1.简介
1.1 Consul is a tool for service discovery and configuration. Consul is distributed, highly available, and extremely scalable.
Consul provides several key features:
Service Discovery - Consul makes it simple for services to register themselves and to discover other services via a DNS or HTTP interface. External services such as SaaS providers can be registered as well.
Health Checking - Health Checking enables Consul to quickly alert operators about any issues in a cluster. The integration with service discovery prevents routing traffic to unhealthy hosts and enables service level circuit breakers.
Key/Value Storage - A flexible key/value store enables storing dynamic configuration, feature flagging, coordination, leader election and more. The simple HTTP API makes it easy to use anywhere.
Multi-Datacenter - Consul is built to be datacenter aware, and can support any number of regions without complex configuration.
Consul runs on Linux, Mac OS X, FreeBSD, Solaris, and Windows.
1.2 consul-api
Java client for Consul HTTP API (http://consul.io)
Supports all API endpoints (http://www.consul.io/docs/agent/http.html), all consistency modes and parameters (tags, datacenters etc.)
1.3 整体架构
2.源码分析
主要工程：
2.1 spring-cloud-consul-config
spring.factories
# Auto Configuration
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.consul.config.ConsulConfigAutoConfiguration # Bootstrap Configuration
org.springframework.cloud.bootstrap.BootstrapConfiguration=\
org.springframework.cloud.consul.config.ConsulConfigBootstrapConfiguration
2.1.1 ConsulConfigAutoConfiguration自动配置
@Configuration
@ConditionalOnConsulEnabled
@ConditionalOnProperty(name = "spring.cloud.consul.config.enabled", matchIfMissing = true)
public class ConsulConfigAutoConfiguration { @Configuration
@ConditionalOnClass(RefreshEndpoint.class)
protected static class ConsulRefreshConfiguration {
@Bean
@ConditionalOnProperty(name = "spring.cloud.consul.config.watch.enabled", matchIfMissing = true)
public ConfigWatch configWatch(ConsulConfigProperties properties,
ConsulPropertySourceLocator locator, ConsulClient consul) {
return new ConfigWatch(properties, consul, locator.getContextIndexes());
}
}
}
其中，ConfigWatch的主要代码如下：
@Scheduled(fixedDelayString = "${spring.cloud.consul.config.watch.delay:1000}")
public void watchConfigKeyValues() {
if (this.running.get()) {
for (String context : this.consulIndexes.keySet()) {
// turn the context into a Consul folder path (unless our config format are FILES)
if (properties.getFormat() != FILES && !context.endsWith("/")) {
context = context + "/";
}
try {
Long currentIndex = this.consulIndexes.get(context);
if (currentIndex == null) {
currentIndex = -1L;
}
// use the consul ACL token if found
String aclToken = properties.getAclToken();
if (StringUtils.isEmpty(aclToken)) {
aclToken = null;
}
Response<List<GetValue>> response = this.consul.getKVValues(context, aclToken,
new QueryParams(this.properties.getWatch().getWaitTime(),
currentIndex));
// if response.value == null, response was a 404, otherwise it was a 200
// reducing churn if there wasn't anything
if (response.getValue() != null && !response.getValue().isEmpty()) {
Long newIndex = response.getConsulIndex();
if (newIndex != null && !newIndex.equals(currentIndex)) {
// don't publish the same index again, don't publish the first time (-1) so index can be primed
if (!this.consulIndexes.containsValue(newIndex) && !currentIndex.equals(-1L)) {
RefreshEventData data = new RefreshEventData(context, currentIndex, newIndex);
this.publisher.publishEvent(new RefreshEvent(this, data, data.toString()));
}
this.consulIndexes.put(context, newIndex);
}
}
} catch (Exception e) {
// only fail fast on the initial query, otherwise just log the error
if (firstTime && this.properties.isFailFast()) {
log.error("Fail fast is set and there was an error reading configuration from consul.");
ReflectionUtils.rethrowRuntimeException(e);
} else if (log.isTraceEnabled()) {
log.trace("Error querying consul Key/Values for context '" + context + "'", e);
} else if (log.isWarnEnabled()) {
// simplified one line log message in the event of an agent failure
log.warn("Error querying consul Key/Values for context '" + context + "'. Message: " + e.getMessage());
}
}
}
}
firstTime = false;
}
2.1.2 启动配置ConsulConfigBootstrapConfiguration
定义：
@Configuration
@ConditionalOnConsulEnabled
public class ConsulConfigBootstrapConfiguration { @Configuration
@EnableConfigurationProperties
@Import(ConsulAutoConfiguration.class)
@ConditionalOnProperty(name = "spring.cloud.consul.config.enabled", matchIfMissing = true)
protected static class ConsulPropertySourceConfiguration {
@Autowired
private ConsulClient consul; @Bean
public ConsulConfigProperties consulConfigProperties() {
return new ConsulConfigProperties();
} @Bean
public ConsulPropertySourceLocator consulPropertySourceLocator(
ConsulConfigProperties consulConfigProperties) {
return new ConsulPropertySourceLocator(consul, consulConfigProperties);
}
}
}
其中，ConsulPropertySourceLocator主要流程
@Override
@Retryable(interceptor = "consulRetryInterceptor")
public PropertySource<?> locate(Environment environment) {
if (environment instanceof ConfigurableEnvironment) {
ConfigurableEnvironment env = (ConfigurableEnvironment) environment;
RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env); String appName = properties.getName(); if (appName == null) {
appName = propertyResolver.getProperty("spring.application.name");
} List<String> profiles = Arrays.asList(env.getActiveProfiles()); String prefix = this.properties.getPrefix(); List<String> suffixes = new ArrayList<>();
if (this.properties.getFormat() != FILES) {
suffixes.add("/");
} else {
suffixes.add(".yml");
suffixes.add(".yaml");
suffixes.add(".properties");
} String defaultContext = prefix + "/" + this.properties.getDefaultContext();
for (String suffix : suffixes) {
this.contexts.add(defaultContext + suffix);
}
for (String suffix : suffixes) {
addProfiles(this.contexts, defaultContext, profiles, suffix);
} String baseContext = prefix + "/" + appName;
for (String suffix : suffixes) {
this.contexts.add(baseContext + suffix);
}
for (String suffix : suffixes) {
addProfiles(this.contexts, baseContext, profiles, suffix);
} Collections.reverse(this.contexts); CompositePropertySource composite = new CompositePropertySource("consul"); for (String propertySourceContext : this.contexts) {
try {
ConsulPropertySource propertySource = null;
if (this.properties.getFormat() == FILES) {
Response<GetValue> response = this.consul.getKVValue(propertySourceContext, this.properties.getAclToken());
addIndex(propertySourceContext, response.getConsulIndex());
if (response.getValue() != null) {
ConsulFilesPropertySource filesPropertySource = new ConsulFilesPropertySource(propertySourceContext, this.consul, this.properties);
filesPropertySource.init(response.getValue());
propertySource = filesPropertySource;
}
} else {
propertySource = create(propertySourceContext, contextIndex);
}
if (propertySource != null) {
composite.addPropertySource(propertySource);
}
} catch (Exception e) {
if (this.properties.isFailFast()) {
log.error("Fail fast is set and there was an error reading configuration from consul.");
ReflectionUtils.rethrowRuntimeException(e);
} else {
log.warn("Unable to load consul config from "+ propertySourceContext, e);
}
}
} return composite;
}
return null;
}
2.2 spring-cloud-consul-core
spring.factories
# Auto Configuration
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.consul.ConsulAutoConfiguration
实现如下：
@Configuration
@EnableConfigurationProperties
@ConditionalOnConsulEnabled
public class ConsulAutoConfiguration { @Bean
@ConditionalOnMissingBean
public ConsulProperties consulProperties() {
return new ConsulProperties();
} @Bean
@ConditionalOnMissingBean
public ConsulClient consulClient(ConsulProperties consulProperties) {
return new ConsulClient(consulProperties.getHost(), consulProperties.getPort());
} @Configuration
@ConditionalOnClass(Endpoint.class)
protected static class ConsulHealthConfig { @Bean
@ConditionalOnMissingBean
@ConditionalOnEnabledEndpoint("consul")
public ConsulEndpoint consulEndpoint(ConsulClient consulClient) {
return new ConsulEndpoint(consulClient);
} @Bean
@ConditionalOnMissingBean
@ConditionalOnEnabledHealthIndicator("consul")
public ConsulHealthIndicator consulHealthIndicator(ConsulClient consulClient) {
return new ConsulHealthIndicator(consulClient);
}
} @ConditionalOnClass({ Retryable.class, Aspect.class, AopAutoConfiguration.class })
@Configuration
@EnableRetry(proxyTargetClass = true)
@Import(AopAutoConfiguration.class)
@EnableConfigurationProperties(RetryProperties.class)
protected static class RetryConfiguration { @Bean(name = "consulRetryInterceptor")
@ConditionalOnMissingBean(name = "consulRetryInterceptor")
public RetryOperationsInterceptor consulRetryInterceptor(
RetryProperties properties) {
return RetryInterceptorBuilder
.stateless()
.backOffOptions(properties.getInitialInterval(),
properties.getMultiplier(), properties.getMaxInterval())
.maxAttempts(properties.getMaxAttempts()).build();
}
}
}
定义ConsulProperties、consulClient、ConsulEndpoint、ConsulHealthIndicator、RetryOperationsInterceptor
2.3 spring-cloud-consul-discovery
spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.consul.discovery.RibbonConsulAutoConfiguration,\
org.springframework.cloud.consul.discovery.configclient.ConsulConfigServerAutoConfiguration,\
org.springframework.cloud.consul.serviceregistry.ConsulAutoServiceRegistrationAutoConfiguration,\
org.springframework.cloud.consul.serviceregistry.ConsulServiceRegistryAutoConfiguration # Discovery Client Configuration
org.springframework.cloud.client.discovery.EnableDiscoveryClient=\
org.springframework.cloud.consul.discovery.ConsulDiscoveryClientConfiguration org.springframework.cloud.bootstrap.BootstrapConfiguration=\
org.springframework.cloud.consul.discovery.configclient.ConsulDiscoveryClientConfigServiceBootstrapConfiguration
2.3.1 ConsulRibbonClientConfiguration
@Configuration
@EnableConfigurationProperties
@ConditionalOnConsulEnabled
@ConditionalOnBean(SpringClientFactory.class)
@ConditionalOnProperty(value = "spring.cloud.consul.ribbon.enabled", matchIfMissing = true)
@AutoConfigureAfter(RibbonAutoConfiguration.class)
@RibbonClients(defaultConfiguration = ConsulRibbonClientConfiguration.class)
public class RibbonConsulAutoConfiguration { }
2.3.2 ConsulConfigServerAutoConfiguration for config server
/**
* Extra configuration for config server if it happens to be registered with Consul.
*
* @author Dave Syer
*/
@Configuration
@EnableConfigurationProperties
@ConditionalOnClass({ ConsulDiscoveryProperties.class, ConsulClient.class,
ConfigServerProperties.class })
public class ConsulConfigServerAutoConfiguration { @Autowired(required = false)
private ConsulDiscoveryProperties properties; @Autowired(required = false)
private ConfigServerProperties server; @PostConstruct
public void init() {
if (this.properties == null || this.server == null) {
return;
}
String prefix = this.server.getPrefix();
if (StringUtils.hasText(prefix)) {
this.properties.getTags().add("configPath="+prefix);
}
} }
2.3.3 ConsulAutoServiceRegistrationAutoConfiguration
@Configuration
@ConditionalOnBean(AutoServiceRegistrationProperties.class)
@ConditionalOnMissingBean(type = "org.springframework.cloud.consul.discovery.ConsulLifecycle")
@ConditionalOnConsulEnabled
@ConditionalOnProperty(value = "spring.cloud.service-registry.auto-registration.enabled", matchIfMissing = true)
@AutoConfigureAfter(ConsulServiceRegistryAutoConfiguration.class)
public class ConsulAutoServiceRegistrationAutoConfiguration { @Bean
@ConditionalOnMissingBean
public ConsulAutoServiceRegistration consulAutoServiceRegistration(ConsulServiceRegistry registry, ConsulDiscoveryProperties properties, ConsulAutoRegistration consulRegistration) {
return new ConsulAutoServiceRegistration(registry, properties, consulRegistration);
} @Bean
@ConditionalOnMissingBean
public ConsulAutoRegistration consulRegistration(ConsulDiscoveryProperties properties, ApplicationContext applicationContext,
ServletContext servletContext, HeartbeatProperties heartbeatProperties) {
return ConsulAutoRegistration.registration(properties, applicationContext, servletContext, heartbeatProperties);
} }
定义了ConsulAutoServiceRegistration、ConsulAutoRegistration
2.3.4 ConsulServiceRegistryAutoConfiguration
@Configuration
@ConditionalOnConsulEnabled
@ConditionalOnProperty(value = "spring.cloud.service-registry.enabled", matchIfMissing = true)
@AutoConfigureBefore(ServiceRegistryAutoConfiguration.class)
public class ConsulServiceRegistryAutoConfiguration { @Autowired(required = false)
private TtlScheduler ttlScheduler; @Bean
@ConditionalOnMissingBean
public ConsulServiceRegistry consulServiceRegistry(ConsulClient consulClient, ConsulDiscoveryProperties properties,
HeartbeatProperties heartbeatProperties) {
return new ConsulServiceRegistry(consulClient, properties, ttlScheduler, heartbeatProperties);
} @Bean
@ConditionalOnMissingBean
@ConditionalOnProperty("spring.cloud.consul.discovery.heartbeat.enabled")
public TtlScheduler ttlScheduler(ConsulClient consulClient, HeartbeatProperties heartbeatProperties) {
return new TtlScheduler(heartbeatProperties, consulClient);
} @Bean
@ConditionalOnMissingBean
public HeartbeatProperties heartbeatProperties() {
return new HeartbeatProperties();
} @Bean
@ConditionalOnMissingBean
public ConsulDiscoveryProperties consulDiscoveryProperties(InetUtils inetUtils) {
return new ConsulDiscoveryProperties(inetUtils);
} }
定义了 ConsulServiceRegistry、TtlScheduler、HeartbeatProperties、ConsulDiscoveryProperties
2.3.5 客户端发现ConsulDiscoveryClientConfiguration
@Configuration
@ConditionalOnConsulEnabled
@ConditionalOnProperty(value = "spring.cloud.consul.discovery.enabled", matchIfMissing = true)
@EnableConfigurationProperties
public class ConsulDiscoveryClientConfiguration { @Autowired
private ConsulClient consulClient; @Autowired(required = false)
private ServerProperties serverProperties; @Bean
@ConditionalOnMissingBean
@ConditionalOnProperty("spring.cloud.consul.discovery.heartbeat.enabled")
//TODO: move to service-registry for Edgware
public TtlScheduler ttlScheduler(HeartbeatProperties heartbeatProperties) {
return new TtlScheduler(heartbeatProperties, consulClient);
} @Bean
//TODO: move to service-registry for Edgware
public HeartbeatProperties heartbeatProperties() {
return new HeartbeatProperties();
} @Bean
//TODO: Split appropriate values to service-registry for Edgware
public ConsulDiscoveryProperties consulDiscoveryProperties(InetUtils inetUtils) {
return new ConsulDiscoveryProperties(inetUtils);
} @Bean
@ConditionalOnMissingBean
public ConsulDiscoveryClient consulDiscoveryClient(ConsulDiscoveryProperties discoveryProperties, final ApplicationContext context) {
ConsulDiscoveryClient discoveryClient = new ConsulDiscoveryClient(consulClient,
discoveryProperties, new LifecycleRegistrationResolver(context));
discoveryClient.setServerProperties(serverProperties); //null ok
return discoveryClient;
} class LifecycleRegistrationResolver implements ConsulDiscoveryClient.LocalResolver {
private ApplicationContext context; public LifecycleRegistrationResolver(ApplicationContext context) {
this.context = context;
} @Override
public String getInstanceId() {
ConsulRegistration registration = getBean(ConsulRegistration.class);
if (registration != null) {
return registration.getInstanceId();
}
ConsulLifecycle lifecycle = getBean(ConsulLifecycle.class);
if (lifecycle != null) {
return lifecycle.getInstanceId();
}
throw new IllegalStateException("Must have one of ConsulRegistration or ConsulLifecycle");
} @Override
public Integer getPort() {
ConsulRegistration registration = getBean(ConsulRegistration.class);
if (registration != null) {
return registration.getService().getPort();
}
ConsulLifecycle lifecycle = getBean(ConsulLifecycle.class);
if (lifecycle != null) {
return lifecycle.getConfiguredPort();
}
throw new IllegalStateException("Must have one of ConsulRegistration or ConsulLifecycle");
} <T> T getBean(Class<T> type) {
try {
return context.getBean(type);
} catch (NoSuchBeanDefinitionException e) {
}
return null;
}
} @Bean
@ConditionalOnMissingBean
@ConditionalOnProperty(name = "spring.cloud.consul.discovery.catalogServicesWatch.enabled", matchIfMissing = true)
public ConsulCatalogWatch consulCatalogWatch(
ConsulDiscoveryProperties discoveryProperties) {
return new ConsulCatalogWatch(discoveryProperties, consulClient);
}
}
2.3.6 ConsulDiscoveryClientConfigServiceBootstrapConfiguration
/**
* Helper for config client that wants to lookup the config server via discovery.
*
* @author Spencer Gibb
*/
@ConditionalOnClass(ConfigServicePropertySourceLocator.class)
@ConditionalOnProperty(value = "spring.cloud.config.discovery.enabled", matchIfMissing = false)
@Configuration
@Import({ ConsulAutoConfiguration.class, ConsulDiscoveryClientConfiguration.class})
public class ConsulDiscoveryClientConfigServiceBootstrapConfiguration { @Bean
public ConsulDiscoveryProperties consulDiscoveryProperties(InetUtils inetUtils) {
ConsulDiscoveryProperties properties = new ConsulDiscoveryProperties(inetUtils);
// for bootstrap, lifecycle (and hence registration) is not needed, just discovery client
properties.getLifecycle().setEnabled(false);
return properties;
}
}
参考文献
【1】https://github.com/hashicorp/consul
【2】https://github.com/Ecwid/consul-api
【3】https://www.consul.io/api/index.html