Analysis of the implementation method of modifying the default network segment of Docker

background

All of the company's servers are purchased Alibaba Cloud ECS hosts. The default intranet segment is 172.16.0.0/12, and the services on the test server are basically deployed using Docker.
The Docker installed by my previous colleague on this machine is all default configuration, with the network segment of 172.17.0.0/24. In actual use, there will be a need to access the host machine through 172.17.0.1, which will conflict with other host machine IPs, so the default network segment of the container needs to be modified.

Workaround

1. Stop the Docker service on the host

sudo systemctl stop docker

2. Modify the container configuration file /etc/docker/daemon.json

sudo cat /etc/docker/daemon.json
{
  "registry-mirrors": ["https://gbs4gco0.mirror.aliyuncs.com"],
  "bip": "10.50.0.1/16",
}

As described in the above code, the bip field in the configuration file can set the docker network segment of the host machine and configure it to the private network address (192.168.0.0/10.0.0.0/172.0.0.0)

3. Start the Docker service

sudo systemctl daemon-reload
sudo systemctl start docker

4. Verify the docker-0 bridge address

sudo ifconfig
...
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
    inet 10.50.0.1 netmask 255.255.0.0 broadcast 10.50.255.255
    inet6 fe80::42:46ff:fe18:add5 prefixlen 64 scopeid 0x20<link>
    ether 02:42:46:18:ad:d5 txqueuelen 0 (Ethernet)
    RX packets 14697564 bytes 5943503139 (5.5 GiB)
    RX errors 0 dropped 0 overruns 0 frame 0
    TX packets 15379709 bytes 6846099156 (6.3 GiB)
    TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
...

At this point, the default network segment of Docker has been modified. You can check whether the IP of the previous container has been modified.

sudo docker container inspect alipne --format="{{.NetworkSettings.IPAdress}}"
10.50.0.2

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