add dns items for coredns

# $(kubectl get cm coredns -n kube-system  -o json | jq .data.Corefile |grep -o host）

function add_coredns_host(){
CM=${CM:-coredns}
 
kubectl get cm $CM -n kube-system  -o json | jq .data.Corefile |grep -o hosts
ret=$?

if [[ $ret != 0 ]]; then
  # str=`kubectl get cm $CM -n kube-system -o json | jq .data.Corefile |   #      sed -e ‘0,/prometheus/s/prometheus/hosts {\\\n ‘"$item"‘\\\n }\\\n /‘`
  str=$(kubectl get cm $CM -n kube-system -o json | jq .data.Corefile |
           sed -e ‘0,/prometheus/s/prometheus/hosts {\\n       ‘"$1"‘\\n    }\\n    prometheus/‘)
else
  str=$(kubectl get cm $CM -n kube-system -o json | jq .data.Corefile |
           sed -e ‘s/\(hosts {\)/\1\\n       ‘"$1"‘/‘)
fi

NATPATH="/data/Corefile"
kubectl patch cm $CM -n kube-system --type=‘json‘ -p ‘[
{"op":"replace","path":"‘"$NATPATH"‘","value": ‘"$str"‘},
]‘
}


item="172.16.30.4 gateway.sdwam.opennes"
add_coredns_host  "$item"

# $(kubectl get cm coredns -n kube-system  -o json | jq .data.Corefile |grep -o host）

function add_coredns_host(){
CM=${CM:-coredns}

item=fallthrough

kubectl get cm $CM -n kube-system  -o json | jq .data.Corefile |grep -o hosts
ret=$?
if [[ $ret != 0 ]]; then
  # str=`kubectl get cm $CM -n kube-system -o json | jq .data.Corefile |   #      sed -e ‘0,/prometheus/s/prometheus/hosts {\\\n ‘"$item"‘\\\n }\\\n /‘`
  # str=$(kubectl get cm $CM -n kube-system -o json | jq .data.Corefile |
  #          sed -e ‘0,/prometheus/s/prometheus/hosts {\\n       ‘"$1"‘\\n    }\\n    prometheus/‘)
  str=$(kubectl get cm $CM -n kube-system -o json | jq .data.Corefile |
           sed -e ‘0,/prometheus/s/prometheus/hosts {\\n       ‘"$item"‘\\n    }\\n    prometheus/‘)
fi

NATPATH="/data/Corefile"
kubectl patch cm $CM -n kube-system --type=‘json‘ -p ‘[
{"op":"replace","path":"‘"$NATPATH"‘","value": ‘"$str"‘},
]‘

  str=$(kubectl get cm $CM -n kube-system -o json | jq .data.Corefile |
           sed -e ‘s/\(hosts {\)/\1\\n       ‘"$1"‘/‘)


NATPATH="/data/Corefile"
kubectl patch cm $CM -n kube-system --type=‘json‘ -p ‘[
{"op":"replace","path":"‘"$NATPATH"‘","value": ‘"$str"‘},
]‘
}


item="172.16.30.4 gateway.sdwam.opennes"
add_coredns_host  "$item"

kubectl scale deployment coredns -n kube-system --replicas=0
watch -n 1 "kubectl -n kube-system get pod |grep core"


kubectl scale deployment coredns -n kube-system --replicas=2  
watch -n 1 "kubectl -n kube-system get pod |grep core"