二、--link与自定义网络

--link（不推荐使用）

思考一个场景，我们编写了一个微服务，项目不重启，数据库ip换掉了，我们希望可以处理这个问题，可以用名字来访问？

1.启动两个容器如下

[root@docker ~]# docker ps

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

79bec4d5841a centos "/bin/bash" 28 minutes ago Up 28 minutes centos02

95937ebb5ce8 centos "/bin/bash" 29 minutes ago Up 29 minutes centos01

[root@docker ~]# docker exec -it centos01 ping centos02

ping: centos02: Name or service not known

我们发现不能ping通：

解决办法--link即可解决连接问题，但是反向连接不能ping通

[root@docker ~]# docker run -d -it --name centos03 --link centos01 --link centos02 centos

ed7e71239e34507cd1aa32590df51f0a0fdc335d7d9ef6503c170197fb1ab92e

[root@docker ~]# docker exec -it centos03 ping centos01

PING centos01 (172.17.0.2) 56(84) bytes of data.

64 bytes from centos01 (172.17.0.2): icmp_seq=1 ttl=64 time=0.055 ms

64 bytes from centos01 (172.17.0.2): icmp_seq=2 ttl=64 time=0.043 ms

可以查看网卡信息

[root@docker ~]# docker network inspect bridge

[

{

"Name": "bridge",

"Id": "219769a742011931a0b08b03fc00f6135ad1bcabce1cfa93bc68902b532a2a3b",

"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,

"Containers": {

"79bec4d5841a7f4bba483e0a0107383eea759d863ade5c6bf0d2c7cdf5693950": {

"Name": "centos02",

"EndpointID": "0e862a4d7bd09adaed475d9844af2d72a07a412b72534bfdac107af42b9991ef",

"MacAddress": "02:42:ac:11:00:03",

"IPv4Address": "172.17.0.3/16",

"IPv6Address": ""

"95937ebb5ce8d7571232306218f44d7da65dc6e9aa8b901e8c156315199ec759": {

"Name": "centos01",

"EndpointID": "4ed26158cd299b9d834e9b90142e1131e62f0c107124f7c4babd54fa3fa58962",

"MacAddress": "02:42:ac:11:00:02",

"IPv4Address": "172.17.0.2/16",

"IPv6Address": ""

"ed7e71239e34507cd1aa32590df51f0a0fdc335d7d9ef6503c170197fb1ab92e": {

"Name": "centos03",

"EndpointID": "a2eacc59f98083eccfa2ce4f8b00f7d311ab056cd0118b0bdbaad0c88cbbbcf5",

"MacAddress": "02:42:ac:11:00:04",

"IPv4Address": "172.17.0.4/16",

"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": {}

}

]

探索 inspect

其实这个centos03就是配置了centos01-02的配置

#查看hosts配置，在这里原理发现

[root@docker ~]# docker exec -it centos03 cat /etc/hosts

127.0.0.1 localhost

::1 localhost ip6-localhost ip6-loopback

fe00::0 ip6-localnet

ff00::0 ip6-mcastprefix

ff02::1 ip6-allnodes

ff02::2 ip6-allrouters

172.17.0.2 centos01 95937ebb5ce8

172.17.0.3 centos02 79bec4d5841a

172.17.0.4 ed7e71239e34

本质探究：--link操作就是在hosts配置中增加了一个centos01-2的映射

在真实项目中已经不建议使用--link了

在实际中我们采用自定义网络，不使用docker0

docker的问题：它不支持容器名连接访问

自定义网络

[root@docker ~]# docker network ls #查看所有网卡

docker network rm 删除网卡

[root@docker ~]# docker network ls

NETWORK ID NAME DRIVER SCOPE

219769a74201 bridge bridge local

f6b9d84b1f81 host host local

47132fb890ac none null local

网络模式

bridge ：桥接(默认，自己创建网络也推荐使用bridge模式)

none: 不配置网络

host: 和宿主机共享网络

container: 容器网络连通！（使用较少！局限性很大）

测试：

#我们直接启动的命令 --network bridge ，而这个就是我们的docker0

[root@docker ~]# docker run -d -P --name centos1 --network bridge centos

#docker0 ：默认，域名不能访问，使用--link可以打通连接

#我们可以自定义一个网络

[root@docker ~]# docker network create --help #帮助命令查看

[root@docker ~]# docker network create --driver bridge --subnet 192.168.1.0/24 --gateway 192.168.1.1 mynet

2bb4bf4c05391ed5349957522374d4e0a1043b3767f3fa7fe15a6f8754437e0b

[root@docker ~]# docker network ls

NETWORK ID NAME DRIVER SCOPE

219769a74201 bridge bridge local

f6b9d84b1f81 host host local

2bb4bf4c0539 mynet bridge local

47132fb890ac none null local

参数讲解：

--driver bridge ：指定模式为桥接

--subnet：子网地址

--gateway：网关

[root@docker ~]# docker network inspect mynet

[

{

"Name": "mynet",

"Id": "2bb4bf4c05391ed5349957522374d4e0a1043b3767f3fa7fe15a6f8754437e0b",

"Scope": "local",

"Driver": "bridge",

"EnableIPv6": false,

"IPAM": {

"Driver": "default",

"Options": {},

"Config": [

{

"Subnet": "192.168.1.0/24",

"Gateway": "192.168.1.1"

}

]

"Internal": false,

"Containers": {},

"Options": {},

"Labels": {}

}

]

至此我们自己的网络就创建好了

接下来启动两个容器测试：

[root@docker ~]# docker run -d -it -P --name cenos01 --network mynet centos

0f928c84f9f4615e432198d78a5e72062334041117b5b74ce66e327422dc6f78

[root@docker ~]# docker run -d -it -P --name cenos02 --network mynet centos

6dcaf8d1698263309bb87d5f535981679e73958f7cb63d2fe69a9a3fa74d6808

[root@docker ~]# docker network inspect mynet

[

{

"Name": "mynet",

"Id": "2bb4bf4c05391ed5349957522374d4e0a1043b3767f3fa7fe15a6f8754437e0b",

"Scope": "local",

"Driver": "bridge",

"EnableIPv6": false,

"IPAM": {

"Driver": "default",

"Options": {},

"Config": [

{

"Subnet": "192.168.1.0/24",

"Gateway": "192.168.1.1"

}

]

"Internal": false,

"Containers": {

"0f928c84f9f4615e432198d78a5e72062334041117b5b74ce66e327422dc6f78": {

"Name": "cenos01",

"EndpointID": "c6a6451c319156074642e6c26d7305977c7619bd5fe3faeac1bab656dc7c81e5",

"MacAddress": "02:42:c0:a8:01:02",

"IPv4Address": "192.168.1.2/24",

"IPv6Address": ""

"6dcaf8d1698263309bb87d5f535981679e73958f7cb63d2fe69a9a3fa74d6808": {

"Name": "cenos02",

"EndpointID": "9346da6d8559ae555dd47a40e4f2c56e8d59f7b7d2fba674ec95f1eaac26d9ba",

"MacAddress": "02:42:c0:a8:01:03",

"IPv4Address": "192.168.1.3/24",

"IPv6Address": ""

}

"Options": {},

"Labels": {}

}

]

#再次测试ping连接不使用--link也可以ping名字ping通

[root@docker ~]# docker exec -it cenos01 ping cenos02

PING cenos02 (192.168.1.3) 56(84) bytes of data.

64 bytes from cenos02.mynet (192.168.1.3): icmp_seq=1 ttl=64 time=0.045 ms

64 bytes from cenos02.mynet (192.168.1.3): icmp_seq=2 ttl=64 time=0.047 ms

64 bytes from cenos02.mynet (192.168.1.3): icmp_seq=3 ttl=64 time=0.070 ms

我们自定义的网络docker都已经帮我们维护好了对应的关系推荐使用自定义网络

好处：保证不同的集群使用不同的网络，保证集群是安全和健康的

原文地址：https://www.cnblogs.com/momo6656/p/15342975.html