Nginx Daemonset - How do I select which IP address to bind to? - docker

Question

I have a Docker Enterprise k8 bare metal cluster running on Centos8, and following the official docs to install NGINX using manifest files from GIT: https://docs.nginx.com/nginx-ingress-controller/installation/installation-with-manifests/
The pod seems to be running:
kubectl -n nginx-ingress describe pod nginx-ingress-fzr2j
Name: nginx-ingress-fzr2j
Namespace: nginx-ingress
Priority: 0
Node: server.example.com/172.16.1.180
Start Time: Sun, 16 Aug 2020 16:48:49 -0400
Labels: app=nginx-ingress
controller-revision-hash=85879fb7bc
pod-template-generation=2
Annotations: kubernetes.io/psp: privileged
Status: Running
IP: 192.168.225.27
IPs:
IP: 192.168.225.27
But my issue is the IP address it has selected is a 192.168.225.27. This is a second network on this server. How do I tell nginx to use the 172.16.1.180 address that is has in the Node: part?
The Daemset config is :
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: nginx-ingress
namespace: nginx-ingress
spec:
selector:
matchLabels:
app: nginx-ingress
template:
metadata:
labels:
app: nginx-ingress
#annotations:
#prometheus.io/scrape: "true"
#prometheus.io/port: "9113"
spec:
serviceAccountName: nginx-ingress
containers:
- image: nginx/nginx-ingress:edge
imagePullPolicy: Always
name: nginx-ingress
ports:
- name: http
containerPort: 80
hostPort: 80
- name: https
containerPort: 443
hostPort: 443
- name: readiness-port
containerPort: 8081
#- name: prometheus
#containerPort: 9113
readinessProbe:
httpGet:
path: /nginx-ready
port: readiness-port
periodSeconds: 1
securityContext:
allowPrivilegeEscalation: true
runAsUser: 101 #nginx
capabilities:
drop:
- ALL
add:
- NET_BIND_SERVICE
env:
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
args:
- -nginx-configmaps=$(POD_NAMESPACE)/nginx-config
- -default-server-tls-secret=$(POD_NAMESPACE)/default-server-secret
I can't see any configuration option for which IP address to bind to.

Answer 1

The thing you are likely looking for is hostNetwork: true, which:
Use the host's network namespace. If this option is set, the ports that will be used must be specified. Default to false
spec:
template:
spec:
hostNetwork: true
containers:
- image: nginx/nginx-ingress:edge
name: nginx-ingress
You would only then need to specify a bind address if it bothered you having the Ingress controller bound to all addresses on the host. If that's still a requirement, you can have the Node's IP injected via the valueFrom: mechanism:
...
containers:
- env:
- name: MY_NODE_IP
valueFrom:
fieldRef:
status.hostIP