Minikube running in Docker, and port forwarding - docker

Question

I'm pretty well versed in Docker, but I haven't got Minikube/K8s working yet. I first tried setting up artifactory-oss in helm but failed to connect to the LoadBalancer. Now I'm just trying the basic hello-minikube NodePort setup as a sanity check.
When I do minikube start, it starts up minikube in Docker:
> docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ebabea521ffe gcr.io/k8s-minikube/kicbase:v0.0.18 "/usr/local/bin/entr…" 2 weeks ago Up 36 minutes 127.0.0.1:49167->22/tcp, 127.0.0.1:49166->2376/tcp, 127.0.0.1:49165->5000/tcp, 127.0.0.1:49164->8443/tcp, 127.0.0.1:49163->32443/tcp minikube
So Minikube only has ports 4916(3/4/5/6/7) open?
So I installed hello-minikube:
> kubectl create deployment hello-minikube --image=k8s.gcr.io/echoserver:1.4
> kubectl expose deployment hello-minikube --type=NodePort --port=8080
> minikube ip
192.168.49.2
> minikube service list
|----------------------|------------------------------------|--------------|---------------------------|
| NAMESPACE | NAME | TARGET PORT | URL |
|----------------------|------------------------------------|--------------|---------------------------|
| default | hello-minikube | 8080 | http://192.168.49.2:30652 |
| default | kubernetes | No node port |
| kube-system | ingress-nginx-controller-admission | No node port |
| kube-system | kube-dns | No node port |
| kubernetes-dashboard | dashboard-metrics-scraper | No node port |
| kubernetes-dashboard | kubernetes-dashboard | No node port |
|----------------------|------------------------------------|--------------|---------------------------|
> minikube service --url hello-minikube
http://192.168.49.2:30652
I check firewall, and it has the ports I've opened:
> sudo firewall-cmd --list-all
public (active)
target: default
icmp-block-inversion: no
interfaces: ens192
sources:
services: dhcpv6-client http https ssh
ports: 8000-9000/tcp 30000-35000/tcp
protocols:
masquerade: no
forward-ports:
source-ports:
icmp-blocks:
rich rules:
> kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-minikube-6ddfcc9757-hxxmf 1/1 Running 0 40m
> kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
hello-minikube NodePort 10.97.233.42 <none> 8080:30652/TCP 36m
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 19d
> kubectl describe services hello-minikube
Name: hello-minikube
Namespace: default
Labels: app=hello-minikube
Annotations: <none>
Selector: app=hello-minikube
Type: NodePort
IP Families: <none>
IP: 10.97.233.42
IPs: 10.97.233.42
Port: <unset> 8080/TCP
TargetPort: 8080/TCP
NodePort: <unset> 30652/TCP
Endpoints: 172.17.0.6:8080
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>
I've tried every IP and port combination, minikube tunnel, and kube proxy and a few other things but I just can't find any port to access this service from another machine. I can't get an 'External-IP'. nmap finds a bunch of ports if i search from the machine itself.
> nmap -p 1-65000 localhost
Starting Nmap 6.40 ( http://nmap.org ) at 2021-04-26 15:16 SAST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0013s latency).
Other addresses for localhost (not scanned): 127.0.0.1
Not shown: 64971 closed ports
PORT STATE SERVICE
22/tcp open ssh
25/tcp open smtp
80/tcp open http
111/tcp open rpcbind
443/tcp open https
631/tcp open ipp
3000/tcp open ppp
5000/tcp open upnp
5050/tcp open mmcc
8060/tcp open unknown
8080/tcp open http-proxy
8082/tcp open blackice-alerts
9090/tcp open zeus-admin
9093/tcp open unknown
9094/tcp open unknown
9100/tcp open jetdirect
9121/tcp open unknown
9168/tcp open unknown
9187/tcp open unknown
9229/tcp open unknown
9236/tcp open unknown
33757/tcp open unknown
35916/tcp open unknown
41266/tcp open unknown
49163/tcp open unknown
49164/tcp open unknown
49165/tcp open unknown
49166/tcp open unknown
49167/tcp open unknown
But if I scan that machine from another machine on the network:
> nmap -p 1-65000 10.20.2.26
Starting Nmap 6.40 ( http://nmap.org ) at 2021-04-26 15:23 SAST
Nmap scan report for 10.20.2.26
Host is up (0.00032s latency).
Not shown: 58995 filtered ports, 6001 closed ports
PORT STATE SERVICE
22/tcp open ssh
80/tcp open http
443/tcp open https
8060/tcp open unknown
those ports don't seem to be accessible. Any ideas?
-- EDIT 1:
The sys admin says only 10.20.x.x IPs will resolve. So 192.168.x.x and 10.96.x.x won't work. So perhaps this --service-cluster-ip-range field is what I'm looking for. I will try it out next.

Answer 1

I faced a similar issue that I was banging my head upon, this documentation was quite helpful. In my case I was accessing a Jenkins build server running in a Kubernetes cluster via minikube on my Mac OS.
I followed steps to get this port forwarding working:
Confirm the port of your pod :
kubectl get pod <podname-f5d-48kbr> --template='{{(index (index .spec.containers 0).ports 0).containerPort}}{{"\n"}}' -n <namespace-name>
Say the output displays
> 27013
Forward a local port to a port on the Pod like so :
kubectl port-forward <podname-deployment-f5db75f7-48kbr> 8080:27013 -n <namespace-name>
and that should start the port forwarding, the output like :
Forwarding from 127.0.0.1:8080 -> 27013
Forwarding from [::1]:8080 -> 27013
now access your application on the browser via http://localhost:8080/

Answer 2

Posted community wiki for better visibility. Feel free to expand it.
Based on this answer.
Seems there is no possibility to access minikube cluster setup with --driver=docker from the other host in the same local network.
The workaround is to use other driver while setting up minikube cluster:
--driver=virtualbox (recommended) -> use Bridged Adapter setting
--driver=none (potential issues)
For more details (how to setup etc.) please refer to this answer.