进城务工人员小梅Kubernetes中有几个port容易混淆。
一、Deployment的containerPort
首先是最常见containerPort，以官网文档https://kubernetes.io/docs/concepts/services-networking/connect-applications-service为例：
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apiVersion: apps/v1 kind: Deployment metadata: name: my-nginx spec: selector: matchLabels: run: my-nginx replicas: 2 template: metadata: labels: run: my-nginx spec: containers: - name: my-nginx image: nginx ports: - containerPort: 80 |
官网的文档让我们感觉需要使用containerPort来指定暴露的端口，但实际上根据官网https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.20/#container-v1-core中的说明：
List of ports to expose from the container. Exposing a port here gives the system additional information about the network connections a container uses, but is primarily informational. Not specifying a port here DOES NOT prevent that port from being exposed. Any port which is listening on the default “0.0.0.0” address inside a container will be accessible from the network. Cannot be updated.
因此，containerPort与Dockerfile的EXPOSE指令都是文档性的。即使不在Kubernetes的Deployment配置中通过containerPort配置端口，我们仍然可以使用集群内的Pod IP访问到容器内绑定到0.0.0.0的端口。
二、Service的port和targetPort
When you use port and targetPort, it will forward service:port to container:targetPort.
Kubernetes中Service的port和targetPort
参考文档：
1、https://medium.com/faun/should-i-configure-the-ports-in-kubernetes-deployment-c6b3817e495
2、https://stackoverflow.com/questions/57556606/what-is-the-relationship-between-expose-in-the-dockerfile-and-targetport-in-the
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