Docker 配置Flannel网络过程及原理

flannel 安装

yum -y install flannel

flannel 配置

在etcd中创建变量

etcdctl --endpoint http://10.132.47.70:2379 set /flannel/network/config '{"Network":"10.0.0.0/16","SubnetLen":24,"Backend":{"Type":"vxlan","VNI":0}}'

创建flannel日志目录

mkdir -p /var/log/k8s/flannel/

配置flannel

vi /etc/sysconfig/flanneld

FLANNEL_ETCD_ENDPOINTS="http://10.132.47.70:2379,http://10.132.47.71:2379,http://10.132.47.72:2379"
FLANNEL_ETCD_PREFIX=“/flannel/network"
FLANNEL_OPTIONS="--logtostderr=false --log_dir=/var/log/k8s/flannel/ --etcd-endpoints=http://10.132.47.70:2379,http://10.132.47.71:2379,http://10.132.47.72:2379 --iface=eno16780032"

启动flannel

systemctl daemon-reload flanneld

systemctl restart flannel

systemctl enable flanneld

flannel启动过程解析

flannel服务需要先于docker启动。flannel服务启动时主要做了以下几步的工作：
从etcd中获取network的配置信息
划分subnet，并在etcd中进行注册
将子网信息记录到

/run/flannel/subnet.env

中

cat /run/flannel/subnet.env

FLANNEL_NETWORK=10.0.0.0/16
FLANNEL_SUBNET=10.0.53.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=false

之后将会有一个脚本将subnet.env转写成一个docker的环境变量文件

/run/flannel/docker

cat /run/flannel/docker

DOCKER_OPT_BIP="--bip=10.0.53.1/24"

DOCKER_OPT_IPMASQ="--ip-masq=true"
DOCKER_OPT_MTU="--mtu=1450"
DOCKER_NETWORK_OPTIONS=" --bip=10.0.53.1/24 --ip-masq=true --mtu=1450 "

 

配置docker

sysetmctl show docker 将会发现 在安装flannel后自动生成配置

DropInPaths=/usr/lib/systemd/system/docker.service.d/flannel.conf

并引用

/run/flannel/docker

故在docker的systemd文件中应用对应变量 DOCKER_NETWORK_OPTIONS 即可

 vi /etc/systemd/system/docker.service.d/override.conf

[Service]
ExecStart=
ExecStart=/usr/bin/docker daemon --storage-driver=overlay --graph=/dcos/docker -H fd:// $DOCKER_NETWORK_OPTIONS

 

重新启动docker

systemctl daemon-reload

systemctl restart docker 

 

测试

分别在两台节点上启动测试容器

docker run -d -it --name ip_test busybox

后网络互通,测试通过

references:
http://www.cnblogs.com/zhangeamon/p/6140074.html