
   "volume_mounts": []
  }
 ]
}
}

{
"VCAP_APPLICATION": {
 "application_id": "74bb0f74-ff7d-4146-8591-19828838f828",
 "application_name": "cook",
 "application_uris": [
  "try-cf-cookie.cfapps.io"
 ],
 "application_version": "b46b9f88-f8e0-46e1-829a-396fca6c9431",
 "cf_api": "https://api.run.pivotal.io",
 "limits": {
  "disk": 1024,
  "fds": 16384,
  "mem": 1024
 },
 "name": "cook",
 "space_id": "b8ad7c89-2917-436b-930f-dac3d81f9ba5",
 "space_name": "development",
 "uris": [
  "try-cf-cookie.cfapps.io"
 ],
 "users": null,
 "version": "b46b9f88-f8e0-46e1-829a-396fca6c9431"
}
}

User-Provided:
SPRING_PROFILES_ACTIVE: dev

No running env variables have been set

No staging env variables have been set

VCAP_SERVICES　节点下代表所有服务的环境配置，其中 p-config-server 就是我们创建的配置服务器。

接下来该做的就是应用程序把这些信息拿去用。

Spring Cloud® Connectors

在 CloudFoundry 平台上为了从客户端应用里连接 Config Server，Spring Cloud Services 使用 Spring Cloud Connectors 里的 Spring Cloud Cloud Foundry Connector 去发现绑定到应用程序上的服务。

Spring Cloud Connectors 框架的总体架构如下图所示：

Image: spring-cloud-connectors-design

CloudConnector 实例会决定当前运行的云环境； ServiceConnectorCreator 和 ServiceInfoCreator 实例会根据 Service 的 tags 决定是否属于自己，然后创建相应的 ServiceConnector 和 ServiceInfo； ServiceConnector 指的是不同的服务自己不同的 Connector 类型，如 Database 的 DataSource 。

Spring Cloud Connectors uses the Java SPI to discover available connectors.

接下来，例如 Spring Cloud Config 组件中，创建的 ServiceInfo 会被相应的 ServiceInfoPropertySourceAdapter 组装成 PropertySource 添加到 Spring 的 ConfigurableEnvironment 环境中，继而被相关组件使用。

例如：Spring Cloud Config 会使用注解来把 ConfigurableEnvironment 环境中的变量识别成对象 @ConfigurationProperties("spring.cloud.config") 然后会自动配置利用，进行Config server client的创建。

Spring Cloud Config Client

Spring Cloud Config Client 组件会根据环境变量自动配置一个 ConfigServicePropertySourceLocator 实例进行 Config Server 的读取操作，然后把读取到的配置信息塞到 Spring ConfigurableEnvironment 的 PropertySources 里去；

Spring Cloud Config Client 组件同时还支持调用接口重试能力，它是通过 Spring Retry 项目组件来做的；

还可以通过 HealthIndicator 做 Health Check；

还可以通过配置 Spring Cloud Service Discovery 组件来自动获取 Config Server 的服务地址。

详细逻辑可以通过研读源代码获得了解。

Trying It Out

打包此 Maven 项目 mvn package;
部署之前更改 manifest.yml 中的host成你自己的应用程序地址
通过命令部署 cf push -p ./target/cook-0.0.1-SNAPSHOT.jar
应用程序成功部署后可以打开链接 http://try-cf-cookie.cfapps.io/restaurant 查看返回结果以校验配置正确：我们配置配置的 Spring Profile 是 dev 所以得到的结果是 “Today’s special is: Pickled Cactus“。

如果在 manifest.yml 中把 env 配置成 SPRING_PROFILES_ACTIVE: production 或者在 application.yml 把配置改成

spring:
  profiles: production

重新部署后再此访问可以看到结果的变化: 首先就要输入用户名密码，因为 Spring Cloud Config Client starter 包含了一个 Spring Security 依赖包，默认会使用 HTTP Basic authentication 来保护你的所有的应用程序 endpoints ，除非你配置成其他的安全设置。如何配置? 默认用户名为 user ，随机密码在 console 打印中有，形式如下

Using default security password: 78fa095d-3f4c-48b1-ad50-e24c31d5cf35

登录后可以看到输出结果变为了 “Today’s special is: Cake a la mode” 。

References

[1] Config Server for Pivotal Cloud Foundry http://docs.pivotal.io/spring-cloud-services/1-4/common/config-server/
[2] Project Configuration with Spring http://www.baeldung.com/project-configuration-with-spring
[3] Cloud Foundry Environment Variables https://docs.pivotal.io/pivotalcf/1-12/devguide/deploy-apps/environment-variable.html