Explain in detail the method of Docker container communication across hosts

By default, the Docker container needs to communicate across hosts. Both host nodes need to be in the same network segment. As long as the hosts of the two Docker containers can communicate with each other and the container uses net network mode, the implementation mode is changed to bridge mode communication.

In addition, we can also create an overlay network for different hosts to communicate across nodes by using third-party tools, which will be implemented using Flanneld

Install etcd

Create a cat / etc/etcd/etcd.conf file

# [member] ETCD_NAME=infra1 ETCD_DATA_DIR= "/ var/lib/etcd" ETCD_LISTEN_PEER_URLS= "http://192.168.2.150:2380" ETCD_LISTEN_CLIENT_URLS=" http://192.168.2.150:2379" # [cluster] ETCD_INITIAL_ADVERTISE_PEER_URLS= "http://192.168.2.150:2380" ETCD_INITIAL_CLUSTER_TOKEN=" etcd-cluster "ETCD_ADVERTISE_CLIENT_URLS=" http://192.168.2.150:2379"

Create / etc/systemd/system/etcd.service file

[Unit] Description=Etcd ServerAfter=network.targetAfter=network-online.targetWants=network-online.targetDocumentation= https://github.com/coreos[Service]Type=notifyWorkingDirectory=/var/lib/etcd/EnvironmentFile=-/etc/etcd/etcd.confExecStart=/usr/local/bin/etcd\-- name ${ETCD_NAME}\-- initial-advertise-peer-urls ${ETCD_INITIAL_ADVERTISE_PEER_URLS}\-- listen-peer-urls ${ETCD_LISTEN_PEER_URLS}\-listen-client-urls ${ETCD_LISTEN_CLIENT_URLS} Http://127.0.0.1:2379\-- advertise-client-urls ${ETCD_ADVERTISE_CLIENT_URLS}\-- initial-cluster-token ${ETCD_INITIAL_CLUSTER_TOKEN}\-- initial-cluster infra1= http://192.168.2.150:2380,infra2=http://192.168.2.151:2380\-- initial-cluster-state new\-data-dir=$ {ETCD_DATA_DIR} Restart=on-failureRestartSec=5LimitNOFILE=65536 [Install] WantedBy=multi-user.target

Start systemctl start etcd

Create a directory in etcd: etcdctl-- endpoints= http://192.168.2.150:2379,http://192.168.5.151:2379

Mkdir / kube-centos/network

Create a config node and write network configuration information:

Etcdctl-- endpoints= http://172.20.0.113:2379,http://172.20.0.114:2379 mk / kube-centos/network/config'{"Network": "192.167.0.0 vxlan 16", "SubnetLen": 24, "Backend": {"Type": "vxlan"}'

Flanneld

Create / etc/sysconfig/flanneld file

# Flanneld configuration options # etcd url location. Point this to the server where etcd runsFLANNEL_ETCD_ENDPOINTS= "http://127.0.0.1:2379"# etcd config key. This is the configuration key that flannel queries# For address range assignment# FLANNEL_ETCD_PREFIX= "/ kube-centos/network" FLANNEL_ETCD_PREFIX= "/ coreos.com/network" # Any additional options that you want to passFLANNEL_OPTIONS= "- iface=eth0"

Create / usr/lib/systemd/system/flanneld.service file

[Unit] Description=Flanneld overlay address etcd agentAfter=network.targetAfter=network-online.targetWants=network-online.targetAfter=etcd.serviceBefore= docker.service [service] Type=notifyEnvironmentFile=/etc/sysconfig/flanneldEnvironmentFile=-/etc/sysconfig/docker-network#ExecStart=/usr/bin/flanneld-start $FLANNEL_OPTIONSExecStart=/usr/bin/flanneld-start-etcd-endpoints= http://192.168.2.150:2379,http://192.168.2.151:2379-iface=ens33#ExecStart=/usr/bin/flanneld-start-etcd-endpoints= http://192.168.2.150:2379, Http://192.168.2.151:2379-etcd- prefix=/kube-centos/networkExecStartPost=/usr/libexec/flannel/mk-docker-opts.sh-k DOCKER_NETWORK_OPTIONS-d / run/flannel/dockerRestart=on-failure [Install] WantedBy=multi-user.targetRequiredBy=docker.service

Start systemctl start flanneld

The / run/flannel/subnet.env file is produced after flannled starts.

Modify the configuration of docker startup parameters and add:

EnvironmentFile=/run/flannel/subnet.env--bip=$ {FLANNEL_SUBNET}-- ip-masq=$ {FLANNEL_IPMASQ}-- mtu=$ {FLANNEL_MTU}

Restart docker, and docker will assign ip to container using the IP address range configured by flanneld

Launch the container on two nodes: docker run-it-rm busybox sh

View the container IP,ping of one host node and the other host node IP

View the container IP,ping of one host node and the other host node IP

It can be connected at this time.

Note whether the iptables configuration is correct

The above is the whole content of this article, I hope it will be helpful to your study, and I also hope that you will support it.