I have a api-service with type 'ClusterIp' which is working fine and is accessible on the node with clusterip. I want to access it externally . It's a baremetal installation with kubeadm . I cannot use Loadbalancer or Nodeport.
If I use nginx-ingress that too I will use as 'ClusterIP' so how to get the service externally accessible in either api service or nginx-ingress case .
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
api ClusterIP 10.97.48.17 <none> 80/TCP 41s
ingress-nginx ClusterIP 10.107.76.178 <none> 80/TCP 3h49mChanges to solve the issue:
in /etc/nginx/sites-available
upstream backend {
server node1:8001;
server node2:8001;
server node3:8001;
}
server_name _;
location / {
proxy_pass http://backend;
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
try_files $uri $uri/ =404;
}
Well, as you can guess by reading the name, ClusterIp is only accessible from inside the cluster.
To make a service accessible from outside the cluster, you havec 3 options :
NodePort Service typeLoadBalancer Service type (you still have to manage your LoadBalancer manually though)There is a fourth option which is hostPort (which is not a service type) but I'd rather keep it from special case when you're absolutely sure that your pod will always be located on the same node (or eventually for debug).
Having this said, then this leaves us only with one solution offered by Kubernetes : Ingress.
ClusterIP services are accesible only within the cluster.
For bare metal clusters, you can use any of the following approaches to make a service available externally. Suggestions are from most recommended to least recommended order:
Use metallb to implement LoadBalancer service type support - https://metallb.universe.tf/. You will need a pool of IP addresses for metallb to handout. It also supports IP sharing mode where you can use same IP for multiple LoadBalancer services.
Use NodePort service. You can access your service from any node IP:node_port address. NodePort service selects random port in node port range by default. You can choose a custom port in node port range using spec.ports.nodePort field in the service specification.
Disadvantage: The node port range by default is 30000-32767. So you cannot bind to any custom port that you want like 8080. Although you can change the node port range with --service-node-port-range flag of kube-api-server, it is not recommended to use it with low port ranges.
Use hostPort to bind a port on the node.
Disadvantage: You don't have fixed IP address because you don't know which node your pod gets scheduled to unless you use nodeAffinity. You can make your pod a daemonset if you want it to be accessible from all nodes on the given port.
If you are dealing with HTTP traffic, another option is installing an IngressController like nginx or Traefik and use Ingress resource. As part of their installation, they use one of the approaches mentioned above to make themselves available externally.