Service and Ingress

Service is for East-West Traffic, Ingress is for North-South Traffic

Service is used for communication among different microservices

Endpoints manage and maintain pointed IP

service.png

Service Configuration

apiVersion: v1
kind: Service
metadata:
  name: nginx-svc
  labels:
    app: nginx-svc
spec:
  ports:
    - name: http # Name of the service port configuration
      protocol: TCP # Protocol used for port binding, supports TCP, UDP, SCTP; defaults to TCP
      port: 80 # The service's port
      targetPort: 9527 # The target pod's port
    - name: https
      port: 443
      protocol: TCP
      targetPort: 443
  selector: # Select which pods the current service will match and proxy traffic to
    app: nginx

Create the service

kubectl create -f nginx-svc.yaml

View service information, access via service's cluster IP

kubectl get svc

View pod information, access via pod's IP

kubectl get po -o wide

Create other pods and access via service name (recommended)

kubectl exec -it busybox -- sh
curl http://nginx-svc

By default, access within the current namespace. If you need to access a pod across namespaces, add ".namespace" after the service name

curl http://nginx-svc.default

Use the service to access external services from the cluster

Reduce redundant configurations

Implementation Method:

Write the service configuration file without specifying the selector property.

Manually create the Endpoint.

endpoint Config：

apiVersion: v1
kind: Endpoints
metadata:
labels:
app: wolfcode-svc-external # same as service
name: wolfcode-svc-external # same as service
namespace: default # same as service
subsets:
- addresses:
    - ip: <target ip> 
      ports: #  same as service
    - name: http # same as service
      port: 80
      protocol: TCP

If you want to visit the domain rather than IP address

apiVersion: v1
kind: Service
metadata:
  labels:
    app: wolfcode-external-domain
  name: wolfcode-external-domain
spec:
  type: ExternalName
  externalName: www.wolfcode.cn

Info

Type

1. ClusterIP: Can only be used within the cluster. If no type is specified, it defaults to ClusterIP.
2. ExternalName: Returns a CNAME alias defined in the configuration, which can be configured as a domain name.
3. LoadBalancer: Uses the load balancer service provided by the cloud service provider.

Ingress

Ingress.png

Similar as NGINX, can be understood as an abstraction of NGINX (NGINX is one implementation of Ingress)

Download ingress controller https://kubernetes.io/docs/concepts/services-networking/ingress/

Download helm，a package manager in k8s，simliar to java/maven

helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx

helm repo list

helm search repo ingress-nginx

helm pull ingress-nginx/ingress-nginx

tar xf ingress-nginx-xxx.tgz

cd ingress-nginx

Configuration of multiple name

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: wolfcode-nginx-ingress
  annotations:
    kubernetes.io/ingress.class: "nginx"  # Specifies the ingress controller to use (nginx in this case)
    nginx.ingress.kubernetes.io/rewrite-target: /  # Rewrites the URL to the root path before forwarding to the backend service
spec:
  rules:
    - host: k8s.wolfcode.cn
      http:
        paths:
          - pathType: Prefix  # Path type for matching (Prefix matches URL paths that start with '/api')
            backend:
              service:
                name: nginx-svc
                port:
                  number: 80
            path: /api  # URL path that the rule applies to
          - pathType: Exec  # Custom path type for executing actions
            backend:
              service:
                name: nginx-svc
                port:
                  number: 80
            path: /  # URL path that the rule applies to
    - host: api.wolfcode.cn
      http:
        paths:
          - pathType: Prefix  # Path type for matching (Prefix matches URL paths that start with '/')
            backend:
              service:
                name: nginx-svc
                port:
                  number: 80
            path: /  # URL path that the rule applies to