kubernetes（四）二进制安装-flannel安装

时间 2020-03-30

标签 kubernetes 二进制安装 flannel 繁體版

原文原文链接

部署 flannel 网络(在master节点上执行）

kubernetes组件kubelet服务依赖docker服务，docker网络须要用flannel来配置docker0网桥的ip地址，因此须要先安装flannel网络组建node

flannel 使用 vxlan 技术为各节点建立一个能够互通的 Pod 网络，使用的端口为 UDP 8472（须要开放该端口，如公有云 AWS 等）。linux

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，而后建立 flannedl.1 网络接口（也多是其它名称，如 flannel1 等）。git

flannel 将分配给本身的 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全部 Pod 容器分配 IPgithub

下载和安装flanneld 二进制文件docker

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/

建立 flanneld 证书和私钥json

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，因此须要为 flanneld 生成证书和私钥。网络

建立证书签名请求ssh

cd /opt/k8s/work
cat > flanneld-csr.json <<EOF
{
  "CN": "flanneld",
  "hosts": [],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "CN",
      "ST": "NanJing",
      "L": "NanJing",
      "O": "k8s",
      "OU": "system"
    }
  ]
}
EOF

生成证书和私钥oop

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

将生成的证书和私钥分发到全部节点ui

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

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）

建立 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，经过-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讯，对于有多个网络接口（如内网和公网）的节点，能够用 -iface 参数指定通讯接口;
- -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 将再也不建立 SNAT 规则； Docker 的 --ip-masq 为 true 时，建立的 SNAT 规则比较“暴力”：将全部本节点 Pod 发起的、访问非 docker0 接口的请求作 SNAT，这样访问其余节点 Pod 的请求来源 IP 会被设置为 flannel.1 接口的 IP，致使目的 Pod 看不到真实的来源 Pod IP。 flanneld 建立的 SNAT 规则比较温和，只对访问非 Pod 网段的请求作 SNAT

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/

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"

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)，不然查看日志，确认缘由
若是出现异常，经过以下命令查看
```
journalctl -u flanneld
```

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"}}

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

检查节点 flannel 网络信息

root@master:/opt/k8s/work# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> 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: <NO-CARRIER,BROADCAST,MULTICAST,UP> 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: <BROADCAST,MULTICAST,UP,LOWER_UP> 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: <BROADCAST,MULTICAST,UP,LOWER_UP> 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

验证各节点能经过 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

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"