kubernetes（四）二进制安装-flannel安装

部署 flannel 网络(在master节点上执行）

kubernetes组件kubelet服务依赖docker服务，docker网络需要用flannel来配置docker0网桥的ip地址，所以需要先安装flannel网络组建

flannel 使用 vxlan 技术为各节点创建一个可以互通的 Pod 网络，使用的端口为 UDP 8472（需要开放该端口，如公有云 AWS 等）。

flanneld 第一次启动时，从 etcd 获取配置的 Pod 网段信息，为本节点分配一个未使用的地址段，然后创建 flannedl.1 网络接口（也可能是其它名称，如 flannel1 等）。

flannel 将分配给自己的 Pod 网段信息写入 /run/flannel/docker 文件，docker 后续使用这个文件中的环境变量设置 docker0 网桥，从而从这个地址段为本节点的所有 Pod 容器分配 IP

1. 下载和安装flanneld 二进制文件

   
   cd /opt/k8s/work
   mkdir flannel
   wget https://github.com/coreos/flannel/releases/download/v0.11.0/flannel-v0.11.0-linux-amd64.tar.gz
   tar -xzvf flannel-v0.11.0-linux-amd64.tar.gz -C flannel
   
   cp flannel/{flanneld,mk-docker-opts.sh} /opt/k8s/bin/
   
   export node_ip=192.168.0.114
   scp flannel/{flanneld,mk-docker-opts.sh} root@${192.168.0.114}:/opt/k8s/bin/
   

2. 创建 flanneld 证书和私钥

   flanneld 从 etcd 集群存取网段分配信息，而 etcd 集群启用了双向 x509 证书认证，所以需要为 flanneld 生成证书和私钥。

   1. 创建证书签名请求

      cd /opt/k8s/work
      cat > flanneld-csr.json <

   2. 生成证书和私钥

      cfssl gencert -ca=/opt/k8s/work/ca.pem \
        -ca-key=/opt/k8s/work/ca-key.pem \
        -config=/opt/k8s/work/ca-config.json \
        -profile=kubernetes flanneld-csr.json | cfssljson -bare flanneld
      ls flanneld*pem
      

   3. 将生成的证书和私钥分发到所有节点

      cd /opt/k8s/work
      mkdir -p /etc/flanneld/cert
      cp flanneld*.pem /etc/flanneld/cert
      
      export node_ip=192.168.0.114
      ssh root@${node_ip} "mkdir -p /etc/flanneld/cert"
      scp flanneld*.pem root@${node_ip}:/etc/flanneld/cert
      
      

3. 向 etcd 写入集群 Pod 网段信息

   cd /opt/k8s/work
   
   export FLANNEL_ETCD_PREFIX="/kubernetes/network"
   export ETCD_ENDPOINTS="https://192.168.0.107:2379"
   
   etcdctl \
     --endpoints=${ETCD_ENDPOINTS} \
     --ca-file=/opt/k8s/work/ca.pem \
     --cert-file=/opt/k8s/work/flanneld.pem \
     --key-file=/opt/k8s/work/flanneld-key.pem \
     mk ${FLANNEL_ETCD_PREFIX}/config '{"Network":"172.30.0.0/16", "SubnetLen": 24, "Backend": {"Type": "vxlan"}}'
   
   

   • 写入的 Pod 网段 Network 网络段对应的数值（如 /16）必须小于 SubnetLen对应的值（如24）

4. 创建 flanneld 服务的启动文件

   
   cd /opt/k8s/work
   export FLANNEL_ETCD_PREFIX="/kubernetes/network"
   export ETCD_ENDPOINTS="https://192.168.0.107:2379"
   
   cat > flanneld.service << EOF
   [Unit]
   Description=Flanneld overlay address etcd agent
   After=network.target
   After=network-online.target
   Wants=network-online.target
   After=etcd.service
   Before=docker.service
   
   [Service]
   Type=notify
   ExecStart=/opt/k8s/bin/flanneld \\
     -etcd-cafile=/etc/kubernetes/cert/ca.pem \\
     -etcd-certfile=/etc/flanneld/cert/flanneld.pem \\
     -etcd-keyfile=/etc/flanneld/cert/flanneld-key.pem \\
     -etcd-endpoints=${ETCD_ENDPOINTS} \\
     -etcd-prefix=${FLANNEL_ETCD_PREFIX} \\
     -ip-masq
   ExecStartPost=/opt/k8s/bin/mk-docker-opts.sh -k DOCKER_NETWORK_OPTIONS -d /run/flannel/docker
   Restart=always
   RestartSec=5
   StartLimitInterval=0
   
   [Install]
   WantedBy=multi-user.target
   RequiredBy=docker.service
   EOF
   
   

   • mk-docker-opts.sh 脚本将分配给 flanneld 的 Pod 子网段信息，通过-d参数写入 /run/flannel/docker 文件，后续 docker 启动时使用这个文件中的环境变量配置 docker0 网桥， -k 参数控制生成文件中变量的名称，下面docker启动时会用到这个变量；
   • flanneld 使用系统缺省路由所在的接口与其它节点通信，对于有多个网络接口（如内网和公网）的节点，可以用 -iface 参数指定通信接口;
   • -ip-masq: flanneld 为访问 Pod 网络外的流量设置 SNAT 规则，同时将传递给 Docker 的变量 --ip-masq（/run/flannel/docker 文件中）设置为 false，这样 Docker 将不再创建 SNAT 规则； Docker 的 --ip-masq 为 true 时，创建的 SNAT 规则比较“暴力”：将所有本节点 Pod 发起的、访问非 docker0 接口的请求做 SNAT，这样访问其他节点 Pod 的请求来源 IP 会被设置为 flannel.1 接口的 IP，导致目的 Pod 看不到真实的来源 Pod IP。 flanneld 创建的 SNAT 规则比较温和，只对访问非 Pod 网段的请求做 SNAT

5. 分发flanneld服务

   cd /opt/k8s/work
   
   cp flanneld.service /etc/systemd/system/
   
   export node_ip=192.168.0.114
   scp flanneld.service root@${node_ip}:/etc/systemd/system/
   
   

6. 启动flanneld服务

   systemctl daemon-reload && systemctl enable flanneld && systemctl restart flanneld
   
   ssh root@${node_ip) "systemctl daemon-reload && systemctl enable flanneld && systemctl restart flanneld"
   
   

7. 检查启动结果

   systemctl status flanneld|grep Active
   
   export node_ip=192.168.0.114
   ssh root@${node_ip} "systemctl status flanneld|grep Active"
   

   • 确保状态为 active (running)，否则查看日志，确认原因

   • 如果出现异常，通过如下命令查看

     journalctl -u flanneld
     

8. 检查分配给各 flanneld 的 Pod 网段信息

   export FLANNEL_ETCD_PREFIX="/kubernetes/network"
   export ETCD_ENDPOINTS="https://192.168.0.107:2379"
   
   
   etcdctl \
     --endpoints=${ETCD_ENDPOINTS} \
     --ca-file=/etc/kubernetes/cert/ca.pem \
     --cert-file=/etc/flanneld/cert/flanneld.pem \
     --key-file=/etc/flanneld/cert/flanneld-key.pem \
     get ${FLANNEL_ETCD_PREFIX}/config
   

   输出结果

   {"Network":"172.30.0.0/16", "SubnetLen": 24, "Backend": {"Type": "vxlan"}}
   

9. 查看已分配的 Pod 子网段列表

   export FLANNEL_ETCD_PREFIX="/kubernetes/network"
   export ETCD_ENDPOINTS="https://192.168.0.107:2379"
   
   etcdctl \
     --endpoints=${ETCD_ENDPOINTS} \
     --ca-file=/etc/kubernetes/cert/ca.pem \
     --cert-file=/etc/flanneld/cert/flanneld.pem \
     --key-file=/etc/flanneld/cert/flanneld-key.pem \
     ls ${FLANNEL_ETCD_PREFIX}/subnets
   

   输出结果

   /kubernetes/network/subnets/172.30.22.0-24
   /kubernetes/network/subnets/172.30.78.0-24
   

10. 检查节点 flannel 网络信息

    root@master:/opt/k8s/work# ip addr show
    1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
        link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
        inet 127.0.0.1/8 scope host lo
           valid_lft forever preferred_lft forever
        inet6 ::1/128 scope host
           valid_lft forever preferred_lft forever
    2: enp2s0:  mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
        link/ether 04:92:26:13:92:2b brd ff:ff:ff:ff:ff:ff
    3: wlp3s0:  mtu 1500 qdisc noqueue state UP group default qlen 1000
        link/ether d0:c5:d3:57:73:01 brd ff:ff:ff:ff:ff:ff
        inet 192.168.0.107/24 brd 192.168.0.255 scope global dynamic noprefixroute wlp3s0
           valid_lft 6385sec preferred_lft 6385sec
        inet6 fe80::1fda:e90a:207a:67e4/64 scope link noprefixroute
           valid_lft forever preferred_lft forever
    4: flannel.1:  mtu 1450 qdisc noqueue state UNKNOWN group default
        link/ether 12:cb:66:43:de:36 brd ff:ff:ff:ff:ff:ff
        inet 172.30.22.0/32 scope global flannel.1
           valid_lft forever preferred_lft forever
        inet6 fe80::10cb:66ff:fe43:de36/64 scope link
           valid_lft forever preferred_lft forever
      
    root@master:/opt/k8s/work# ip route show |grep flannel.1
    172.30.78.0/24 via 172.30.78.0 dev flannel.1 onlink 
    
    

11. 验证各节点能通过 Pod 网段互通

    root@master:/opt/k8s/work# ip addr show flannel.1 |grep -w inet
        inet 172.30.22.0/32 scope global flannel.1
    root@master:/opt/k8s/work# ssh 192.168.0.114 "/sbin/ip addr show flannel.1|grep -w inet"
        inet 172.30.78.0/32 scope global flannel.1
    root@master:/opt/k8s/work# ping -c 1 172.30.78.0
    PING 172.30.78.0 (172.30.78.0) 56(84) bytes of data.
    64 bytes from 172.30.78.0: icmp_seq=1 ttl=64 time=80.7 ms
    
    --- 172.30.78.0 ping statistics ---
    1 packets transmitted, 1 received, 0% packet loss, time 0ms
    rtt min/avg/max/mdev = 80.707/80.707/80.707/0.000 ms
    root@master:/opt/k8s/work# ssh 192.168.0.114 "ping -c 1 172.30.22.0"
    PING 172.30.22.0 (172.30.22.0) 56(84) bytes of data.
    64 bytes from 172.30.22.0: icmp_seq=1 ttl=64 time=4.09 ms
    
    --- 172.30.22.0 ping statistics ---
    1 packets transmitted, 1 received, 0% packet loss, time 0ms
    rtt min/avg/max/mdev = 4.094/4.094/4.094/0.000 ms
    
    
    

12. 生成文件内容，注意DOCKER_NETWORK_OPTIONS的值

    root@master:/opt/k8s/work# cat /run/flannel/subnet.env
    FLANNEL_NETWORK=172.30.0.0/16
    FLANNEL_SUBNET=172.30.22.1/24
    FLANNEL_MTU=1450
    FLANNEL_IPMASQ=true
    root@master:/opt/k8s/work# cat /run/flannel/docker
    DOCKER_OPT_BIP="--bip=172.30.22.1/24"
    DOCKER_OPT_IPMASQ="--ip-masq=false"
    DOCKER_OPT_MTU="--mtu=1450"
    DOCKER_NETWORK_OPTIONS=" --bip=172.30.22.1/24 --ip-masq=false --mtu=1450"