Spring Cloud Config Server 源码分析 : 配置中心如何提供配置
本文主要从一些spring-cloud-config-server 包中的注解和类来分析配置中心是如何对外提供配置。
从@EnableConfigServer开始
为了让一个spring boot应用成为配置中心，我们需要使用@EnableConfigServer注解
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(ConfigServerConfiguration.class)
public @interface EnableConfigServer {
}
可以看出，它引入了ConfigServerConfiguration
@Configuration
public class ConfigServerConfiguration {
class Marker {}
@Bean
public Marker enableConfigServerMarker() {
return new Marker();
}
}
ConfigServerConfiguration 装配了一个MarkerBean。这个bean则有开启了ConfigServerAutoConfiguration
@Configuration
@ConditionalOnBean(ConfigServerConfiguration.Marker.class)
@EnableConfigurationProperties(ConfigServerProperties.class)
@Import({ EnvironmentRepositoryConfiguration.class, CompositeConfiguration.class, ResourceRepositoryConfiguration.class,
ConfigServerEncryptionConfiguration.class, ConfigServerMvcConfiguration.class, TransportConfiguration.class })
public class ConfigServerAutoConfiguration {
}
这里又引入了多个配置类，包括:
EnvironmentRepositoryConfiguration
CompositeConfiguration
ResourceRepositoryConfiguration
ConfigServerEncryptionConfiguration
ConfigServerMvcConfiguration
TransportConfiguration
接下来介绍EnvironmentRepositoryConfiguration
EnvironmentRepositoryConfiguration
EnvironmentRepositoryConfiguration是配置中心的关键Configuration类。这个配置类中包含很多实现了EnvironmentRepository接口的类，每个实现类都对应一种类型(git/svn/navtie/vault)的配置。 EnvironmentRepositoryConfiguration通过profile注解（对当前应用的环境）决定使用装配哪个EnvironmentRepository Bean。默认是MultipleJGitEnvironmentRepository
@Configuration
public class EnvironmentRepositoryConfiguration {
@Bean
@ConditionalOnProperty(value = "spring.cloud.config.server.health.enabled", matchIfMissing = true)
public ConfigServerHealthIndicator configServerHealthIndicator(EnvironmentRepository repository) {
return new ConfigServerHealthIndicator(repository);
}
@Configuration
@ConditionalOnMissingBean(EnvironmentRepository.class)
protected static class DefaultRepositoryConfiguration {
@Autowired
private ConfigurableEnvironment environment;
@Autowired
private ConfigServerProperties server;
@Autowired(required = false)
private TransportConfigCallback transportConfigCallback;
@Bean
public MultipleJGitEnvironmentRepository defaultEnvironmentRepository() {
MultipleJGitEnvironmentRepository repository = new MultipleJGitEnvironmentRepository(this.environment);
repository.setTransportConfigCallback(this.transportConfigCallback);
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());
}
}
@Configuration
@ConditionalOnProperty(value = "spring.cloud.config.server.consul.watch.enabled")
protected static class ConsulEnvironmentWatchConfiguration {
@Bean
public EnvironmentWatch environmentWatch() {
return new ConsulEnvironmentWatch();
}
}
@Configuration
@ConditionalOnMissingBean(EnvironmentWatch.class)
protected static class DefaultEnvironmentWatch {
@Bean
public EnvironmentWatch environmentWatch() {
return new EnvironmentWatch.Default();
}
}
}
EnvironmentRepository
EnvironmentRepository是一个配置管理仓库接口，抽象了获取配置的方法:
Environment findOne(String application, String profile, String label);
它的实现类有很多，如下图所示:
从名字中大概可以看出，这些类应该是用于加载不同类型的配置（后面会再介绍）。
有了获取配置的类，还差对外提供接口的类，就是EnvironmentController
入口：EnvironmentController
EnvironmentController是spring-cloud-config-server包的一个controller，其他服务一般是通过这个controller获取相应配置。
@RestController
@RequestMapping(method = RequestMethod.GET, path = "${spring.cloud.config.server.prefix:}")
public class EnvironmentController {
private EnvironmentRepository repository;
private ObjectMapper objectMapper;
public EnvironmentController(EnvironmentRepository repository,
ObjectMapper objectMapper) {
this.repository = repository;
this.objectMapper = objectMapper;
}
// 获取配置的接口
...
}
它的关键成员变量有两个：
一般情况Spring为EnvironmentController注入的类是EnvironmentEncryptorEnvironmentRepository。ObjectMapper用于当请求json格式的配置时的序列化。
EnvironmentController提供了多种获取配置的方法，这些方法主要接受application profile label这三个（或者更少）的参数，这三个参数的具体含义可以参考官网的说明，下面列举了部分方法：
@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;
}
我们访问http://localhost:8081/config/mysql/dev(这是作者的配置，每个人可能不一样), 进入defaultLabel方法，它会再调用labelled方法（由于没有制定label参数，所以label传了个null）。
@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;
}
在labelled方法中，会调用repository的findOne()来加载配置，然后返回给配置获取方。
各式各样的配置仓库类
EnvironmentEncryptorEnvironmentRepository
前面提到spring config 通过EnvironmentEncryptorEnvironmentRepository加载配置
public class EnvironmentEncryptorEnvironmentRepository implements EnvironmentRepository {
private EnvironmentRepository delegate;
private EnvironmentEncryptor environmentEncryptor;
public EnvironmentEncryptorEnvironmentRepository(EnvironmentRepository delegate,
EnvironmentEncryptor environmentEncryptor) {
this.delegate = delegate;
this.environmentEncryptor = environmentEncryptor;
}
@Override
public Environment findOne(String name, String profiles, String label) {
Environment environment = this.delegate.findOne(name, profiles, label);
if (this.environmentEncryptor != null) {
environment = this.environmentEncryptor.decrypt(environment);
}
if (!this.overrides.isEmpty()) {
environment.addFirst(new PropertySource("overrides", this.overrides));
}
return environment;
}
}
它有一个解密器environmentEncryptor用于对加密存放的配置进行解密，另外包含一个EnvironmentRepository的实现类delegate，这里注入的类是SearchPathCompositeEnvironmentRepository
SearchPathCompositeEnvironmentRepository
SearchPathCompositeEnvironmentRepository本身并没有findOne()方法，由它的父类CompositeEnvironmentRepository实现。
public class SearchPathCompositeEnvironmentRepository extends CompositeEnvironmentRepository implements SearchPathLocator {
public SearchPathCompositeEnvironmentRepository(List<EnvironmentRepository> environmentRepositories) {
super(environmentRepositories);
}
}
SearchPathCompositeEnvironmentRepository
CompositeEnvironmentRepository有一个EnvironmentRepository的列表。从它的findOne()方法可以看出：当有多个配置存放方式时，CompositeEnvironmentRepository会遍历所有EnvironmentRepository来获取所有配置。
public class CompositeEnvironmentRepository implements EnvironmentRepository {
protected List<EnvironmentRepository> environmentRepositories;
public CompositeEnvironmentRepository(List<EnvironmentRepository> environmentRepositories) {
//Sort the environment repositories by the priority
Collections.sort(environmentRepositories, OrderComparator.INSTANCE);
this.environmentRepositories = environmentRepositories;
}
@Override
public Environment findOne(String application, String profile, String label) {
Environment env = new Environment(application, new String[]{profile}, label, null, null);
if(environmentRepositories.size() == 1) {
Environment envRepo = environmentRepositories.get(0).findOne(application, profile, label);
env.addAll(envRepo.getPropertySources());
env.setVersion(envRepo.getVersion());
env.setState(envRepo.getState());
} else {
for (EnvironmentRepository repo : environmentRepositories) {
env.addAll(repo.findOne(application, profile, label).getPropertySources());
}
}
return env;
}
}
小结一下：虽然实现了EnvironmentRepository接口。但EnvironmentEncryptorEnvironmentRepository只是一个代理， SearchPathCompositeEnvironmentRepository/CompositeEnvironmentRepository也没有具体加载配置的逻辑。
而真正加载配置的类存放在CompositeEnvironmentRepository的environmentRepositories列表。
包括：NativeEnvironmentRepository: 获取本地配置；SvnRepositoryConfiguration: 获取存放在svn中的配置；VaultEnvironmentRepository: 获取存放在vault中的配置；GitRepositoryConfiguration:获取存放在git中的配置；
接下来介绍NativeEnvironmentRepository。
NativeEnvironmentRepository
NativeEnvironmentRepository 用于加载本地(native)配置。它加载配置时，其实是以特定环境（传入的profile）启动了另外一个微型spring boot应用，通过这个应用获取所有的配置，然后调用clean过滤，得到所需配置。
@ConfigurationProperties("spring.cloud.config.server.native")
public class NativeEnvironmentRepository implements EnvironmentRepository, SearchPathLocator, Ordered {
@Override
public Environment findOne(String config, String profile, String label) {
SpringApplicationBuilder builder = new SpringApplicationBuilder(
PropertyPlaceholderAutoConfiguration.class);
ConfigurableEnvironment environment = getEnvironment(profile);
builder.environment(environment);
builder.web(false).bannerMode(Mode.OFF);
if (!logger.isDebugEnabled()) {
// Make the mini-application startup less verbose
builder.logStartupInfo(false);
}
String[] args = getArgs(config, profile, label);
// Explicitly set the listeners (to exclude logging listener which would change
// log levels in the caller)
builder.application()
.setListeners(Arrays.asList(new ConfigFileApplicationListener()));
ConfigurableApplicationContext context = builder.run(args);
environment.getPropertySources().remove("profiles");
try {
return clean(new PassthruEnvironmentRepository(environment).findOne(config,
profile, label));
}
finally {
context.close();
}
}
private ConfigurableEnvironment getEnvironment(String profile) {
ConfigurableEnvironment environment = new StandardEnvironment();
environment.getPropertySources()
.addFirst(new MapPropertySource("profiles",
Collections.<String, Object>singletonMap("spring.profiles.active",
profile)));
return environment;
}
protected Environment clean(Environment value) {
Environment result = new Environment(value.getName(), value.getProfiles(),
value.getLabel(), this.version, value.getState());
for (PropertySource source : value.getPropertySources()) {
String name = source.getName();
if (this.environment.getPropertySources().contains(name)) {
continue;
}
name = name.replace("applicationConfig: [", "");
name = name.replace("]", "");
if (this.searchLocations != null) {
boolean matches = false;
String normal = name;
if (normal.startsWith("file:")) {
normal = StringUtils
.cleanPath(new File(normal.substring("file:".length()))
.getAbsolutePath());
}
String profile = result.getProfiles() == null ? null
: StringUtils.arrayToCommaDelimitedString(result.getProfiles());
for (String pattern : getLocations(result.getName(), profile,
result.getLabel()).getLocations()) {
if (!pattern.contains(":")) {
pattern = "file:" + pattern;
}
if (pattern.startsWith("file:")) {
pattern = StringUtils
.cleanPath(new File(pattern.substring("file:".length()))
.getAbsolutePath())
+ "/";
}
if (logger.isTraceEnabled()) {
logger.trace("Testing pattern: " + pattern
+ " with property source: " + name);
}
if (normal.startsWith(pattern)
&& !normal.substring(pattern.length()).contains("/")) {
matches = true;
break;
}
}
if (!matches) {
// Don't include this one: it wasn't matched by our search locations
if (logger.isDebugEnabled()) {
logger.debug("Not adding property source: " + name);
}
continue;
}
}
logger.info("Adding property source: " + name);
result.add(new PropertySource(name, source.getSource()));
}
return result;
}
}