Docker 网络 Flannel

flannel 安装

sudo yum install kernel-headers golang gcc
yum install flannel

flannel 配置

在etcd中设置变量

etcdctl set /coreos.com/network/config '{ "Network": "172.17.0.0/16" }'

配置flannel

vi /etc/sysconfig/flanneld

# Flanneld configuration options

# etcd url location.  Point this to the server where etcd runs
FLANNEL_ETCD="http://10.1.99.13:2379,10.1.99.14:2379,10.1.99.15:2379"

# etcd config key.  This is the configuration key that flannel queries
# For address range assignment
FLANNEL_ETCD_KEY="/coreos.com/network"

# Any additional options that you want to pass
#FLANNEL_OPTIONS=""

重新启动flannel

systemctl daemon-reload flanneld

systemctl restart flanneld

flannel服务启动

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

cat /run/flannel/subnet.env
FLANNEL_NETWORK=172.17.0.0/
FLANNEL_SUBNET=172.17.50.1/
FLANNEL_MTU=
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

FLANNEL_NETWORK=172.17.0.0/
FLANNEL_SUBNET=172.17.50.1/
FLANNEL_MTU=
FLANNEL_IPMASQ=false
[root@v4 ~]# cat /run/flannel/docker
DOCKER_OPT_BIP="--bip=172.17.50.1/24"
DOCKER_OPT_IPMASQ="--ip-masq=true"
DOCKER_OPT_MTU="--mtu=1472"
DOCKER_NETWORK_OPTIONS=" --bip=172.17.50.1/24 --ip-masq=true --mtu=1472 "

配置docker

systemctl 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 /usr/lib/systemd/system/docker.service

ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock $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