docker内部ip与内网其它ip网段冲突导致无法访问的解决方法

现象：

宿主机和docker内部能互相访问非常正常，但docker内部访问外部网络内网其中一个网段172.18.0.x则无法访问。

排查

由于docker是精简过的系统，需另外安装网络相关命令
首先更新apt-get，否则在apt-get install 命令时会报E: Unable to locate package xx错误

apt-get update

安装网络工具

apt-get install -y net-tools

安装ping和telnet

apt-get install -y iputils-ping

apt-get install -y telnet

查看本机ip和网关，可用ifconfig和hostname -i命令

ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500inet 172.18.1.2  netmask 255.255.255.0  broadcast 172.18.1.255ether 02:42:ac:14:01:02  txqueuelen 0  (Ethernet)RX packets 224  bytes 20754 (20.2 KiB)RX errors 0  dropped 0  overruns 0  frame 0TX packets 226  bytes 1617336 (1.5 MiB)TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536inet 127.0.0.1  netmask 255.0.0.0loop  txqueuelen 1000  (Local Loopback)RX packets 0  bytes 0 (0.0 B)RX errors 0  dropped 0  overruns 0  frame 0TX packets 0  bytes 0 (0.0 B)TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

果然ip为172.18.0.x，与现在外部内网其中一段Ip重复了，但是并没有看到网关，再在cmd里通过docker network命令确认一下

docker network ls
NETWORK ID     NAME                   DRIVER    SCOPE
f2d743a9d1d7   bridge                 bridge    local
aa072983972b   host                   host      local
3689e62360ba   none                   null      local
0c92c70dfedd   webcloudapi_default    bridge    local

然后查询该网络详细

docker network inspect webcloudapi_default
[{"Name": "webcloudapi_default","Id": "0c92c70dfeddaca8722c5278831f07cb1555be23fdc74b8536ad2017eeb4ca3e","Created": "2023-08-31T01:23:30.156696Z","Scope": "local","Driver": "bridge","EnableIPv6": false,"IPAM": {"Driver": "default","Options": null,"Config": [{"Subnet": "172.18.0.0/16","Gateway": "172.18.0.1"}]},"Internal": false,"Attachable": false,"Ingress": false,"ConfigFrom": {"Network": ""},"ConfigOnly": false,"Containers": {},"Options": {},"Labels": {"com.docker.compose.network": "default","com.docker.compose.project": "webcloudapi","com.docker.compose.version": "2.20.2"}}
]

看到ip和网关都为172.18.0.x的，这时候确认问题，可以着手调整了。

解决方案

通过docker compose在部署的时候更改默认ip和网关即可。
webapi-compose.yml

version: '3'
networks:test-net:ipam:config:- subnet: 172.20.1.0/24gateway: 172.20.1.1
services:webcloudapi:image: webcloudapicontainer_name: webcloudapihostname: webcloudapiports:- 20020:80restart: alwaysnetworks:test-net:ipv4_address: 172.20.1.2

重新运行部署此yml文件（注意，这个操作会将原容器更改过的内容，包括新下载的命令软件全部重置）

docker compose -p webcloudapi -f webapi-compose.yml up -d

这时候再用api-get重新按上述步骤下载网络相关命令查看，ip和网关都变成172.20.1.x网段了，说明设置成功，但ping 172.18.0.x仍然无法连通，奇怪，后来终于发现问题所在，是之前部署的docker network配置还存在导致的问题

docker network ls
NETWORK ID     NAME                   DRIVER    SCOPE
f2d743a9d1d7   bridge                 bridge    local
aa072983972b   host                   host      local
3689e62360ba   none                   null      local
0c92c70dfedd   webcloudapi_default    bridge    local
d0916e722225   webcloudapi_test-net   bridge    local

上面的webcloudapi_default是原来的，webcloudapi_test-net是新建的，因此只要删除原来的即可。