Criando a sua rede bridge

Criação de uma rede bridge personalizada ao invés de utilizar a rede bridge padrão disponibilizada no momento da instalação do Docker

Documentação do Docker Network:

Bridge network driverDocker Documentation

Nenhum container existente:

$ docker container ls -a
CONTAINER ID   IMAGE     COMMAND   CREATED   STATUS    PORTS     NAMES

Criação de rede bridge chamada custom:

$ docker network create custom
02c206fcb9c9ad9f850c5de72758d80649ee27e9780e72235238f38be126f953
$ docker network ls
NETWORK ID     NAME      DRIVER    SCOPE
29f83204d89d   bridge    bridge    local
02c206fcb9c9   custom    bridge    local
73f2d51a39de   host      host      local
9198ba9fc6fd   none      null      local

$docker network inspect custom
[
    {
        "Name": "custom",
        "Id": "02c206fcb9c9ad9f850c5de72758d80649ee27e9780e72235238f38be126f953",
        "Created": "2024-08-28T07:51:54.43905252-03:00",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "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": {}
    }
]

Foi criada uma sub rede 172.18.0.0/16.

Diferente da sub rede padrão disponibilizada na instalação:

$ docker network inspect bridge | grep -i subnet
                    "Subnet": "172.17.0.0/16",

Criação de container nginx com a definição do nome do container:

$ docker container run --name nginx -d nginx
dadeac1f82444eaa6d0aba061022b0fccc9c115182a21d6d64bb0dcd7ee833fd

Criação de container ubuntu em modo interativo com a instalação do curl e a tentativa de acessar o container nginx:

$ docker container run -it ubuntu /bin/bash
root@70b6fbcf8952:/# apt update && apt install curl --yes
root@70b6fbcf8952:/# curl
curl: try 'curl --help' or 'curl --manual' for more information
root@70b6fbcf8952:/# curl http://nginx
curl: (6) Could not resolve host: nginx

Não foi possível resolver o nome do host. Pois a rede não foi definida no momento da criação do container

Lista dos containers em execução e a inspeção do container nginx sendo executado na rede padrão da instalação Docker:

$ docker container ls
CONTAINER ID   IMAGE     COMMAND                  CREATED              STATUS              PORTS     NAMES
70b6fbcf8952   ubuntu    "/bin/bash"              42 seconds ago       Up 41 seconds                 infallible_clarke
dadeac1f8244   nginx     "/docker-entrypoint.…"   About a minute ago   Up About a minute   80/tcp    nginx

$ docker container inspect dadeac1f8244 | grep -Ei "network|ipaddress|gateway"
            "NetworkMode": "bridge",
        "NetworkSettings": {
            "SecondaryIPAddresses": null,
            "Gateway": "172.17.0.1",
            "IPAddress": "172.17.0.2",
            "IPv6Gateway": "",
            "Networks": {
                    "NetworkID": "29f83204d89d7bc84b1038a44e0c67b88fccd06e9e5971ae0f1d574a29dbe147",
                    "Gateway": "172.17.0.1",
                    "IPAddress": "172.17.0.2",
                    "IPv6Gateway": "",

Conectar o container nginx na rede custom:

$ docker network connect custom nginx
$ docker container inspect dadeac1f8244
...
            "NetworkMode": "bridge",
...
        "NetworkSettings": {
...
            "Gateway": "172.17.0.1",
            "GlobalIPv6Address": "",
            "GlobalIPv6PrefixLen": 0,
            "IPAddress": "172.17.0.2",
...
            "Networks": {
                "bridge": {
                    "IPAMConfig": null,
                    "Links": null,
                    "Aliases": null,
                    "MacAddress": "02:42:ac:11:00:02",
                    "DriverOpts": null,
                    "NetworkID": "29f83204d89d7bc84b1038a44e0c67b88fccd06e9e5971ae0f1d574a29dbe147",
                    "EndpointID": "c76d9dc76852d5ba750d9c05991d2ffb76ecab02ed7e0a8d5b58487ba744c9b4",
                    "Gateway": "172.17.0.1",
                    "IPAddress": "172.17.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "DNSNames": null
                },
                "custom": {
                    "IPAMConfig": {},
                    "Links": null,
                    "Aliases": [],
                    "MacAddress": "02:42:ac:12:00:02",
                    "DriverOpts": {},
                    "NetworkID": "02c206fcb9c9ad9f850c5de72758d80649ee27e9780e72235238f38be126f953",
                    "EndpointID": "460803913e762d2214dfd278a81f00d31f41606fbb17fd39f0f3b26d00b80da1",
                    "Gateway": "172.18.0.1",
                    "IPAddress": "172.18.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "DNSNames": [
                        "nginx",
                        "dadeac1f8244"
                    ]
                }
            }
        }
    }
]

Desconectar a rede bridge:

$ docker network disconnect bridge nginx
$ docker container inspect dadeac1f8244
...
            "Networks": {
                "custom": {
                    "IPAMConfig": {},
                    "Links": null,
                    "Aliases": [],
                    "MacAddress": "02:42:ac:12:00:02",
                    "DriverOpts": {},
                    "NetworkID": "02c206fcb9c9ad9f850c5de72758d80649ee27e9780e72235238f38be126f953",
                    "EndpointID": "460803913e762d2214dfd278a81f00d31f41606fbb17fd39f0f3b26d00b80da1",
                    "Gateway": "172.18.0.1",
                    "IPAddress": "172.18.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "DNSNames": [
                        "nginx",
                        "dadeac1f8244"
                      ]
                }
            }
        }
    }
]

Para que o container do ubuntu consiga acessar o container do nginx ele precisa estar na mesma sub rede:

$ docker container ls
CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS          PORTS     NAMES
70b6fbcf8952   ubuntu    "/bin/bash"              21 minutes ago   Up 21 minutes             infallible_clarke
dadeac1f8244   nginx     "/docker-entrypoint.…"   22 minutes ago   Up 22 minutes   80/tcp    nginx
$ docker network connect custom infallible_clarke
$ docker network disconnect bridge infallible_clarke
$ docker container inspect infallible_clarke
...
            "Networks": {
                "custom": {
                    "IPAMConfig": {},
                    "Links": null,
                    "Aliases": [],
                    "MacAddress": "02:42:ac:12:00:03",
                    "DriverOpts": {},
                    "NetworkID": "02c206fcb9c9ad9f850c5de72758d80649ee27e9780e72235238f38be126f953",
                    "EndpointID": "7a7873b11305a208354097b0a3405aba17c7944ef12f50c7829be94e8560fe6e",
                    "Gateway": "172.18.0.1",
                    "IPAddress": "172.18.0.3",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "DNSNames": [
                        "infallible_clarke",
                        "70b6fbcf8952"
                    ]
                }
            }
        }
    }
]

Com isso será possível ao container ubuntu acessar o container nginx:

root@70b6fbcf8952:/# curl http://nginx
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

Ao criar a rede custo o Docker sugeriu a utilização da sub rede 172.18.0.0/16. Porém se já existir essa sub rede fora da estrutura Docker haverá conflito:

$ docker network inspect custom | grep -Ei "subnet"
                    "Subnet": "172.18.0.0/16",

Especificação manual da sub rede:

~$ docker network create --help

Usage:  docker network create [OPTIONS] NETWORK

Create a network

Options:
      --attachable           Enable manual container attachment
      --aux-address map      Auxiliary IPv4 or IPv6 addresses used by Network driver (default map[])
      --config-from string   The network from which to copy the configuration
      --config-only          Create a configuration only network
  -d, --driver string        Driver to manage the Network (default "bridge")
      --gateway strings      IPv4 or IPv6 Gateway for the master subnet
      --ingress              Create swarm routing-mesh network
      --internal             Restrict external access to the network
      --ip-range strings     Allocate container ip from a sub-range
      --ipam-driver string   IP Address Management Driver (default "default")
      --ipam-opt map         Set IPAM driver specific options (default map[])
      --ipv6                 Enable or disable IPv6 networking
      --label list           Set metadata on a network
  -o, --opt map              Set driver specific options (default map[])
      --scope string         Control the network's scope
      --subnet strings       Subnet in CIDR format that represents a network segment

Utilizar as especificações --subnet e --gateway:

$ docker network create --subnet=10.0.0.0/16 --gateway=10.0.0.1 custom2
5460187d15b4d94021a160f231ab4f8e0aa4ca04bc8915eeaf34cd3cebd05e4e
$ docker network ls
NETWORK ID     NAME      DRIVER    SCOPE
29f83204d89d   bridge    bridge    local
02c206fcb9c9   custom    bridge    local
5460187d15b4   custom2   bridge    local
73f2d51a39de   host      host      local
9198ba9fc6fd   none      null      local
$ docker network inspect custom2 | grep -Ei "subnet|gateway|ipaddress"
                    "Subnet": "10.0.0.0/16",
                    "Gateway": "10.0.0.1"

Conexão dos containers existentes:

$ docker container ls
CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS          PORTS     NAMES
70b6fbcf8952   ubuntu    "/bin/bash"              40 minutes ago   Up 40 minutes             infallible_clarke
dadeac1f8244   nginx     "/docker-entrypoint.…"   41 minutes ago   Up 41 minutes   80/tcp    nginx
$ docker network connect custom2 infallible_clarke
$ docker network disconnect custom infallible_clarke
$ docker container inspect infallible_clarke | grep -Ei "ipaddress|gateway"
            "SecondaryIPAddresses": null,
            "Gateway": "",
            "IPAddress": "",
            "IPv6Gateway": "",
                    "Gateway": "10.0.0.1",
                    "IPAddress": "10.0.0.2",
                    "IPv6Gateway": "",
$ docker network connect custom2 nginx
$ docker network disconnect custom nginx
$ docker container inspect nginx | grep -Ei "ipaddress|gateway"
            "SecondaryIPAddresses": null,
            "Gateway": "",
            "IPAddress": "",
            "IPv6Gateway": "",
                    "Gateway": "10.0.0.1",
                    "IPAddress": "10.0.0.3",
                    "IPv6Gateway": "",

O acesso ao container nginx a partir do ubuntu continua disponível:

root@70b6fbcf8952:/# curl http://nginx
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

Criação de container já especificando a rede a ser conectada. O container nginx continua sendo acessível agora a partir do novo container:

$ docker container run -it --network custom2 ubuntu /bin/bash
root@00775d9f7e89:/# apt update && apt install curl --yes && curl
curl: try 'curl --help' or 'curl --manual' for more information
root@00775d9f7e89:/# curl http://nginx
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

$ docker container inspect serene_goldberg | grep -Ei "subnet|gateway|ipaddress"
            "SecondaryIPAddresses": null,
            "Gateway": "",
            "IPAddress": "",
            "IPv6Gateway": "",
                    "Gateway": "10.0.0.1",
                    "IPAddress": "10.0.0.4",
                    "IPv6Gateway": "",

Criação de container conversao-temperatura na mesma sub rede:

$ docker container run -d --network custom2 marcelodpbarbieri/conversao-temperatura:v1
aebe591402c8dc9cad3528db88f61cfe195a8d0b00df8c0ed5dff63b322f77b1
$ docker container ls
CONTAINER ID   IMAGE                                        COMMAND                  CREATED          STATUS          PORTS     NAMES
aebe591402c8   marcelodpbarbieri/conversao-temperatura:v1   "node server.js"         47 seconds ago   Up 46 seconds             xenodochial_kirch
00775d9f7e89   ubuntu                                       "/bin/bash"              7 minutes ago    Up 7 minutes              serene_goldberg
70b6fbcf8952   ubuntu                                       "/bin/bash"              57 minutes ago   Up 57 minutes             infallible_clarke
dadeac1f8244   nginx                                        "/docker-entrypoint.…"   58 minutes ago   Up 58 minutes   80/tcp    nginx
$ docker container inspect xenodochial_kirch | grep -Ei "network|ipaddress|gateway"
            "NetworkMode": "custom2",
        "NetworkSettings": {
            "SecondaryIPAddresses": null,
            "Gateway": "",
            "IPAddress": "",
            "IPv6Gateway": "",
            "Networks": {
                    "NetworkID": "5460187d15b4d94021a160f231ab4f8e0aa4ca04bc8915eeaf34cd3cebd05e4e",
                    "Gateway": "10.0.0.1",
                    "IPAddress": "10.0.0.5",
                    "IPv6Gateway": "",

Bridges distintas

Existe a possibilidade de criar os container com isolamento de rede, conforme imagem abaixo:

Criação das redes:

$ docker network ls
NETWORK ID     NAME      DRIVER    SCOPE
29f83204d89d   bridge    bridge    local
73f2d51a39de   host      host      local
9198ba9fc6fd   none      null      local
$ docker network create --subnet=10.0.0.0/16 --gateway=10.0.0.1 custom1
9eb5a4ec5d86c38761768055767a8a077f3a290e6ec63791df921d07ed574050
$ docker network create --subnet=20.0.0.0/16 --gateway=20.0.0.1 custom2
aeac0dbaf41fab8360b2a81e50a0ee3d239fd8404c0a6ccc21d6608cf5aa1235
$ docker network ls
NETWORK ID     NAME      DRIVER    SCOPE
29f83204d89d   bridge    bridge    local
9eb5a4ec5d86   custom1   bridge    local
aeac0dbaf41f   custom2   bridge    local
73f2d51a39de   host      host      local
9198ba9fc6fd   none      null      local

Criação dos containers nginx1 e ubuntu1 para a rede custom1, e demonstração do acesso ao container nginx1 e a falta de acesso ao container nginx2:

$ docker container run -d --network custom1 --name nginx1 nginx
911750d6bec5ada5658d76273558bfef99ab50deadbbb9d8dbe86a5f19a65897
$ docker container run -it --network custom1 --name ubuntu1 ubuntu /bin/bash
root@91fa3d41367b:/# apt update && apt install curl --yes
root@91fa3d41367b:/# curl
curl: try 'curl --help' or 'curl --manual' for more information
root@91fa3d41367b:/# curl nginx1
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>
root@91fa3d41367b:/# curl nginx2
curl: (6) Could not resolve host: nginx2

Criação dos containers nginx2 e ubuntu2 para a rede custom2, e demonstração do acesso ao container nginx2 e a falta de acesso ao container nginx1:

$ docker container run -d --network custom2 --name nginx2 nginx
885e750713e13991c0ba77dbfcbfbff9d6e8d69af38864910feef8154946d571
$ docker container run -it --network custom2 --name ubuntu2 ubuntu /bin/bash
root@874701ee0b12:/# apt update && apt install curl --yes
root@874701ee0b12:/# curl
curl: try 'curl --help' or 'curl --manual' for more information
root@874701ee0b12:/# curl nginx2
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>
root@874701ee0b12:/# curl nginx1
curl: (6) Could not resolve host: nginx1

Containers criados:

$ docker container ls
CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS          PORTS     NAMES
874701ee0b12   ubuntu    "/bin/bash"              2 minutes ago    Up 2 minutes              ubuntu2
91fa3d41367b   ubuntu    "/bin/bash"              2 minutes ago    Up 2 minutes              ubuntu1
885e750713e1   nginx     "/docker-entrypoint.…"   11 minutes ago   Up 11 minutes   80/tcp    nginx2
911750d6bec5   nginx     "/docker-entrypoint.…"   11 minutes ago   Up 11 minutes   80/tcp    nginx1

$ docker container ls --format "table {{.ID}}\t{{.Names}}\t{{.Image}}\t{{.Networks}}"
CONTAINER ID   NAMES     IMAGE     NETWORKS
874701ee0b12   ubuntu2   ubuntu    custom2
91fa3d41367b   ubuntu1   ubuntu    custom1
885e750713e1   nginx2    nginx     custom2
911750d6bec5   nginx1    nginx     custom1

Inspeção dos endereços IP dos containers da rede custom1:

$ docker container inspect nginx1 | grep -Ei "ipaddress|gateway|network"
            "NetworkMode": "custom1",
        "NetworkSettings": {
            "SecondaryIPAddresses": null,
            "Gateway": "",
            "IPAddress": "",
            "IPv6Gateway": "",
            "Networks": {
                    "NetworkID": "9eb5a4ec5d86c38761768055767a8a077f3a290e6ec63791df921d07ed574050",
                    "Gateway": "10.0.0.1",
                    "IPAddress": "10.0.0.2",
                    "IPv6Gateway": "",
$ docker container inspect ubuntu1 | grep -Ei "ipaddress|gateway|network"
            "NetworkMode": "custom1",
        "NetworkSettings": {
            "SecondaryIPAddresses": null,
            "Gateway": "",
            "IPAddress": "",
            "IPv6Gateway": "",
            "Networks": {
                    "NetworkID": "9eb5a4ec5d86c38761768055767a8a077f3a290e6ec63791df921d07ed574050",
                    "Gateway": "10.0.0.1",
                    "IPAddress": "10.0.0.3",

Inspeção dos endereços IP dos containers da rede custom2:

$ docker container inspect nginx2 | grep -Ei "ipaddress|gateway|network"
            "NetworkMode": "custom2",
        "NetworkSettings": {
            "SecondaryIPAddresses": null,
            "Gateway": "",
            "IPAddress": "",
            "IPv6Gateway": "",
            "Networks": {
                    "NetworkID": "aeac0dbaf41fab8360b2a81e50a0ee3d239fd8404c0a6ccc21d6608cf5aa1235",
                    "Gateway": "20.0.0.1",
                    "IPAddress": "20.0.0.2",
$ docker container inspect ubuntu2 | grep -Ei "ipaddress|gateway|network"
            "NetworkMode": "custom2",
        "NetworkSettings": {
            "SecondaryIPAddresses": null,
            "Gateway": "",
            "IPAddress": "",
            "IPv6Gateway": "",
            "Networks": {
                    "NetworkID": "aeac0dbaf41fab8360b2a81e50a0ee3d239fd8404c0a6ccc21d6608cf5aa1235",
                    "Gateway": "20.0.0.1",
                    "IPAddress": "20.0.0.3",
                    "IPv6Gateway": "",                    

Alterar endereço IP da rede padrão "bridge"

Para alterar os endereços IP faz-se necessário alterar o arquivo /etc/docker/daemon.json conforme documentação existente no link abaixo:

Bridge network driverDocker Documentation

{
  "bip": "192.168.1.1/24",
  "fixed-cidr": "192.168.1.0/25",
  "mtu": 1500,
  "default-gateway": "192.168.1.254",
  "dns": ["10.20.1.2","10.20.1.3"]
}

Se o arquivo não existir, deve ser criado.