I currently trying to create a cluster of X pods witch each have a personal persistent volume. To do that I've created a StateFulSet
with X replicas and a PersistentVolumeClaimTemplate
This part is working.
The problem is that it's seem's to be impossible to expose thoses pods with a LoadBalancer in the same way as a deployment
(because of the uniqueness of a pods in a statefulset).
At this moment I've tried to expose it as a simple deployment witch is not working and the only way I've found is to expose each pods one by one (I've not tested it but I saw it on this) but it's not that scalable...
I'm not running kubernetes on any cloud provider platform then please avoid exclusive command line.
The problem is that it's seem's to be impossible to expose thoses pods with a LoadBalancer in the same way as a deployment (because of the uniqueness of a pods in a statefulset).
Why not? Here is my StatefulSet with default Nginx
$ k -n test get statefulset
NAME DESIRED CURRENT AGE
web 2 2 5d
$ k -n test get pods
web-0 1/1 Running 0 5d
web-1 1/1 Running 0 5d
Here is my Service type LoadBalancer which is NodePort (in fact) in case of Minikube
$ k -n test get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
nginx LoadBalancer 10.110.22.74 <pending> 80:32710/TCP 5d
Let's run some pod with curl and do some requests to ClusterIP:
$ kubectl -n test run -i --tty tools --image=ellerbrock/alpine-bash-curl-ssl -- bash
bash-4.4$ curl 10.110.22.74 &> /dev/null
bash-4.4$ curl 10.110.22.74 &> /dev/null
bash-4.4$ curl 10.110.22.74 &> /dev/null
bash-4.4$ curl 10.110.22.74 &> /dev/null
Let's check out Nginx logs:
$ k -n test logs web-0
172.17.0.7 - - [18/Apr/2019:23:35:04 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.61.0"
172.17.0.7 - - [18/Apr/2019:23:35:05 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.61.0"
172.17.0.7 - - [18/Apr/2019:23:35:17 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.61.0"
$ k -n test logs web-1
172.17.0.7 - - [18/Apr/2019:23:35:15 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.61.0"
172.17.0.7 - is my pod with curl:
NAME READY STATUS RESTARTS AGE IP NODE
tools-654cfc5cdc-8zttt 1/1 Running 1 5d 172.17.0.7 minikube
Actually ClusterIP is totally enough in case of load balancing between StatefulSet's pods, because you have a list of Endpoints
$ k -n test get endpoints
NAME ENDPOINTS AGE
nginx 172.17.0.5:80,172.17.0.6:80 5d
YAMLs:
apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
name: web
spec:
serviceName: "nginx"
replicas: 2
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: k8s.gcr.io/nginx-slim:0.8
ports:
- containerPort: 80
name: web
apiVersion: v1
kind: Service
metadata:
name: nginx
labels:
app: nginx
spec:
type: LoadBalancer
ports:
- port: 80
name: web
selector:
app: nginx