Of Stack

Docker specifies the method of container ip for network bridge mode

  • 2020-05-24 06:34:01
  • OfStack

preface

It is well known that bridge mode is the default network setting of Docker. This mode allocates Network Namespace for each container, sets IP, etc., and connects Docker containers on one host to a virtual bridge. Let's take a look at how Docker specifies container ip for network bridge mode.

Implementation method

You cannot specify ip to the container by simply creating an bridge mode network 


[root@vultrvpn conf.d]# docker network create --driver bridge wordpress_net
ad1ff3d972e8bfe6d992a8403a98f46784aa75d5514adbf35ee6ae4528513be7
[root@vultrvpn conf.d]# docker network ls
NETWORK ID   NAME    DRIVER    SCOPE
38fab5c74b87  bridge    bridge    local    
f0cf94dd0c5e  host    host    local    
465a31c55aa1  none    null    local    
ad1ff3d972e8  wordpress_net  bridge    local

A network of wordpress_net has been created. Create a container on this network module and specify ip 


[root@vultrvpn conf.d]# docker run -d --name db_mysql -m 220m --memory-swap 220m -v /data/docker_project/db_mysql/data:/var/lib/mysql -v /data/docker_project/db_mysql/conf:/etc/mysql/conf.d -e MYSQL_ROOT_PASSWORD=qwe123 --network=wordpress_net --ip=172.18.0.2 mysql:5.7
da497e56bd4b0f3434dd4f81534096574d167354dc508b657ceb390ba8e63771
docker: Error response from daemon: User specified IP address is supported only when connecting to networks with user configured subnets.

An error was prompted. To configure ip, you need to specify an subnet for this network. So let's redo a network. 


docker network create --driver bridge --subnet 172.25.0.0/16 wordpress_net


[root@vultrvpn conf.d]# docker network inspect wordpress_net 
[
 {
  "Name": "wordpress_net",
  "Id": "925e64493df9b674ef9bdadaae380c8a335aa6353e48b447cb5d910df19c3a3e",
  "Scope": "local",
  "Driver": "bridge",
  "EnableIPv6": false,
  "IPAM": {
   "Driver": "default",
   "Options": {},
   "Config": [
    {
     "Subnet": "172.25.0.0/16"
    }
   ]
  },
  "Internal": false,
  "Containers": {},
  "Options": {},
  "Labels": {}
 }
]

Specify 1 ip for the container 


[root@vultrvpn conf.d]# docker run -d --name my_vpn -m 100m --memory-swap 100m -e WORDPRESS_DB_HOST=172.25.0.2 -e WORDPRESS_DB_USER=root -e WORDPRESS_DB_PASSWORD=qwe123 -e WORDPRESS_DB_NAME=myvpn -p 8001:80 --network=wordpress_net wordpress:4.6
096518d84419476f71647a8c70c91c3f336ef8772af50672b88a9c1fd7b3a719
[root@vultrvpn conf.d]# docker ps -a
CONTAINER ID  IMAGE     COMMAND     CREATED    STATUS      PORTS     NAMES
096518d84419  wordpress:4.6   "/entrypoint.sh apach" 47 seconds ago  Up 47 seconds    0.0.0.0:8001->80/tcp my_vpn
6d23ed99db20  wordpress:4.6   "/entrypoint.sh apach" About a minute ago Up About a minute   0.0.0.0:8000->80/tcp my_wordpress
ade42edf5a93  mysql:5.7    "docker-entrypoint.sh" 3 minutes ago  Up 3 minutes    3306/tcp    db_mysql

The normal to create

View network card information 


[root@vultrvpn conf.d]# docker network inspect wordpress_net 
[
 {
  "Name": "wordpress_net",
  "Id": "925e64493df9b674ef9bdadaae380c8a335aa6353e48b447cb5d910df19c3a3e",
  "Scope": "local",
  "Driver": "bridge",
  "EnableIPv6": false,
  "IPAM": {
   "Driver": "default",
   "Options": {},
   "Config": [
    {
     "Subnet": "172.25.0.0/16"
    }
   ]
  },
  "Internal": false,
  "Containers": {
   "096518d84419476f71647a8c70c91c3f336ef8772af50672b88a9c1fd7b3a719": {
    "Name": "my_vpn",
    "EndpointID": "e44636c2b3a49d4aedaad68cd6ca17aea3a9fe4f71afecb27219a6412701536a",
    "MacAddress": "02:42:ac:19:00:04",
    "IPv4Address": "172.25.0.4/16",
    "IPv6Address": ""
   },
   "6d23ed99db20f17d99dd5dcf6cc65f5ced8cb936917dee044914cf278179150c": {
    "Name": "my_wordpress",
    "EndpointID": "3c765d5953428c1d66be584eb0d34b58f6eee3f598e3a37263d54d77e2b87263",
    "MacAddress": "02:42:ac:19:00:03",
    "IPv4Address": "172.25.0.3/16",
    "IPv6Address": ""
   },
   "ade42edf5a934b02f7bb741bd5a45a282a50d3a49e9f1866579e8f93fef22a0e": {
    "Name": "db_mysql",
    "EndpointID": "2322bfb9da72b3b6db68d59cea97172e66b960ca5b782bd2fa7d09f9c93f0288",
    "MacAddress": "02:42:ac:19:00:02",
    "IPv4Address": "172.25.0.2/16",
    "IPv6Address": ""
   }
  },
  "Options": {},
  "Labels": {}
 }
]

conclusion

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