【Docker那些事】系列文章

Dockerfile 文件结构、docker镜像构建过程详细介绍
Dockerfile文件中CMD指令与ENTRYPOINT指令的区别
构建Docker镜像指南，含实战案例
Docker 制作自定义化的Tomcat镜像
docker 安装 mysql 并映射数据库存放路径及配置文件
docker安装tomcat 映射配置文件、日志文件
docker安装nginx，配置nginx，并成功访问
docker安装redis并将配置文件和数据文件映射到外部
Docker 容器互联 --link 和 自定义网络

–link

docker run -d -P --name mytomcat01 tomcat
# mytomcat02容器通过 --link 连接mytomcat01
docker run -d -P --name mytomcat02 --link mytomcat01 tomcat

测试

docker exec -it mytomcat02 ping mytomcat01
docker exec -it mytomcat01 ping mytomcat02

在使用mytomcat02 连通 mytomcat01测试是没有问题的，而mytomcat01 连通 mytomcat02是不行的。

自定义网络

查看所有的docker网络

网络模式
bridge：桥接，docker默认的模式
none：不配置网络
host：和宿主机共享网络
container：容器内网络连通（用得少， 局限性很大）

# docker默认启动容器网络 --net bridge
docker run -d -P --name mytomcat tomcat
docker run -d -P --name mytomcat --net bridge tomcat

创建自定义网络

1. 使用bridge桥接模式
2. 子网掩码192.168.0.0/16
3. 网关192.1678.0.1
4. 设置自定义网络名称为mynet

docker network create --driver bridge --subnet 192.168.0.0/16 --gateway 192.168.0.1 mynet

查看所有的docker网络，可以看到新定义的mynet网络规则

docker network ls

查看自定义网络mynet的详细配置

docker network inspect mynet

使用自定义网络进行测试

启动两个tomcat容器进行网络测试

docker run -d -P --name mytomcat01 --net mynet tomcat
docker run -d -P --name mytomcat02 --net mynet tomcat

再次查看自定义网络，会发现启动的两个tomcat容器分别占用了192.168.0.2和192.168.0.3。

[root@berbai01 ~]# docker network inspect mynet
[{"Name": "mynet","Id": "d20f927dca673bfed0171621dbaa7a188e1ace53527254fafd563b84a9b4b126","Created": "2021-08-28T16:10:48.145033744+08:00","Scope": "local","Driver": "bridge","EnableIPv6": false,"IPAM": {"Driver": "default","Options": {},"Config": [{"Subnet": "192.168.0.0/16","Gateway": "192.168.0.1"}]},"Internal": false,"Attachable": false,"Ingress": false,"ConfigFrom": {"Network": ""},"ConfigOnly": false,"Containers": {"47cc0d4b74a1102fde953848139f6861e35d4d82ac54a676631c4b15bd8edfae": {"Name": "mytomcat01","EndpointID": "023dff7f5fd886722583cae01182d0d864e3af645cfbdbccbd7d74b74edd0cf6","MacAddress": "02:42:c0:a8:00:02","IPv4Address": "192.168.0.2/16","IPv6Address": ""},"a1c5e80a0a09acb38eb07e6abdca6e4d85c0c5da9ee773e69201ff14d43e337b": {"Name": "mytomcat02","EndpointID": "e2a8ada261cccbed8f84ade28c4f390f73643a7236e958be560eaf0c1bf947c8","MacAddress": "02:42:c0:a8:00:03","IPv4Address": "192.168.0.3/16","IPv6Address": ""}},"Options": {},"Labels": {}}
]

测试两个容器的网络连通情况

# 通过容器的ip访问
docker exec -it mytomcat01 ping 192.168.0.3
# 通过容器名访问
docker exec -it mytomcat01 ping mytomcat02
docker exec -it mytomcat02 ping mytomcat01

两者都会可以连通的

小结

docker使用自定义网络，可以自动实现容器的互联。
使用自定义网络的优势：在搭建集群时，可以根据不同的集群使用不同的网络，保证集群是安全和健康的

不同网络的连通

连通所使用的指令

docker network connect [OPTIONS] NETWORK CONTAINER

用默认bridge模式和自定义mynet模式进行测试

# 默认bridge模式运行
docker run -d -P --name tomcat01 tomcat
docker run -d -P --name tomcat02 tomcat
# 自定义mynet模式运行
docker run -d -P --name tomcatmynet01 --net mynet tomcat

先测试tomcat01和tomcat02能不能连通tomcatmynet01

docker exec -it tomcat01 ping tomcatmynet01
docker exec -it tomcat02 ping tomcatmynet01

显然是不能连通的。

查看bridge模式和mynet模式的配置

docker network inspect bridge
docker network inspect mynet

bridge模式网段是171.17.0.0/16
mynet模式网段是192.168.0.0/16
学过网络原理的同学都知道不同网段是不能进行连通的。

[root@berbai01 ~]# docker network inspect bridge
[{"Name": "bridge","Id": "1f223afddbadd639a936453c1eb184edf9f6ae9219e31babd69e240a39f5c195","Created": "2021-08-28T16:28:14.602655353+08:00","Scope": "local","Driver": "bridge","EnableIPv6": false,"IPAM": {"Driver": "default","Options": null,"Config": [{"Subnet": "172.17.0.0/16","Gateway": "172.17.0.1"}]},"Internal": false,"Attachable": false,"Ingress": false,"ConfigFrom": {"Network": ""},"ConfigOnly": false,"Containers": {"76c15c6238d6485d5379624300d4ea7f3796ead8f7df5ac38e29029ab7892d3a": {"Name": "tomcat01","EndpointID": "63cb04611404ba6668319d76af24f12830b7db09a597a625ad88f60b576af1ff","MacAddress": "02:42:ac:11:00:02","IPv4Address": "172.17.0.2/16","IPv6Address": ""},"b7cd5d28c3a6388cae45da8d1399ddf22a303a1f5899efaa673290c3a411cc32": {"Name": "tomcat02","EndpointID": "57dc989fb590b9431ae9aed7b291362c224e11ad1f861e7e84bd859f1b5589e9","MacAddress": "02:42:ac:11:00:03","IPv4Address": "172.17.0.3/16","IPv6Address": ""}},"Options": {"com.docker.network.bridge.default_bridge": "true","com.docker.network.bridge.enable_icc": "true","com.docker.network.bridge.enable_ip_masquerade": "true","com.docker.network.bridge.host_binding_ipv4": "0.0.0.0","com.docker.network.bridge.name": "docker0","com.docker.network.driver.mtu": "1500"},"Labels": {}}
]
[root@berbai01 ~]#
[root@berbai01 ~]# docker network inspect mynet
[{"Name": "mynet","Id": "d20f927dca673bfed0171621dbaa7a188e1ace53527254fafd563b84a9b4b126","Created": "2021-08-28T16:10:48.145033744+08:00","Scope": "local","Driver": "bridge","EnableIPv6": false,"IPAM": {"Driver": "default","Options": {},"Config": [{"Subnet": "192.168.0.0/16","Gateway": "192.168.0.1"}]},"Internal": false,"Attachable": false,"Ingress": false,"ConfigFrom": {"Network": ""},"ConfigOnly": false,"Containers": {"f554e062918dc35ac7e1ce858b7cb9fc9e5f0a7eaadc90bdce8fdaad00b9b1ae": {"Name": "tomcatmynet01","EndpointID": "3e4b65c4826425e1d11397544055e0aa33cf113ccf7045f9c20b866ba6a5cdb3","MacAddress": "02:42:c0:a8:00:02","IPv4Address": "192.168.0.2/16","IPv6Address": ""}},"Options": {},"Labels": {}}
]
[root@berbai01 ~]#

建立bride模式容器与mynet模式容器的连接

docker network connect mynet tomcat01
# 再次查看mynet配置
docker network inspect mynet

这里发现tomcat01也加入了mynet网络中，说明tomcat01容器已经可以与mynet网络中容器连通。下面通过测试也可以得知。

[root@berbai01 ~]# docker network inspect mynet
[{"Name": "mynet","Id": "d20f927dca673bfed0171621dbaa7a188e1ace53527254fafd563b84a9b4b126","Created": "2021-08-28T16:10:48.145033744+08:00","Scope": "local","Driver": "bridge","EnableIPv6": false,"IPAM": {"Driver": "default","Options": {},"Config": [{"Subnet": "192.168.0.0/16","Gateway": "192.168.0.1"}]},"Internal": false,"Attachable": false,"Ingress": false,"ConfigFrom": {"Network": ""},"ConfigOnly": false,"Containers": {"76c15c6238d6485d5379624300d4ea7f3796ead8f7df5ac38e29029ab7892d3a": {"Name": "tomcat01","EndpointID": "0852fbe26a3d37668c2deff948671bc6a52749068f518104f99e8ad5ad3d7057","MacAddress": "02:42:c0:a8:00:03","IPv4Address": "192.168.0.3/16","IPv6Address": ""},"f554e062918dc35ac7e1ce858b7cb9fc9e5f0a7eaadc90bdce8fdaad00b9b1ae": {"Name": "tomcatmynet01","EndpointID": "3e4b65c4826425e1d11397544055e0aa33cf113ccf7045f9c20b866ba6a5cdb3","MacAddress": "02:42:c0:a8:00:02","IPv4Address": "192.168.0.2/16","IPv6Address": ""}},"Options": {},"Labels": {}}
]
[root@berbai01 ~]#

再次测试tomcat01与tomcatmynet01的连通

docker exec -it tomcat01 ping tomcatmynet01

经测试tomcat01已经可以与tomcatmynet01进行连通

tomcat02与tomcatmynet01的连通情况呢？

docker exec -it tomcat02 ping tomcatmynet01

可以看到如果没有与mynet进行connect，是不能进行连通的

小结

docker容器的网络互通其实就是赋予了一个容器多个ip，如上述试验中tomcat01被新赋予了ip192.168.0.3，于是tomcat01可以完成与mynet网络中容器进行连通。
而tomcat02并没有与mynet进行connect连接，没有与mynet相同的网段地址，依然不能与mynet中容器进行连通。

以上如有错误，麻烦大家评论指正。