Using Bridge Network in Docker

Table of Contents

Dalam istilah Docker, bridge digunakan agar memungkinkan containers yang terhubung dalam network bridge yang sama untuk berkomunikasi, sekaligus mengisolasi dari containers lain yang tidak terhubung ke network bridge tersebut.

Docker bridge driver secara otomatis menginstal aturan di mesin host sehingga containers pada network bridge yang berbeda tidak dapat berkomunikasi secara langsung satu sama lain

Use the default bridge network
#

Buat 2 containers menggunaka image alpine untuk pengujian network bridge

docker run -dit --name alpine1 alpine ash
docker run -dit --name alpine2 alpine ash

Cek untuk memastikan containers sudah berjalan

docker container ls

CONTAINER ID   IMAGE     COMMAND   CREATED          STATUS         PORTS     NAMES
e8960d257fea   alpine    "ash"     7 seconds ago    Up 6 seconds             alpine2
3674b7e97db3   alpine    "ash"     10 seconds ago   Up 8 seconds             alpine1

Inspect network bridge untuk melihat containers yang telah terhubung

docker network inspect bridge

...
{
  "3674b7e97db3d2e3709498bc2b381c118d163c1d93492f93a898cffdab555d64": {
    "Name": "alpine1",
    "EndpointID": "8b8f8e59285714296d1d3ce40ee5f7c7ad8db1e4805e16e61d12b3bcd32271e5",
    "MacAddress": "02:42:ac:11:00:02",
    "IPv4Address": "172.17.0.2/16",
    "IPv6Address": ""
  },
  "e8960d257fea38ee7827e7245fe1a3596e065a83018c52feaa28bea8490e6068": {
    "Name": "alpine2",
    "EndpointID": "29970c6b62c082038d8c8a6e5f28dba6bf88058a3b826e7769fe88870fc6ede9",
    "MacAddress": "02:42:ac:11:00:03",
    "IPv4Address": "172.17.0.3/16",
    "IPv6Address": ""
  }
}
...

Masuk ke shell pada containers alpine1 lalu coba ping IP container alpine2.

docker exec -it alpine1 sh

/ # ping -c4 172.17.0.3
PING 172.17.0.3 (172.17.0.3): 56 data bytes
64 bytes from 172.17.0.3: seq=0 ttl=64 time=0.152 ms
64 bytes from 172.17.0.3: seq=1 ttl=64 time=0.097 ms
64 bytes from 172.17.0.3: seq=2 ttl=64 time=0.087 ms
64 bytes from 172.17.0.3: seq=3 ttl=64 time=0.107 ms

Output diatas menandakan bahwa containers berhasil terhubung ke network bridge yang sama.

Sekarang coba test ping menggunakan nama containers

/ # ping -c4 alpine2
ping: bad address 'alpine2'

Test ping dengan nama containers tidak berhasil terhubung

Exit shell alpine1 CTRL+D

Stop dan remove containers

docker stop alpine1 alpine2
docker rm alpine1 alpine2

Use user-defined bridge networks
#

Buat network bridge dengan nama net-priv

docker network create --driver bridge net-priv

List network

docker network ls

NETWORK ID     NAME       DRIVER    SCOPE
a348ab0b6139   bridge     bridge    local
c066dfd4012a   host       host      local
4bef5690ba4e   net-priv   bridge    local
266a0a91f950   none       null      local

Selanjutnya buat 3 containers dengan topologi berikut.

flowchart TD
A(net-priv)
A o--o B[alpine1]
A o--o C[alpine2]

D(bridge)
D o--o E[alpine3]

docker run -dit --name alpine1 --network net-priv alpine ash
docker run -dit --name alpine2 --network net-priv alpine ash
docker run -dit --name alpine3 alpine ash

Inspect network net-priv

docker network inspect net-priv | jq '.[].Containers'

{
  "394332126aedc7bca965499c853511236dd4bc0f626db25fcffd004466e89dc8": {
    "Name": "alpine1",
    "EndpointID": "c278cac84164596c5e0af8ac28f16fcb88ba64fd3185121cea91a2cec2cfe22d",
    "MacAddress": "02:42:ac:12:00:02",
    "IPv4Address": "172.18.0.2/16",
    "IPv6Address": ""
  },
  "da6d6c97a7b5a7d5ee458095c192b3efb4cadcd7ab6eb3bde2ee7050d91b9ff6": {
    "Name": "alpine2",
    "EndpointID": "64fa8a7830c5585b4ee05e4041e8de013ffd4e63b9c55c828e8a47ae94bea5a7",
    "MacAddress": "02:42:ac:12:00:03",
    "IPv4Address": "172.18.0.3/16",
    "IPv6Address": ""
  }
}

Inspect network bridge

docker network inspect bridge | jq '.[].Containers'

{
  "8f7ad7db3a8794362a009032133b0f7d58576fe417937d78d68a19ad5eee32fe": {
    "Name": "alpine3",
    "EndpointID": "4853296cfe6f730deb7d368217ee886f4d036ff7f610f8192a228477cd6069b9",
    "MacAddress": "02:42:ac:11:00:02",
    "IPv4Address": "172.17.0.2/16",
    "IPv6Address": ""
  }
}

Masuk shell pada containers alpine1 lalu ping ke IP containers alpine2

docker exec -it alpine1 sh

/ # ping -c4 172.18.0.3
PING 172.18.0.3 (172.18.0.3): 56 data bytes
64 bytes from 172.18.0.3: seq=0 ttl=64 time=0.173 ms
64 bytes from 172.18.0.3: seq=1 ttl=64 time=0.109 ms
64 bytes from 172.18.0.3: seq=2 ttl=64 time=0.112 ms
64 bytes from 172.18.0.3: seq=3 ttl=64 time=0.153 ms

Selanjutnya coba ping menggunakan nama containers

/ # ping -c4 alpine2
PING alpine2 (172.18.0.3): 56 data bytes
64 bytes from 172.18.0.3: seq=0 ttl=64 time=0.085 ms
64 bytes from 172.18.0.3: seq=1 ttl=64 time=0.128 ms
64 bytes from 172.18.0.3: seq=2 ttl=64 time=0.084 ms
64 bytes from 172.18.0.3: seq=3 ttl=64 time=0.112 ms

Kedua cara ping berhasil terhubung. Terakhir coba ping dengan IP dan nama containers alpine3

/ # ping -c4 172.17.0.2
PING 172.17.0.2 (172.17.0.2): 56 data bytes
^C
--- 172.17.0.2 ping statistics ---
4 packets transmitted, 0 packets received, 100% packet loss
/ # ping -c4 alpine3
ping: bad address 'alpine3'