Issue 519: Support multiple YamlConfigurationSercvices

[mikkokar]

Summary

Fixes: #519

Provides equivalent functionality to BackendServiceProxy when using YamlConfigurationFileService to configure styx from origins file.

• Add a new ingressObject attribute to YamlConfigurationFileService. It names the routing object serving as an entry point for backend services sourced from the yaml configuration service. In practice it is the ingress object is a PathPrefixRouter.

• When ingressObject is absent, the name is derived from YamlConfigurationFileService provider name as follows <name>-router.

• Rename source tag for generated routing objects. The source tag now specifies the provider object name instead of its type.

• Rename generated health check services. The names now have -monitor postfix. For example if the provider name is foo then the health check provider name will be foo-monitor.

Configuration Example

providers:
  zone1:
    type: YamlFileConfigurationService
    config:
      ingressObject: zone1Router
      originsFile: "/styx/config/origins/zone1.yaml"
  fallbackOriginsProvider:
    type: YamlFileConfigurationService
    config:
      ingressObject: fallbackRouter
      originsFile: "/styx/config/origins/zone2.yaml"
  zone3:
    type: YamlFileConfigurationService
    config:
      originsFile: "/styx/config/origins/zone3.yaml"


httpPipeline:
  type: ConditionRouter
  config:
    routes:
      - condition: header("abc") == "true"
        destination: zone1Router
      - condition: header("def") == "true"
        destination: zone3-router
    fallback: fallbackRouter

[chrisgresty]

Just a minor comment.
I would also say that the name handling is not always clear in general in the code, but I'm not sure what to do about that..

[chrisgresty]

This name parameter is ignored by the HC factory - perhaps make it clearer that the value here is not significant?

[mikkokar]

Thanks for spotting this. I have refactored so that a correct name is always passed in. Even if .build() ignores it.

[mikkokar]

Just a minor comment.
I would also say that the name handling is not always clear in general in the code, but I'm not sure what to do about that..

I tend to agree this can be improved. As always, I'm open for constructive feedback :-)