[jaeger] Have an ability to make collector svc headless

[spacentropy]

Hi.
gRPC client balancing requires headless services in order to work. More info here - https://kubernetes.io/blog/2018/11/07/grpc-load-balancing-on-kubernetes-without-tears/
This change allows to set collector service type to headless. We use it in production without problems.

[naseemkullah]

Thanks!

Left one suggestion to wrap the rendered value around an if statement.

Also please add the value in the REAME's values table.

[pavelnikolov]

@spacentropy are you planning to add the if statement that @naseemkullah has suggested above?

[spacentropy]

Hi. Sorry for the Loooooong delay. I've rebased the branch and applied the suggested changes.

Thanks!

[spacentropy]

Hi! Let's return to this. I've made the requested changes. Can we proceed to merging this? @pavelnikolov

[spacentropy]

@pavelnikolov Thanks for the approval! Can you please merge? I've rebased & signed commits.

[indreek]

@pavelnikolov Why did you remove loadBalancerIP field? If I plan to run only one instance of collector, i don't need Linkerd in front. It would be fully customizable if you wish to use k8s lb.

{{- if and (eq .Values.collector.service.type "LoadBalancer") .Values.collector.service.loadBalancerIP }}
  loadBalancerIP: {{ .Values.collector.service.loadBalancerIP }}
{{- end -}}