[SCB-1128] Omega discovers alpha service from eureka

[coolbeevip]

Get the access address of Alpah Server from Eureka Server
Turn this feautre on by set alpha.cluster.register.type=spring-cloud
First omega gets the Alpha address from Eureka with ${alpha.cluster.serviceId}
If omega can't get it in Eureka then use ${alpha.cluster.address}

Add dependencie

 <dependency>
      <groupId>org.apache.servicecomb.pack</groupId>
      <artifactId>omega-spring-starter</artifactId>
      <version>0.4.0-SNAPSHOT</version>
 </dependency>
 <dependency>
      <groupId>org.apache.servicecomb.pack</groupId>
      <artifactId>omega-spring-cloud-starter</artifactId>
      <version>0.4.0-SNAPSHOT</version>
 </dependency>

About AutoConfiguration

Deprecated @EnableOmega

add omega-spring-starter dependency, then it will automatically enabled omega,You can set omega.enabled=true/false to turn this feature ON or OFF

Add Alpha configuration to the application.yml

• Default Alpha use ${spring.application.name} as the Eureka serviceId

alpha.cluster.serviceId=servicecomb-alpha-server

• Define the registry type

When the value is spring-cloud, it is get from Eureka. otherwise use ${alpha.cluster.address}

alpha.cluster.register.type=spring-cloud

• e.g.

alpha:
  cluster:
    address: localhost:8080
    serviceId: servicecomb-alpha-server
    register:
      type: spring-cloud
omega:
  instance:
    instanceId: ${spring.application.name}-${spring.cloud.client.hostname}-${server.port}

Add Eureka Client configuration to the application.yml

eureka:
  client:
    service-url:
      defaultZone: http://127.0.0.1:8761/eureka

[coveralls]

Coverage increased (+0.03%) to 90.375% when pulling cea2b8a on coolbeevip:SCB-1128 into 43894d0 on apache:master.

[WillemJiang]

Need the license header, please take the application.yaml as an example.

[WillemJiang]

We already has the EnableOmega, so I don't think we need to add this annotation here.
We may need to find a way to enable the service discovery by looking up the configuration atomatically.

[coolbeevip]

Yes, I can use spring.factories

[coolbeevip]

Maybe we can let SpringFactoriesLoader automatically configure OmegaSpringConfig through spring.factories, so @EnableOmega is not needed

[WillemJiang]

I think we need to find a way to reuse the old configuration, it could be in our todo list.

[coolbeevip]

Maybe define an object AlphaClusterAddress, Attribute contains Alpha's address, registry center information...

Add AlphaClusterAddress to the parameters of AlphaClusterConfig

  AlphaClusterConfig alphaClusterConfig(
      @Value("${alpha.cluster.address:localhost:8080}") String[] addresses,
      @Value("${alpha.cluster.ssl.enable:false}") boolean enableSSL,
      @Value("${alpha.cluster.ssl.mutualAuth:false}") boolean mutualAuth,
      @Value("${alpha.cluster.ssl.cert:client.crt}") String cert,
      @Value("${alpha.cluster.ssl.key:client.pem}") String key,
      @Value("${alpha.cluster.ssl.certChain:ca.crt}") String certChain,
      @Lazy AlphaClusterAddress alphaClusterAddress,
      @Lazy MessageHandler handler,
      @Lazy TccMessageHandler tccMessageHandler) {
   ...
}

Define an default AlphaClusterAddress Bean in OmegaSpringConfig,it's Null
Define an default AlphaClusterAddress Bean in OmegaSpringEurekaConfig,it's from Eureka

use this AlphaClusterAddress if it is not empty, otherwise use the default ${alpha.cluster.address address}

[coolbeevip]

@WillemJiang I reconstructed the code according to your idea

[WillemJiang]

How can we implement the dynamic address lookup? I think we need to add the alphaClusterDiscovery address here.