let’s start two pods so we can do the test
#minikube delete --all minikube start --driver=docker minikube addons enable metrics-server kubectl create deployment web --image=gcr.io/google-samples/hello-app:1.0 kubectl create deployment devuan --image=pbraun9/devuan kubectl get pods -o wide # notice IPs kubectl get svc # just k8s kubectl get endpoints # idem kubectl exec -ti devuan-57c996788d-fk9nd -- bash
the pods can talk to each other without a service (no DNS)
ping -c1 10.244.0.3 ping -c1 web curl 10.244.0.3:8080
==> IP responds but DNS doesn’t, micro-service is available anyhow
now let’s try to make ingress talk to the pods directly
minikube addons enable ingress kubectl get pods -n ingress-nginx
cat > ingress-next-step.yml <<EOF
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: ingress-next-step
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /$1
spec:
rules:
- host: hello-world.info
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: web
port:
number: 8080
EOF
kubectl apply -f ingress-next-step.yml
now let’s try
from within
kubectl get pods -o wide kubectl get pods -o wide -n ingress-nginx kubectl exec -ti ingress-nginx-controller-7799c6795f-qjm8t -n ingress-nginx -- bash
check
ping -c1 10.244.0.3 ping -c1 web curl 10.244.0.3:8080
from outside
curl --resolve hello-world.info:80:192.168.49.2 -i http://hello-world.info # NOK
==> doesn’t work because it goes through the service
kubectl get ingress ingress-next-step -o yaml
for ingress to work normally we absolutely need a service
kubectl expose deploy web --type=ClusterIP --port=8080 kubectl get endpoints
==> the endpoint got created and shows the true IP behind the service
https://stackoverflow.com/questions/58298889/can-a-pod-directly-call-another-pod
https://stackoverflow.com/questions/43941772/get-yaml-for-deployed-kubernetes-services
https://kubernetes.io/docs/concepts/services-networking/ingress/#resource-backend