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Placement of Ingress Pods
Voyager has rich support for how HAProxy pods are placed on cluster nodes. Please check here to understand Kubernetes’ support for pod placement.
Before You Begin
At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikube.
Now, install Voyager operator in your minikube cluster following the steps here.
minikube start
# install without RBAC
curl -fsSL https://raw.githubusercontent.com/appscode/voyager/6.0.0/hack/deploy/voyager.sh \
| bash -s -- minikube
To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial. Run the following command to prepare your cluster for this tutorial:
$ curl -fSsL https://raw.githubusercontent.com/appscode/voyager/6.0.0/docs/examples/ingress/pod-placement/deploy-servers.sh | bash
+ kubectl create namespace demo
namespace "demo" created
+ kubectl run nginx --image=nginx --namespace=demo
deployment "nginx" created
+ kubectl expose deployment nginx --name=web --namespace=demo --port=80 --target-port=80
service "web" exposed
+ kubectl run echoserver --image=gcr.io/google_containers/echoserver:1.4 --namespace=demo
deployment "echoserver" created
+ kubectl expose deployment echoserver --name=rest --namespace=demo --port=80 --target-port=8080
service "rest" exposed
Using Node Selector
Node selectors can be used assign HAProxy ingress pods to specific nodes. Below is an example where ingress pods are run on node with nameminikube.
kubectl apply -f https://raw.githubusercontent.com/appscode/voyager/6.0.0/docs/examples/ingress/pod-placement/ingress-w-node-selector.yaml
apiVersion: voyager.appscode.com/v1beta1
kind: Ingress
metadata:
name: ingress-w-node-selector
namespace: demo
annotations:
ingress.appscode.com/type: NodePort
ingress.appscode.com/use-node-port: 'true'
ingress.appscode.com/replicas: '2'
spec:
nodeSelector:
kubernetes.io/hostname: minikube
rules:
- http:
paths:
- path: /
backend:
serviceName: rest
servicePort: 80
- path: /web
backend:
serviceName: web
servicePort: 80
Using Pod Anti-affinity
Affinity rules can be used assign HAProxy ingress pods to specific nodes or ensure that 2 separate HAProxy ingress pods are not placed on same node. Affinity rules are set via spec.affinity field in Voyager Ingress CRD. Below is an example where ingress pods are spread over run on node with nameminikube.
kubectl apply -f https://raw.githubusercontent.com/appscode/voyager/6.0.0/docs/examples/ingress/pod-placement/ingress-w-pod-anti-affinity.yaml
apiVersion: voyager.appscode.com/v1beta1
kind: Ingress
metadata:
name: ingress-w-pod-anti-affinity
namespace: demo
annotations:
ingress.appscode.com/type: NodePort
ingress.appscode.com/use-node-port: 'true'
ingress.appscode.com/replicas: '2'
spec:
rules:
- http:
paths:
- path: /
backend:
serviceName: rest
servicePort: 80
- path: /web
backend:
serviceName: web
servicePort: 80
affinity:
podAntiAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
- labelSelector:
matchExpressions:
- key: origin
operator: In
values:
- voyager
- key: origin-name
operator: In
values:
- voyager-ingress-w-pod-anti-affinity
topologyKey: 'kubernetes.io/hostname'
Using Taints and Toleration
Using taints and toleration, you can run voyager pods on dedicated nodes.
# taint nodes where only HAProxy ingress pods will run
kubectl taint nodes minikube IngressOnly=true:NoSchedule
kubectl apply -f https://raw.githubusercontent.com/appscode/voyager/6.0.0/docs/examples/ingress/pod-placement/ingress-w-toleration.yaml
apiVersion: voyager.appscode.com/v1beta1
kind: Ingress
metadata:
name: ingress-w-toleration
namespace: demo
annotations:
ingress.appscode.com/type: NodePort
ingress.appscode.com/use-node-port: 'true'
ingress.appscode.com/replicas: '2'
spec:
rules:
- http:
paths:
- path: /
backend:
serviceName: rest
servicePort: 80
- path: /web
backend:
serviceName: web
servicePort: 80
tolerations:
- key: IngressOnly
operator: Equal
value: 'true'
effect: NoSchedule
You can use these various option in combination with each other to achieve desired result. Say, you want to run your HAProxy pods on master instances. This can be done using an Ingress like below:
apiVersion: voyager.appscode.com/v1beta1
kind: Ingress
metadata:
name: ingress-w-node-selector
namespace: demo
annotations:
ingress.appscode.com/type: NodePort
ingress.appscode.com/use-node-port: 'true'
ingress.appscode.com/replicas: '2'
spec:
nodeSelector:
node-role.kubernetes.io/master: ""
rules:
- http:
paths:
- path: /
backend:
serviceName: rest
servicePort: 80
- path: /web
backend:
serviceName: web
servicePort: 80
tolerations:
- effect: NoSchedule
key: node-role.kubernetes.io/master
operator: Exists