K8S 之 Flannel之SNAT規劃優化

一、Flannel之SNAT規劃優化作用

解決兩宿主機容器之間的透明訪問，如不進行優化，容器之間的訪問，日誌記錄爲宿主機的IP地址。

1、宿主機訪問172.7.22.2的nginx容器情況

2、172.7.22.2查看nginx訪問日誌

3、進入172.7.21.2的容器訪問172.7.22.2的nginx容器，查看日誌

4、再次查看172.7.22.2的nginx訪問日誌

5、解決問題：當容器172.7.21.2訪問172.7.22.2的nginx容器時，展示的日誌應爲172.7.21.2

二、解決方法

1、安裝iptables-services組件
[root@test-nodes1 ~]# yum -y install iptables-services
[root@test-nodes1 ~]# systemctl start iptables
[root@test-nodes1 ~]# systemctl enable iptables
Created symlink from /etc/systemd/system/basic.target.wants/iptables.service to /usr/lib/systemd/system/iptables.service.
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2、把以下iptable記錄的僞裝轉向刪除
[root@test-nodes1 ~]# iptables-save |grep -i postrouting
:POSTROUTING ACCEPT [68:4098]
:KUBE-POSTROUTING - [0:0]
-A POSTROUTING -m comment --comment "kubernetes postrouting rules" -j KUBE-POSTROUTING
-A POSTROUTING -s 172.7.21.0/24 ! -o docker0 -j MASQUERADE       #刪除此條
-A KUBE-POSTROUTING -m comment --comment "kubernetes service traffic requiring SNAT" -m mark --mark 0x4000/0x4000 -j MASQUERADE
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3、刪除該記錄
[root@test-nodes1 ~]# iptables -t nat -D POSTROUTING -s 172.7.21.0/24 ! -o docker0 -j MASQUERADE
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4、插入一條新的記錄（排除對172.7.0.0/16網絡訪問的僞裝）
[root@test-nodes1 ~]# iptables -t nat -I POSTROUTING -s 172.7.21.0/24 ! -d 172.7.0.0/16 ! -o docker0 -j MASQUERADE
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5、查看是否生效
[root@test-nodes1 ~]# iptables-save |grep -i postrouting
:POSTROUTING ACCEPT [13:814]
:KUBE-POSTROUTING - [0:0]
-A POSTROUTING -s 172.7.21.0/24 ! -d 172.7.0.0/16 ! -o docker0 -j MASQUERADE
-A POSTROUTING -m comment --comment "kubernetes postrouting rules" -j KUBE-POSTROUTING
-A KUBE-POSTROUTING -m comment --comment "kubernetes service traffic requiring SNAT" -m mark --mark 0x4000/0x4000 -j MASQUERADE
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6、刪除iptables上所有reject拒絕規則
[root@test-nodes1 ~]# iptables-save | grep -i reject
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
[root@test-nodes1 ~]# iptables -t filter -D INPUT -j REJECT --reject-with icmp-host-prohibited
[root@test-nodes1 ~]# iptables -t filter -D FORWARD -j REJECT --reject-with icmp-host-prohibited
[root@test-nodes1 ~]# iptables-save | grep -i reject
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7、保存iptables規則
[root@test-nodes1 ~]# iptables-save > /etc/sysconfig/iptables

三、驗證結果

1、通過容器172.7.21.2訪問172.7.22.2

2、查看172.7.22.2的容器日誌

備註：test-nodes需要有相同的操作