Docker 三剑客之 Docker Swarm（基于 overlay 组网通信）

相关文章：Docker 三剑客之 Docker Swarm

这一篇主要是对 Docker Swarm 的完善，增加基于 overlay 组网通信，以便 Docker 容器可以跨主机访问。

不同主机间的容器之间通信方式，大概有三种：

• 使用端口映射：直接把容器的服务端口映射到主机上，主机直接通过映射出来的端口通信。
• 把容器放到主机所在的网段：修改 docker 的 ip 分配网段和主机一致，还要修改主机的网络结构。
• 第三方项目：flannel，weave 或者 pipework 等，这些方案一般都是通过 SDN 搭建 overlay 网络达到容器通信的。

在使用 overlay 组网通信之前，我们先安装 Docker，以及 Docker Machine（Linux 下）：

$ sudo curl -L https://github.com/docker/machine/releases/download/v0.13.0/docker-machine-`uname -s`-`uname -m` > /usr/local/bin/docker-machine
$ sudo chmod +x /usr/local/bin/docker-machine

使用脚本一键安装（Docker 镜像加速地址可以更换）：

#!/bin/bash

set -e

create_kv() {
    echo Creating kvstore machine.
    docker-machine create -d virtualbox \
        --engine-opt="registry-mirror=https://kvo9moak.mirror.aliyuncs.com" \
        kvstore
    docker $(docker-machine config kvstore) run -d \
        -p "8500:8500" \
        progrium/consul --server -bootstrap-expect 1
}

create_master() {
    echo Creating cluster master
    kvip=$(docker-machine ip kvstore)

    docker-machine create -d virtualbox \
        --swarm --swarm-master \
        --swarm-discovery="consul://${kvip}:8500" \
        --engine-opt="cluster-store=consul://${kvip}:8500" \
        --engine-opt="cluster-advertise=eth1:2376" \
        --engine-opt="registry-mirror=https://kvo9moak.mirror.aliyuncs.com" \
        swarm-manager
}

create_nodes(){
    kvip=$(docker-machine ip kvstore)
    echo Creating cluster nodes
    for i in 1 2; do
        docker-machine create -d virtualbox \
            --swarm \
            --swarm-discovery="consul://${kvip}:8500" \
            --engine-opt="cluster-store=consul://${kvip}:8500" \
            --engine-opt="cluster-advertise=eth1:2376" \
            --engine-opt="registry-mirror=https://kvo9moak.mirror.aliyuncs.com" \
            swarm-node${i}
    done
}

teardown(){
    docker-machine rm kvstore -y
    docker-machine rm -y swarm-manager
    for i in 1 2; do
        docker-machine rm -y swarm-node${i}
    done
}

case $1 in
    up)
        create_kv
        create_master
        create_nodes
        ;;
    down)
        teardown
        ;;
    *)
        echo "Unknow command..."
        exit 1
        ;;
esac

运行./cluster.sh up，就能自动生成四台主机：

• 一台 kvstore 运行 consul 服务。
• 一台 swarm master 机器，运行 swarm manager 服务。
• 两台 swarm node 机器，都是运行了 swarm node 服务和 docker daemon 服务。

查看四台主机的具体信息：

$ docker-machine ls
NAME            ACTIVE      DRIVER       STATE     URL                         SWARM                    DOCKER        ERRORS
kvstore         -           virtualbox   Running   tcp://192.168.99.100:2376                            v18.03.1-ce
swarm-manager   * (swarm)   virtualbox   Running   tcp://192.168.99.101:2376   swarm-manager (master)   v18.03.1-ce
swarm-node1     -           virtualbox   Running   tcp://192.168.99.102:2376   swarm-manager            v18.03.1-ce
swarm-node2     -           virtualbox   Running   tcp://192.168.99.103:2376   swarm-manager            v18.03.1-ce

接下来验证集群是否正确安装？在主机上运行下面命令（主机，不是 Docker 主机）：

$ eval $(docker-machine env --swarm swarm-manager)
$ docker info
Containers: 6
 Running: 6
 Paused: 0
 Stopped: 0
Images: 5
Server Version: swarm/1.2.8
Role: primary
Strategy: spread
Filters: health, port, containerslots, dependency, affinity, constraint, whitelist
Nodes: 3
 swarm-manager: 192.168.99.101:2376
  └ ID: K6WX:ZYFT:UEHA:KM66:BYHD:ROBF:Z5KG:UHNE:U37V:4KX2:S5SV:YSCA|192.168.99.101:2376
  └ Status: Healthy
  └ Containers: 2 (2 Running, 0 Paused, 0 Stopped)
  └ Reserved CPUs: 0 / 1
  └ Reserved Memory: 0 B / 1.021 GiB
  └ Labels: kernelversion=4.9.93-boot2docker, operatingsystem=Boot2Docker 18.03.1-ce (TCL 8.2.1); HEAD : cb77972 - Thu Apr 26 16:40:36 UTC 2018, ostype=linux, provider=virtualbox, storagedriver=aufs
  └ UpdatedAt: 2018-05-08T10:20:39Z
  └ ServerVersion: 18.03.1-ce
 swarm-node1: 192.168.99.102:2376
  └ ID: RPRC:AVBX:7CBJ:HUTI:HI3B:RI6B:QI6O:M2UQ:ZT2I:HZ6J:33BL:HY76|192.168.99.102:2376
  └ Status: Healthy
  └ Containers: 2 (2 Running, 0 Paused, 0 Stopped)
  └ Reserved CPUs: 0 / 1
  └ Reserved Memory: 0 B / 1.021 GiB
  └ Labels: kernelversion=4.9.93-boot2docker, operatingsystem=Boot2Docker 18.03.1-ce (TCL 8.2.1); HEAD : cb77972 - Thu Apr 26 16:40:36 UTC 2018, ostype=linux, provider=virtualbox, storagedriver=aufs
  └ UpdatedAt: 2018-05-08T10:21:09Z
  └ ServerVersion: 18.03.1-ce
 swarm-node2: 192.168.99.103:2376
  └ ID: MKQ2:Y7EO:CKOJ:MGFH:B77S:3EWX:7YJT:2MBQ:CJSN:XENJ:BSKO:RAZP|192.168.99.103:2376
  └ Status: Healthy
  └ Containers: 2 (2 Running, 0 Paused, 0 Stopped)
  └ Reserved CPUs: 0 / 1
  └ Reserved Memory: 0 B / 1.021 GiB
  └ Labels: kernelversion=4.9.93-boot2docker, operatingsystem=Boot2Docker 18.03.1-ce (TCL 8.2.1); HEAD : cb77972 - Thu Apr 26 16:40:36 UTC 2018, ostype=linux, provider=virtualbox, storagedriver=aufs
  └ UpdatedAt: 2018-05-08T10:21:06Z
  └ ServerVersion: 18.03.1-ce
Plugins:
 Volume:
 Network:
 Log:
Swarm:
 NodeID:
 Is Manager: false
 Node Address:
Kernel Version: 4.9.93-boot2docker
Operating System: linux
Architecture: amd64
CPUs: 3
Total Memory: 3.063GiB
Name: 85be09a37044
Docker Root Dir:
Debug Mode (client): false
Debug Mode (server): false
Experimental: false
Live Restore Enabled: false

WARNING: No kernel memory limit support

可以看到集群的具体信息。

然后，接下来在主机上创建 overlay 网络，创建命令：

$ docker network create -d overlay net1
d6a8a22298485a044b19fcbb62033ff1b4c3d4bd6a8a2229848

然后我们查看刚创建名称为net1的 overlay 网络，命令：

$ docker network ls
NETWORK ID          NAME                          DRIVER              SCOPE
d6a8a2229848        net1                          overlay             global
9c7f0e793838        swarm-manager/bridge          bridge              local
93787d9ba7ed        swarm-manager/host            host                local
72fd1e63889e        swarm-manager/none            null                local
c73e00c4c76c        swarm-node1/bridge            bridge              local
95983d8f1ef1        swarm-node1/docker_gwbridge   bridge              local
a8a569d55cc9        swarm-node1/host              host                local
e7fa8403b226        swarm-node1/none              null                local
7f1d219b5c08        swarm-node2/bridge            bridge              local
e7463ae8c579        swarm-node2/docker_gwbridge   bridge              local
9a1f0d2bbdf5        swarm-node2/host              host                local
bea626348d6d        swarm-node2/none              null                local

接下来，我们创建两个容器（主机上执行，使用 Docker Swarm 很方便），测试使用net1网络，是否可以相互访问，创建命令：

$ docker run -d --net=net1 --name=c1 -e constraint:node==swarm-node1 busybox top
dab080b33e76af0e4c71c9365a6e57b2191b7aacd4f715ca11481403eccce12a
$ docker run -d --net=net1 --name=c2 -e constraint:node==swarm-node2 busybox top
583fde42182a7e8f27527d5c55163a32102dba566ebe1f13d1951ac214849c8d

查看刚创建的容器运行情况：

$ docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
583fde42182a        busybox             "top"               3 seconds ago       Up 2 seconds                            swarm-node2/c2
dab080b33e76        busybox             "top"               18 seconds ago      Up 18 seconds                           swarm-node1/c1

接下来，我们查看net1网络的具体详情：

$ docker network inspect net1
[
    {
        "Name": "net1",
        "Id": "d6a8a2229848d40ce446f8f850a0e713a6c88a9b43583cc463f437f306724f28",
        "Created": "2018-05-08T09:21:42.408840755Z",
        "Scope": "global",
        "Driver": "overlay",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "Config": [
                {
                    "Subnet": "10.0.0.0/24",
                    "Gateway": "10.0.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "583fde42182a7e8f27527d5c55163a32102dba566ebe1f13d1951ac214849c8d": {
                "Name": "c2",
                "EndpointID": "b7fcb0039ab21ff06b36ef9ba008c324fabf24badfe45dfa6a30db6763716962",
                "MacAddress": "",
                "IPv4Address": "10.0.0.3/24",
                "IPv6Address": ""
            },
            "dab080b33e76af0e4c71c9365a6e57b2191b7aacd4f715ca11481403eccce12a": {
                "Name": "c1",
                "EndpointID": "8a80a83230edfdd9921357f08130fa19ef0b917bc4426aa49cb8083af9edb7f6",
                "MacAddress": "",
                "IPv4Address": "10.0.0.2/24",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {}
    }
]

可以看到，我们刚刚创建的两个容器信息（包含 IP 地址），也在里面。

然后我们测试下两个容器是否可以相互访问（直接 ping 容器名称，也可以访问）：

$ docker exec c1 ping -c 3 10.0.0.3
PING 10.0.0.3 (10.0.0.3): 56 data bytes
64 bytes from 10.0.0.3: seq=0 ttl=64 time=0.903 ms
64 bytes from 10.0.0.3: seq=1 ttl=64 time=0.668 ms
64 bytes from 10.0.0.3: seq=2 ttl=64 time=0.754 ms

--- 10.0.0.3 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.668/0.775/0.903 ms

$ docker exec c2 ping -c 3 10.0.0.2
PING 10.0.0.2 (10.0.0.2): 56 data bytes
64 bytes from 10.0.0.2: seq=0 ttl=64 time=0.827 ms
64 bytes from 10.0.0.2: seq=1 ttl=64 time=0.702 ms
64 bytes from 10.0.0.2: seq=2 ttl=64 time=0.676 ms

--- 10.0.0.2 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.676/0.735/0.827 ms

$ docker exec c2 ping -c 3 c1
PING c1 (10.0.0.2): 56 data bytes
64 bytes from 10.0.0.2: seq=0 ttl=64 time=1.358 ms
64 bytes from 10.0.0.2: seq=1 ttl=64 time=0.663 ms
64 bytes from 10.0.0.2: seq=2 ttl=64 time=0.761 ms

--- c1 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.663/0.927/1.358 ms

另附 Docker Swarm 架构图：

参考资料：

• Docker 1.9 的新网络特性，以及 Overlay 详解
• docker 跨主机网络：overlay 简介