the server is currently unable to handle the request (get nodes.metrics.k8s.io)

在部署metrics server後，pod啓動成功，但是使用kubectl top node命令時，顯示報錯：
Error from server (ServiceUnavailable): the server is currently unable to handle the request (get nodes.metrics.k8s.io)
多方查看後，發現在master節點上ping不同metrics server的podIP。兩天的排錯，才發現是使用calico網絡bgp模式後，不同網段之間通信，pod不通
這裏重新生成calico的ippool，使用calico網絡的crosssubnet網絡實現

# 1、備份當前的ippool
calicoctl get ippool -o yaml > pool_bak.yaml
# 2、修改pool_bak.yaml
#----在  natOutgoing: true後面添加一行，關閉該ippool
    disabled: true
# 3、應用使生效
calicoctl apply -f pool_bak.yaml
# 4、查看ippool
calicoctl get ippool -o wide
# ***如下顯示
# --NAME                  CIDR           NAT    IPIPMODE      DISABLED   
# default-ipv4-ippool   10.66.0.0/16    true      Never        true      
# ****
# 5、刪除舊的ippool
calicoctl delete pool default-ipv4-ippool
# 6、新建新的ippool
calicoctl create -f -<<EOF
apiVersion: projectcalico.org/v3
kind: IPPool
metadata:
  name: new-pool
spec:
  cidr: 10.67.0.0/16
  ipipMode: CrossSubnet
  natOutgoing: true
EOF
# 7、查看新的ippool
# NAME       CIDR           NAT    IPIPMODE      DISABLED   
# new-pool   10.66.0.0/16   true   CrossSubnet   false   

然後將metrics server等pods重新生成，就可以解決問題啦

BINGO
BINGO
BINGO
BINGO