Couldn't access my Kubernetes service via a traefik reverse proxy - kubernetes

Question

I deploy a kubernetes cluster (1.8.8) in an cloud openstack pf (1 master with public ip adress/ 3 nodes). I want to use traefik (last version 1.6.1) as a reverse proxy for accessing my services.
Traefik was well deployed as a daemonset and I can access his GUI on port 8081. My prometheus ingress appears correctly in the traefik interface but I can't access my prometheus server UI.
Could you tell me what I am doing wrong ? Did I miss something ?
Thanks
Ingress of my prometheus:
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: prometheus-ingress
annotations:
kubernetes.io/ingress.class: traefik
traefik.frontend.rule.type: pathprefixstrip
spec:
rules:
- http:
paths:
- path: /prometheus
backend:
serviceName: prometheus-svc
servicePort: prom
My daemonset is below:
apiVersion: v1
kind: Namespace
metadata:
name: traefik
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: traefik-ingress-controller
namespace: traefik
---
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: traefik-ingress-controller
namespace: traefik
labels:
k8s-app: traefik-ingress-lb
kubernetes.io/cluster-service: "true"
spec:
template:
metadata:
labels:
k8s-app: traefik-ingress-lb
name: traefik-ingress-lb
spec:
hostNetwork: true # workaround
serviceAccountName: traefik-ingress-controller
terminationGracePeriodSeconds: 60
tolerations:
- key: node-role.kubernetes.io/master
effect: NoSchedule
containers:
- image: traefik:v1.6.1
name: traefik-ingress-lb
imagePullPolicy: Always
volumeMounts:
- mountPath: "/config"
name: "config"
resources:
requests:
cpu: 100m
memory: 20Mi
args:
- --kubernetes
- --configfile=/config/traefik.toml
volumes:
- name: config
configMap:
name: traefik-conf
---
apiVersion: v1
kind: Service
metadata:
name: traefik-web-ui
namespace: traefik
spec:
selector:
k8s-app: traefik-ingress-lb
ports:
- port: 80
targetPort: 8080
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: traefik-web-ui
namespace: traefik
annotations:
kubernetes.io/ingress.class: traefik
traefik.frontend.rule.type: pathprefixstrip
spec:
rules:
- host: example.com
http:
paths:
- backend:
serviceName: traefik-web-ui
servicePort: 80
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: traefik-ingress-controller
rules:
- apiGroups:
- ""
resources:
- services
- endpoints
- secrets
verbs:
- get
- list
- watch
- apiGroups:
- extensions
resources:
- ingresses
verbs:
- get
- list
- watch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: traefik-ingress-controller
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: traefik-ingress-controller
subjects:
- kind: ServiceAccount
name: traefik-ingress-controller
namespace: kube-system
---
apiVersion: v1
kind: ConfigMap
metadata:
name: traefik-conf
namespace: traefik
data:
traefik.toml: |-
defaultEntryPoints = ["http"]
[entryPoints]
[entryPoints.http]
address = ":80"
[web]
address = ":8081"