PowerFlex 4.x 如何更新 DNS 伺服器

1.從 MVM 節點執行下列命令，以檢視目前的 DNS 伺服器。

cat /etc/resolv.conf

delladmin@mvm1:~> cat /etc/resolv.conf
### /etc/resolv.conf is a symlink to /run/netconfig/resolv.conf
### autogenerated by netconfig!
#
# Before you change this file manually, consider to define the
# static DNS configuration using the following variables in the
# /etc/sysconfig/network/config file:
#     NETCONFIG_DNS_STATIC_SEARCHLIST
#     NETCONFIG_DNS_STATIC_SERVERS
#     NETCONFIG_DNS_FORWARDER
# or disable DNS configuration updates via netconfig by setting:
#     NETCONFIG_DNS_POLICY=''
#
# See also the netconfig(8) manual page and other documentation.
#
### Call "netconfig update -f" to force adjusting of /etc/resolv.conf.
search boston.ee.com
nameserver 1.2.3.4  <----

2.若要在 MVM 節點上新增/移除 DNS 伺服器，請編輯 /etc/sysconfig/network/config 檔案的NETCONFIG_DNS_STATIC_SERVERS區段。

在以下範例中，新增 DNS 伺服器 5.6.7.8。儲存檔案，並在進行必要的變更後退出。

sudo vi /etc/sysconfig/network/config

delladmin@mvm1:~> sudo vi /etc/sysconfig/network/config
...
## Type:        string
## Default:     ""
#
# List of DNS nameserver IP addresses to use for host-name lookup.
# When the NETCONFIG_DNS_FORWARDER variable is set to "resolver",
# the name servers are written directly to /etc/resolv.conf.
# Otherwise, the nameserver are written into a forwarder specific
# configuration file and the /etc/resolv.conf does not contain any
# nameservers causing the glibc to use the name server on the local
# machine (the forwarder). See also netconfig(8) manual page.
#
NETCONFIG_DNS_STATIC_SERVERS="1.2.3.4 5.6.7.8"  <----

3.執行下列命令，將變更推送至 /etc/resolv.conf：

sudo netconfig update -f

delladmin@mvm1:~> sudo netconfig update -f

4.確認已套用變更：

delladmin@mvm1:~> cat /etc/resolv.conf
 
### /etc/resolv.conf is a symlink to /run/netconfig/resolv.conf
### autogenerated by netconfig!
#
# Before you change this file manually, consider to define the
# static DNS configuration using the following variables in the
# /etc/sysconfig/network/config file:
#     NETCONFIG_DNS_STATIC_SEARCHLIST
#     NETCONFIG_DNS_STATIC_SERVERS
#     NETCONFIG_DNS_FORWARDER
# or disable DNS configuration updates via netconfig by setting:
#     NETCONFIG_DNS_POLICY=''
#
# See also the netconfig(8) manual page and other documentation.
#
### Call "netconfig update -f" to force adjusting of /etc/resolv.conf.
search boston.ee.com
nameserver 1.2.3.4
nameserver 5.6.7.8     <-----

5.在所有 MVM 節點上重複上述步驟。

6.刪除 coredns Pod 以將變更傳播到那些 Pod：

for x in `kubectl get pods -n kube-system| grep -i rke2-coredns-rke2-coredns | awk '{print $1}' | grep -iv auto`; do kubectl delete pods -n kube-system $x; done

7.確認 DNS 變更現在已反映在核心 Pod 中 （有兩個核心 Pod 負責 DNS）：

for x in `kubectl get pods -n kube-system|grep -i rke2-coredns-rke2-coredns|awk '{print $1}'|grep -iv auto`; do echo $x; kubectl exec -it $x -n kube-system -- cat /etc/resolv.conf; echo " "; done
 

rke2-coredns-rke2-coredns-6d6fb45d66-8t962
search boston.ee.com
nameserver 1.2.3.4
nameserver 5.6.7.8     <-----
 
rke2-coredns-rke2-coredns-6d6fb45d66-b5c8f
search boston.ee.com
nameserver 1.2.3.4
nameserver 5.6.7.8     <-----