k8s中如何固定一个pod的IP地址？该集群网络插件是calico

1、首先查看calico的CIDR地址范围

[root@nccztsjb-node-17 ~]# calicoctl get ippool
NAME           CIDR            SELECTOR   
default-pool   172.23.0.0/16   all()

2、然后呢，在这个地址范围内，给pod选择一个固定的IP地址

比如：172.23.45.27

通过在pod中加入annotation来实现：

  annotations:
    "cni.projectcalico.org/ipAddrs": "[\"172.23.45.27\"]"

使用如下的yaml创建一个pod

apiVersion: apps/v1
kind: Deployment
metadata:
  name: pod-static-ip
  labels:
    app: pod-static-ip
spec:  
  selector:
    matchLabels:
      app: pod-static-ip
  template:  
    metadata:
      labels:
        app: pod-static-ip
      annotations:
        "cni.projectcalico.org/ipAddrs": "[\"172.23.45.27\"]"  
    spec:
      containers:
        - name: pod-static-ip
          image: 172.20.58.152/middleware/nginx:1.21.4

查看创建的pod的ip

[root@nccztsjb-node-01 ~]# kubectl get pod -o wide | grep static
pod-static-ip-75779bcc95-hxj7f   1/1     Running   0          10s   172.23.45.27   node177   <none>           <none>
[root@nccztsjb-node-01 ~]# 

确实是我们固定的IP地址172.23.45.27

3、重启一下，看pod的ip地址是否会变化

[root@nccztsjb-node-01 ~]# kubectl delete pod pod-static-ip-75779bcc95-hxj7f 
pod "pod-static-ip-75779bcc95-hxj7f" deleted
[root@nccztsjb-node-01 ~]# 
[root@nccztsjb-node-01 ~]# kubectl get pod -o wide | grep static
pod-static-ip-75779bcc95-7996b   1/1     Running   0          3s    172.23.45.27   node177   <none>           <none>
[root@nccztsjb-node-01 ~]# 

OK，重启pod之后，ip地址，还是没变，目的达成。