Add mapping metadata of service (registered in Eureka) to ServiceMeta…

[ziebapawel]

Firstly I would like to thank you for creating this library. It's very helpful. Several months ago we've started to monitoring our applications by Prometheus. Most of the time Consul has been used as Discover Service but two weeks ago we've decided to use Eureka with Eureka Consul Adapter as Discovery Service. Our services are registered with additional metadata and we use them in relabeling phase of Prometheus. During relabeling phase we use following meta label __meta_consul_service_metadata_<key>. With Consul it works correctly but with Eureka with Eureka Consul Adapter it doesn't work as we expected. We noticed that metadata associated with service (registered in Eureka) appears as NodeMeta instead of ServiceMeta. In our opinion metadata of service registered in Eureka should appear as ServiceMeta because these metadata are associated with service, not with node of Consul.

We've made changes that make metadata of service (registered in Eureka) appears as ServiceMeta.

For backward compatibility we introduce following properties:

• eurekaConsulAdapter.useNodeMeta : boolean (default: false)
• eurekaConsulAdapter.nodeMetaPrefix : String (default: "")

Possible scenarios of usage:

1

• eurekaConsulAdapter.useNodeMeta is not set or is set to false
• eurekaConsulAdapter.nodeMetaPrefix in this case is not used each metadata of service (registered in Eureka) appears as ServiceMeta, NodeMeta map is empty

2

• eurekaConsulAdapter.useNodeMeta is set to true
• eurekaConsulAdapter.nodeMetaPrefix is not set (default value) or is set to "" (empty string) each metadata of service (registered in Eureka) appears as NodeMeta, ServiceMeta map is empty

3

• eurekaConsulAdapter.useNodeMeta is set to true
• eurekaConsulAdapter.nodeMetaPrefix is set to e.g. nodeMeta_ each metadata of service (registered in Eureka) is filtered according to the following rules:
  • metadata which key begins with nodeMeta_ is moved to NodeMeta map (during moving prefix is removed nodeMeta_k1 -> k1)
  • metadata which key not begins with nodeMeta_ is moved to ServiceMeta map

[tine2k]

Thanks for your PR @ziebapawel. Please give me a couple a days for the review. Work is very busy atm :(

[tine2k]

@ziebapawel I merged your PR and released your changes as version 1.3.0. Thanks for your contribution.