Spring Cloud Config Server 解析

概述

在常规单体项目开发中,我们会有很多配置,比如本地开发环境配置、测试环境配置、生产环境配置、开关配置等
通常我们都会放在resource文件夹下,在编译打包期间,把对应的profile打包进去。

在微服务环境下场景下,由于服务的拆分会衍生出N个服务,这样每个服务都需要去写配置文件,这样一来需要管理的配置文件数据急剧上升,上线后如果需要改一些配置,会很头疼。
然而这些都不是问题,Spring Cloud为我们提供了一个统一配置管理中心Spring Cloud Config 来解决这些问题

Spring Cloud Config 角色

config-server
Spring Cloud Config可以分成3个部分

  • 远程文件,git、subversion、native、vault
  • Config Server 配置中心
  • Config Client 配置客户端

Spring CLoud Config Server 启动分析

config-server

EnvironmentRepositoryConfiguration.java

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@Configuration
@ConditionalOnMissingBean(EnvironmentRepository.class)
protected static class DefaultRepositoryConfiguration {

@Autowired
private ConfigurableEnvironment environment;

@Autowired
private ConfigServerProperties server;

@Bean
public MultipleJGitEnvironmentRepository defaultEnvironmentRepository() {
MultipleJGitEnvironmentRepository repository = new MultipleJGitEnvironmentRepository(this.environment);
if (this.server.getDefaultLabel()!=null) {
repository.setDefaultLabel(this.server.getDefaultLabel());
}
return repository;
}
}
@Configuration
@Profile("native")
protected static class NativeRepositoryConfiguration {

@Autowired
private ConfigurableEnvironment environment;

@Bean
public NativeEnvironmentRepository nativeEnvironmentRepository() {
return new NativeEnvironmentRepository(this.environment);
}
}

@Configuration
@Profile("git")
protected static class GitRepositoryConfiguration extends DefaultRepositoryConfiguration {}

@Configuration
@Profile("subversion")
protected static class SvnRepositoryConfiguration {
@Autowired
private ConfigurableEnvironment environment;

@Autowired
private ConfigServerProperties server;

@Bean
public SvnKitEnvironmentRepository svnKitEnvironmentRepository() {
SvnKitEnvironmentRepository repository = new SvnKitEnvironmentRepository(this.environment);
if (this.server.getDefaultLabel()!=null) {
repository.setDefaultLabel(this.server.getDefaultLabel());
}
return repository;
}
}

@Configuration
@Profile("vault")
protected static class VaultConfiguration {
@Bean
public VaultEnvironmentRepository vaultEnvironmentRepository(HttpServletRequest request, EnvironmentWatch watch) {
return new VaultEnvironmentRepository(request, watch, new RestTemplate());
}
}

Spring Cloud Config 默认使用git来做配置存储, 还提供了subversion、native、vault3中存储方式
需要使用其它方式只需要在配置文件中指定profile

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spring:
cloud:
config:
profile:

Spring Cloud Config 默认使用MultipleJGitEnvironmentRepository类来对git上的配置进行加载

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protected File createBaseDir() {
try {
final File basedir = Files.createTempDirectory("config-repo-").toFile();
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
try {
FileUtils.delete(basedir, FileUtils.RECURSIVE);
}
catch (IOException e) {
AbstractScmAccessor.this.logger.warn(
"Failed to delete temporary directory on exit: " + e);
}
}
});
return basedir;
}
catch (IOException e) {
throw new IllegalStateException("Cannot create temp dir", e);
}
}

Spring Cloud Config在启动的时候会创建一个临时目录并且添加进了jvm的shutdown钩子中,在jvm容器停止的时候销毁这个目录

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@Override
public void afterPropertiesSet() throws Exception {
//git访问工厂
GitCredentialsProviderFactory credentialFactory = new GitCredentialsProviderFactory();
super.setGitCredentialsProvider(credentialFactory.createFor(getUri(),
getUsername(), getPassword(), getPassphrase()));
super.afterPropertiesSet();
for (String name : this.repos.keySet()) {
PatternMatchingJGitEnvironmentRepository repo = this.repos.get(name);
repo.setEnvironment(getEnvironment());
if (!StringUtils.hasText(repo.getName())) {
repo.setName(name);
}
if (repo.getPattern() == null || repo.getPattern().length == 0) {
repo.setPattern(new String[] { name });
}
if (getTimeout() != 0 && repo.getTimeout() == 0) {
repo.setTimeout(getTimeout());
}
String user = repo.getUsername();
String pass = repo.getPassword();
String passphrase = repo.getPassphrase();
if (user == null) {
user = getUsername();
pass = getPassword();
}
if (passphrase == null) {
passphrase = getPassphrase();
}
repo.setGitCredentialsProvider(credentialFactory.createFor(repo.getUri(),
user, pass, passphrase));
repo.afterPropertiesSet();
}
}

GitCredentialsProviderFactory git服务创建工厂,提供了

  • UsernamePasswordCredentialsProvider 用户名密码服务
  • PassphraseCredentialsProvider sshKey服务
  • AwsCodeCommitCredentialProvider awsCode服务

Config Server在接受到client请求后

  1. 判断git临时目录存不存,如果存在则定位到该目录否则创建目录并且定位到该目录
  2. 判断是否需要更新,如果是则fetch remote并且checkout否则just checkout
  3. 合并到分支
  4. 创建一个新的SpringApplication应用去返回Environment信息
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@RequestMapping("/{name}/{profiles:.*[^-].*}")
public Environment defaultLabel(@PathVariable String name,
@PathVariable String profiles) {
return labelled(name, profiles, null);
}

@RequestMapping("/{name}/{profiles}/{label:.*}")
public Environment labelled(@PathVariable String name, @PathVariable String profiles,
@PathVariable String label) {
if (label != null && label.contains("(_)")) {
// "(_)" is uncommon in a git branch name, but "/" cannot be matched
// by Spring MVC
label = label.replace("(_)", "/");
}
Environment environment = this.repository.findOne(name, profiles, label);
return environment;
}

Spring CLoud Config Client 启动分析

在spring.factories中定义了引导配置类ConfigServiceBootstrapConfiguration,它的作用是在SpringBoot上下文启动时读取resources目录下的bootstrap.properties文件,取出前缀名为spring.cloud.config的配置项,这些配置项通常包含config server的节点信息、连接该节点所需要的权限配置以及客户端所要抓取的配置信息,并以此初始化ConfigClientProperties:

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@Bean
public ConfigClientProperties configClientProperties() {
ConfigClientProperties client = new ConfigClientProperties(this.environment);
return client;
}

@Bean
@ConditionalOnProperty(value = "spring.cloud.config.enabled", matchIfMissing = true)
public ConfigServicePropertySourceLocator configServicePropertySource(ConfigClientProperties properties) {
ConfigServicePropertySourceLocator locator = new ConfigServicePropertySourceLocator(
properties);
return locator;
}

Spring Boot 在上下文刷新前会初始化应用上下文,其中在PropertySourceBootstrapConfiguration类中
ConfigServicePropertySourceLocator类中的locate方法会被调用,从而保证在上下文刷新前可以拿到配置信息

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@Override
public void initialize(ConfigurableApplicationContext applicationContext) {
CompositePropertySource composite = new CompositePropertySource(
BOOTSTRAP_PROPERTY_SOURCE_NAME);
AnnotationAwareOrderComparator.sort(this.propertySourceLocators);
boolean empty = true;
ConfigurableEnvironment environment = applicationContext.getEnvironment();
for (PropertySourceLocator locator : this.propertySourceLocators) {
PropertySource<?> source = null;
source = locator.locate(environment);
if (source == null) {
continue;
}
logger.info("Located property source: " + source);
composite.addPropertySource(source);
empty = false;
}
...
}

Spring Cloud Config使用RestTemplate来做配置的获取,默认读取超时时间为3m5s,可能在下一个版本可以去配置
请求默认Server地址为http://ip:port/{name}/{profile}
请求返回Environment对象并把它放到CompositePropertySource中

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@Override
@Retryable(interceptor = "configServerRetryInterceptor")
public org.springframework.core.env.PropertySource<?> locate(
org.springframework.core.env.Environment environment) {
ConfigClientProperties properties = this.defaultProperties.override(environment);
CompositePropertySource composite = new CompositePropertySource("configService");
RestTemplate restTemplate = this.restTemplate == null ? getSecureRestTemplate(properties)
: this.restTemplate;
Exception error = null;
String errorBody = null;
logger.info("Fetching config from server at: " + properties.getRawUri());
try {
String[] labels = new String[] { "" };
if (StringUtils.hasText(properties.getLabel())) {
labels = StringUtils.commaDelimitedListToStringArray(properties.getLabel());
}

String state = ConfigClientStateHolder.getState();

// Try all the labels until one works
for (String label : labels) {
Environment result = getRemoteEnvironment(restTemplate,
properties, label.trim(), state);
if (result != null) {
logger.info(String.format("Located environment: name=%s, profiles=%s, label=%s, version=%s, state=%s",
result.getName(),
result.getProfiles() == null ? "" : Arrays.asList(result.getProfiles()),
result.getLabel(), result.getVersion(), result.getState()));

if (result.getPropertySources() != null) { // result.getPropertySources() can be null if using xml
for (PropertySource source : result.getPropertySources()) {
@SuppressWarnings("unchecked")
Map<String, Object> map = (Map<String, Object>) source
.getSource();
composite.addPropertySource(new MapPropertySource(source
.getName(), map));
}
}

if (StringUtils.hasText(result.getState()) || StringUtils.hasText(result.getVersion())) {
HashMap<String, Object> map = new HashMap<>();
putValue(map, "config.client.state", result.getState());
putValue(map, "config.client.version", result.getVersion());
composite.addFirstPropertySource(new MapPropertySource("configClient", map));
}
return composite;
}
}
}
catch (HttpServerErrorException e) {
error = e;
if (MediaType.APPLICATION_JSON.includes(e.getResponseHeaders()
.getContentType())) {
errorBody = e.getResponseBodyAsString();
}
}
catch (Exception e) {
error = e;
}
if (properties.isFailFast()) {
throw new IllegalStateException(
"Could not locate PropertySource and the fail fast property is set, failing",
error);
}
logger.warn("Could not locate PropertySource: "
+ (errorBody == null ? error==null ? "label not found" : error.getMessage() : errorBody));
return null;

}
您的支持就是我的动力