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{
  "cniVersion": "0.3.1",
  "name": "mynet",
  "type": "myplugin",
  "ipam": {
    "type": "host-local",
    "subnet": "10.22.0.0/16",
    "routes": [{ "dst": "0.0.0.0/0" }]
  },
  "dns": {
    "nameservers": ["10.96.0.10"],
    "domain": "cluster.local"
  }
}

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{
  "type": "flannel",
  "delegate": {
    "type": "bridge",
    "ipam": { "type": "host-local", "subnet": "10.244.1.0/24" },
    "isDefaultGateway": true,
    "mtu": 1410
  }
}

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package main

import (
    "github.com/containernetworking/cni/pkg/skel"
    "github.com/containernetworking/cni/pkg/types"
    current "github.com/containernetworking/cni/pkg/types/100"
    "github.com/containernetworking/cni/pkg/version"
)

func cmdAdd(args *skel.CmdArgs) error {
    // 1. 解析 stdin JSON（Network Configuration）
    conf := &MyNetConf{}
    if err := json.Unmarshal(args.StdinData, conf); err != nil {
        return err
    }

    // 2. 进入 Pod Network Namespace
    podNS, _ := ns.GetNS(args.Netns)
    defer podNS.Close()

    // 3. 创建 veth pair
    hostVeth, containerVeth, _ := setupVeth(args.IfName, conf.MTU, podNS)

    // 4. 调 IPAM 插件分配 IP
    ipamResult, _ := ipam.ExecAdd(conf.IPAM.Type, args.StdinData)

    // 5. 在 Pod NS 内配置 IP
    podNS.Do(func(_ ns.NetNS) error {
        netlink.AddrAdd(containerVeth, ipamResult.IPs[0].Address)
        netlink.LinkSetUp(containerVeth)
        netlink.RouteAdd(&netlink.Route{Gw: ipamResult.IPs[0].Gateway})
        return nil
    })

    // 6. 在宿主机配置路由
    netlink.RouteAdd(&netlink.Route{
        LinkIndex: hostVeth.Attrs().Index,
        Dst:       &ipamResult.IPs[0].Address,
    })

    // 7. 返回结果
    result := &current.Result{
        CNIVersion: conf.CNIVersion,
        IPs:        ipamResult.IPs,
        DNS:        conf.DNS,
    }
    return types.PrintResult(result, conf.CNIVersion)
}

func cmdDel(args *skel.CmdArgs) error {
    // 1. 解析配置
    // 2. 调 IPAM 插件释放 IP
    // 3. 删除 veth pair
    // 4. 清理路由、iptables 规则
    return nil
}

func cmdCheck(args *skel.CmdArgs) error { return nil }

func main() {
    skel.PluginMain(cmdAdd, cmdCheck, cmdDel, version.All, "")
}

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func cmdDel(args *skel.CmdArgs) error {
    // 如果之前 ADD 时保存了配置缓存（/var/lib/cni/<plugin>/*.json），读取
    cachedConf := loadCachedConf(args.ContainerID)

    // 1. 调 IPAM 释放 IP
    ipam.ExecDel(cachedConf.IPAM.Type, args.StdinData)

    // 2. 删除 veth pair（删除任意一端，另一端自动清理）
    netlink.LinkDel(vethHost)

    // 3. 清理宿主机路由
    netlink.RouteDel(&route)

    // 4. 清理 iptables 规则（如果有）
    return nil
}

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# 1. 准备 CNI 配置文件
cat > /etc/cni/net.d/10-test.conflist << 'EOF'
{
  "cniVersion": "0.3.1",
  "name": "testnet",
  "type": "myplugin",
  "ipam": { "type": "host-local", "subnet": "10.30.0.0/24" }
}
EOF

# 2. 创建网络命名空间模拟 Pod
ip netns add testpod
CNI_PATH=/opt/cni/bin cnitool add testnet /var/run/netns/testpod

# 3. 验证
ip netns exec testpod ip addr
ip netns exec testpod ip route

# 4. 清理
CNI_PATH=/opt/cni/bin cnitool del testnet /var/run/netns/testpod
ip netns delete testpod