Kubernetes：如何公开多个微服务？

Question

i have a handful of dockerized microservices, each is listening for http requests on a certain port, and i have these deployments formalized as kubernetes yaml files

however, i can't figure out a working strategy to expose my deployments on the interwebs (in terms of kubernetes services)

each deployment has multiple replicas, and so i assume each deployment should have a matching load balancer service to expose it to the outside

now i can't figure out a strategy to sanely expose these microservices to the internet... here's what i'm thinking:

1. the whole cluster is exposed on a domain name, and services are subdomains

   • say the cluster is available at k8s.mydomain.com
   • each loadbalancer service (which exposes a corresponding microservice) should be accessible by a subdomain
     • auth-server.k8s.mydomain.com
     • profile-server.k8s.mydomain.com
     • questions-board.k8s.mydomain.com
     • so requests to each subdomain would be load balanced to the replicas of the matching deployment
   • so how do i actually achieve this setup? is this desirable?
     • can i expose each load balancer as a subdomain? is this done automatically?
     • or do i need an ingress controller?
     • am i barking up the wrong tree?
     • i'm looking for general advice on how to expose a single app which is a mosaic of microservices

2. each service is exposed on the same ip/domain, but each gets its own port

   • perhaps the whole cluster is accessible at k8s.mydomain.com again
   • can i map each port to a different load balancer?
     • k8s.mydomain.com:8000 maps to auth-server-loadbalancer
     • k8s.mydomain.com:8001 maps to profile-server-loadbalancer
   • is this possible? it seems less robust and less desirable than strategy 1 above

3. each service is exposed on its own ip/domain?

   • perhaps each service specifies a static ip, and my domain has A records pointing each subdomain at each of these ip's in a manual way?
   • how do i know which static ip's to use? in production? in local dev?

maybe i'm conceptualizing this wrong? can a whole kubernetes cluster map to one ip/domain?

what's the simplest way to expose a bunch of microservies in kubernetes? on the other hand, what's the most robust/ideal way to expose microservices in production? do i need a different strategy for local development in minikube? (i was just going to edit /etc/hosts a lot)

thanks for any advice, cheers

Answer 1

The first method is typically the format that everyone follows ie each microservice gets its own subdomain. You can achieve the same using Kubernetes ingress (for example Nginx Ingress https://kubernetes.github.io/ingress-nginx/ )

They need not be in the same domain also ie you can have both *.example.com and *.example2.com

The second method doesn't scale up as you would have a limited number of available ports and running on non-standard ports comes with its own issues.

Answer 2

Use an ingress:

https://kubernetes.io/docs/concepts/services-networking/ingress/#types-of-ingress

With an ingress, you can assign subdomains to different services, or you can serve all the services under different context roots with some url rewriting.

I don't suggest exposing services using different ports. Nonstandard ports have other problems.

Answer 3

I think the first option is by far the best.

Your Ingress might look like this:

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: name-virtual-host-ingress
spec:
  rules:
  - host: auth-server.k8s.mydomain.com
    http:
      paths:
      - backend:
          serviceName: service1
          servicePort: 80
  - host: profile-server.k8s.mydomain.com
    http:
      paths:
      - backend:
          serviceName: service2
          servicePort: 80

  - host: questions-board.k8s.mydomain.com
    http:
      paths:
      - backend:
          serviceName: service3
          servicePort: 80

You can read more about it on Kubernetes docs regardingIngress and Name based virtual hosting .

You can also use many Ingress Controllers depending where you will end up setting your cluster. You mentioned that you will be testing this on Minikube so I think nginx ingress will be a good choice here.

If you are thinking about managing your traffic you could consider istio .

Here is a nice guide Setting up HTTP(S) Load Balancing with Ingress and another once Configuring Domain Names with Static IP Addresses .