Use user-defined bridge networks

Docker for DevOps engineer May 27, 2021 7 minute read

Hai semuanya, sebelumnya kita udah mempelajari tentang default bridge network selanjutnya kita bahas tentang user-defined bridge network, Diantaranya meliputi:

Management Docker Network
Create multiple containers in same user-defined bridge network and how to connected each other
Cleanup

Management Docker Network

Untuk me-manage Docker Network kita bisa menggunakan perintah docker network COMMAND. Untuk lebih detailnya kita bisa lihat dokumentasinya.

Jika dijalankan maka hasilnya seperti berikut:

➜ ~  docker network --help

Usage:  docker network COMMAND

Manage networks

Commands:
  connect     Connect a container to a network
  create      Create a network
  disconnect  Disconnect a container from a network
  inspect     Display detailed information on one or more networks
  ls          List networks
  prune       Remove all unused networks
  rm          Remove one or more networks

Run 'docker network COMMAND --help' for more information on a command.

Untuk melihat daftar network kita bisa menggunakan perintah

Jika dijalankan maka hasilnya seperti berikut:

➜ ~  docker network ls
NETWORK ID     NAME      DRIVER    SCOPE
a1dd8d92c317   bridge    bridge    local
9b4dac4a1f4a   host      host      local
de6461398e10   none      null      local

Untuk melihat detail dari suatu network, kita bisa menggunakan perintah seperti berikut:

Jika di jalankan maka hasilnya seperti berikut:

➜ ~  docker network inspect bridge host none
[
    {
        "Name": "bridge",
        "Id": "a1dd8d92c317716fefc26c1210a0e1cb280a0f695adeb7b7784effeeef0adec8",
        "Created": "2021-05-26T00:47:45.778658Z",
        "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,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {},
        "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": {}
    },
    {
        "Name": "host",
        "Id": "9b4dac4a1f4a86872ce14166d700a24d3a311a13b9b88df0e84adc76fcf06779",
        "Created": "2021-04-03T10:50:17.4124317Z",
        "Scope": "local",
        "Driver": "host",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": []
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {},
        "Options": {},
        "Labels": {}
    },
    {
        "Name": "none",
        "Id": "de6461398e1002dba5d8d934ec95e77f55de36f3c2dc08a0f982d81eede35e70",
        "Created": "2021-04-03T10:50:17.3972092Z",
        "Scope": "local",
        "Driver": "null",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": []
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {},
        "Options": {},
        "Labels": {}
    }
]

Dari daftar network tersebut, yang dibuat oleh docker ketika kita meng-install Docker Engine. kita tidak bisa menghapus default atau pre-defined network.

Ok, sekarang untuk mencoba user-defined bridge network. Kita akan buat network dengan perintah seperti berikut:

For Bash script:

For Powershell script:

Jika dijalankan maka hasilnya seperti berikut:

➜ ~  docker network create backend_bridge `
>> --driver bridge
08ef47d6ea7a0011da3d85138e20e4a03f79bbf81b2bbc1433f8561136d4c672

➜ ~  docker network ls -f 'driver=bridge'
NETWORK ID     NAME             DRIVER    SCOPE
08ef47d6ea7a   backend_bridge   bridge    local
a1dd8d92c317   bridge           bridge    local

~  docker network inspect backend_bridge bridge -f '{{ .Name }} -> {{json .IPAM }}'
backend_bridge -> {"Driver":"default","Options":{},"Config":[{"Subnet":"172.21.0.0/16","Gateway":"172.21.0.1"}]}
bridge -> {"Driver":"default","Options":null,"Config":[{"Subnet":"172.17.0.0/16","Gateway":"172.17.0.1"}]}

How to connect containers each other in user-defined bridge network

For Bash script:

For Powershell script:

Jika di jalankan maka hasilnya seperti berikut:

➜ ~  docker container run `
>> --name webapp `
>> -p 8080:80 `
>> --network backend_bridge `
>> -d nginx `
>> | `
>> docker container run `
>> --name postgresdb `
>> -e POSTGRES_PASSWORD=password `
>> -p 5432:5432 `
>> --network backend_bridge `
>> -d postgres:12.6 `
>> | `
>> docker container run `
>> --name centos7 `
>> --network backend_bridge `
>> -it `
>> -d centos:7 bash
c374148946e8c5c073e5c11e0c75c4457f99c7aeaa8bcfdb9572072f8a16032f

➜ ~  docker container ls
CONTAINER ID   IMAGE           COMMAND                  CREATED          STATUS          PORTS                                       NAMES
c374148946e8   centos:7        "bash"                   15 seconds ago   Up 14 seconds                                               centos7
a22ff7c66400   postgres:12.6   "docker-entrypoint.s…"   16 seconds ago   Up 14 seconds   0.0.0.0:5432->5432/tcp, :::5432->5432/tcp   postgresdb
8b756747082e   nginx           "/docker-entrypoint.…"   17 seconds ago   Up 16 seconds   0.0.0.0:8080->80/tcp, :::8080->80/tcp       webapp

➜ ~  docker network inspect bridge backend_bridge --format '{{ .Name }}  ==> {{json .Containers}}'
bridge  ==> {}
backend_bridge  ==> 
{
   "08d9210b39c8f78296a10ab5ea4c00d6a5d705ef689575057a5f3ed960a7a762":{
      "Name":"postgresdb",
      "EndpointID":"8b220c8947d5e6fc4ec5e353963b948a0b815b6c8827ecbfac2341f9139b5b89",
      "MacAddress":"02:42:ac:15:00:03",
      "IPv4Address":"172.21.0.3/16",
      "IPv6Address":""
   },
   "d9a000b91856d10c84de4fd24079241deb7249f152f7f858b9b8f6ca4d9141ac":{
      "Name":"webapp",
      "EndpointID":"411c23b907e75f54be1abe44e961653bc81dfbe9092d8932dfd75e2317ea89df",
      "MacAddress":"02:42:ac:15:00:04",
      "IPv4Address":"172.21.0.4/16",
      "IPv6Address":""
   },
   "e4f9e041acf0a89c44f1849e55d4b55bee86d628822b2c099470709b1163a4dd":{
      "Name":"centos7",
      "EndpointID":"7c345d7dc17c76dc1c8d4bf32ee05f6a2b8064d0568ed058c8ecc089454b2d5e",
      "MacAddress":"02:42:ac:15:00:02",
      "IPv4Address":"172.21.0.2/16",
      "IPv6Address":""
   }
}

Berbeda dengan default bridge network, pada user-defined bridge network jika suatu container mau komumikasi antara container maka kita bisa panggil dengan Internal IP-Address atau Container Name. Ok kita coba berikut schenarionya:

➜ ~  docker exec -it centos7 bash
[root@e4f9e041acf0 /]# ping -c 2 webapp
PING webapp (172.21.0.4) 56(84) bytes of data.
64 bytes from webapp.backend_bridge (172.21.0.4): icmp_seq=1 ttl=64 time=0.030 ms
64 bytes from webapp.backend_bridge (172.21.0.4): icmp_seq=2 ttl=64 time=0.038 ms
--- webapp ping statistics ---

[root@e4f9e041acf0 /]# curl webapp
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    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@e4f9e041acf0 /]# ping -c 2 postgresdb
PING postgresdb (172.21.0.3) 56(84) bytes of data.
64 bytes from postgresdb.backend_bridge (172.21.0.3): icmp_seq=1 ttl=64 time=0.078 ms
64 bytes from postgresdb.backend_bridge (172.21.0.3): icmp_seq=2 ttl=64 time=0.038 ms

--- postgresdb ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1037ms
rtt min/avg/max/mdev = 0.038/0.058/0.078/0.020 ms

[root@e4f9e041acf0 /]# yum install postgresql -y
Installed:
  postgresql.x86_64 0:9.2.24-6.el7_9

[root@e4f9e041acf0 /]# psql -h postgresdb -U postgres -W
Password for user postgres:
psql (9.2.24, server 12.6 (Debian 12.6-1.pgdg100+1))
WARNING: psql version 9.2, server version 12.0.
         Some psql features might not work.
Type "help" for help.

postgres=# \l
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges
-----------+----------+----------+------------+------------+-----------------------
 postgres  | postgres | UTF8     | en_US.utf8 | en_US.utf8 |
 template0 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
 template1 | postgres | UTF8     | en_US.utf8 | en_US.utf8 | =c/postgres          +
           |          |          |            |            | postgres=CTc/postgres
(3 rows)

postgres=# select 1 + 2 as tambah;
 tambah
--------
      3
(1 row)

postgres=# \q
[root@e4f9e041acf0 /]# exit

➜ ~  docker container inspect webapp -f '{{json .NetworkSettings.Networks }}'
{
   "backend_bridge":{
      "IPAMConfig":{
         
      },
      "Links":null,
      "Aliases":[
         "d9a000b91856"
      ],
      "NetworkID":"08ef47d6ea7a0011da3d85138e20e4a03f79bbf81b2bbc1433f8561136d4c672",
      "EndpointID":"3e27239464a83dae36332b327fb72292a1bdcd9190f9fcc06d41685f378cefe7",
      "Gateway":"172.21.0.1",
      "IPAddress":"172.21.0.4",
      "IPPrefixLen":16,
      "IPv6Gateway":"",
      "GlobalIPv6Address":"",
      "GlobalIPv6PrefixLen":0,
      "MacAddress":"02:42:ac:15:00:04",
      "DriverOpts":{
         
      }
   }
}

➜ ~  docker network disconnect backend_bridge webapp

➜ ~  docker network inspect backend_bridge --format '{{json .Containers }}'
{
   "08d9210b39c8f78296a10ab5ea4c00d6a5d705ef689575057a5f3ed960a7a762":{
      "Name":"postgresdb",
      "EndpointID":"8b220c8947d5e6fc4ec5e353963b948a0b815b6c8827ecbfac2341f9139b5b89",
      "MacAddress":"02:42:ac:15:00:03",
      "IPv4Address":"172.21.0.3/16",
      "IPv6Address":""
   },
   "e4f9e041acf0a89c44f1849e55d4b55bee86d628822b2c099470709b1163a4dd":{
      "Name":"centos7",
      "EndpointID":"7c345d7dc17c76dc1c8d4bf32ee05f6a2b8064d0568ed058c8ecc089454b2d5e",
      "MacAddress":"02:42:ac:15:00:02",
      "IPv4Address":"172.21.0.2/16",
      "IPv6Address":""
   }
}

➜ ~  docker container inspect webapp -f '{{json .NetworkSettings.Networks }}'
{}

➜ ~  docker exec -it centos7 bash
[root@e4f9e041acf0 /]# ping -c 2 webapp
ping: webapp: Name or service not known

[root@e4f9e041acf0 /]# curl webapp
curl: (6) Could not resolve host: webapp; Unknown error

➜ ~  docker exec -it centos7 bash
[root@e4f9e041acf0 /]# ping -c 2 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=37 time=22.1 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=37 time=21.6 ms

--- 8.8.8.8 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms

[root@e4f9e041acf0 /]# exit

Cleanup

Setelah kita mencoba, saatnya kita bersih-bersih dulu. Berikut adalah perintahnya:

For Bash script:

For Powershell script:

the conclusion

Bridge networks are isolated networks on a single Engine installation. Differences between user-defined bridges and the default bridge:

User-defined bridges provide automatic DNS resolution between containers.
User-defined bridges provide better isolation.
Containers can be attached and detached from user-defined networks on the fly.
Each user-defined network creates a configurable bridge.

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Dimas Maryanto

Use user-defined bridge networks

Management Docker Network

How to connect containers each other in user-defined bridge network

Cleanup

the conclusion

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