DevOps Classroomnotes 24/Nov/2022

Docker Networking Contd…

• Docker has created a standard CNM (Container Networking Model). Core OS has developed one more standard CNI (Container Networking Interface).
• Networking Articles:
  • Refer Here for series 1
  • Refer Here for swarm
  • Refer Here for series 2
• Docker’s implementation of CNM is libnetwork.
• Refer Here as this is what we are doing now

Experiments

• Lets see the networks available in the docker host
  
• Now lets create two alpine containers d1 and d2
  
• bridge is the default network so lets inspect that

$ docker network inspect bridge
[
    {
        "Name": "bridge",
        "Id": "e71220fbddbfb121ba7607584d225d4bd9830d52ed0f1dea3db54564a53d690e",
        "Created": "2022-11-24T03:05:41.118857844Z",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": [
                {
                    "Subnet": "172.17.0.0/16"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "89359727c19cca0e02fe8ea9f658710286342a58783797fb8bba74590b7b6b2a": {
                "Name": "d1",
                "EndpointID": "20ddb68305cbf23f66b51d128fdf68223ba3813024568397eafb6a6cc0bf9365",
                "MacAddress": "02:42:ac:11:00:02",
                "IPv4Address": "172.17.0.2/16",
                "IPv6Address": ""
            },
            "e0eb0287a9c35f9d101515c6ea88c2401479ff786b700e31f76d0f891c044cce": {
                "Name": "d2",
                "EndpointID": "f89b91e2cc6587ba621304bbc163d6fb1a9121dc3861c996c8c357ab58aec858",
                "MacAddress": "02:42:ac:11:00:03",
                "IPv4Address": "172.17.0.3/16",
                "IPv6Address": ""
            }
        },
        "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": {}
    }
]

• d1 has an ip 172.17.0.2 and d2 has an ip 172.17.0.3
• Lets run ping from d1 to d2 using name and then ip
  
• In default bridge network we are able to ping containers by its ip address
• Now lets try to create our bridge network my_bridge
  
• Now lets create two containers m1 and m2
  
• Inspect the bridge network

[
    {
        "Name": "my_bridge",
        "Id": "90b8b0d2ea383f8fa1f25507418b71296249327b5e23e4d86a0784973ea1a126",
        "Created": "2022-11-24T03:20:11.297771156Z",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "Config": [
                {
                    "Subnet": "10.10.10.0/24"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "53594ba2567529554bf7501b953f8fcd61a69a661df83d9290ba8528354be53f": {
                "Name": "m1",
                "EndpointID": "0fc70a57dec727ff231469fd61da4dbfb56d7bc29d2e13f4408f5277d7b5df62",
                "MacAddress": "02:42:0a:0a:0a:02",
                "IPv4Address": "10.10.10.2/24",
                "IPv6Address": ""
            },
            "968db46fd2dc488ef2a758fe99b2717aa74c5b76a1eef643842a081511b5c25e": {
                "Name": "m2",
                "EndpointID": "bbde38feb3130f99f0e3566a51fba55bd3fad7428dbb63295ef4feeec45c29d8",
                "MacAddress": "02:42:0a:0a:0a:03",
                "IPv4Address": "10.10.10.3/24",
                "IPv6Address": ""
            }
        },
        "Options": {},
        "Labels": {}
    }
]

• Lets ping from m1 to m2 using name i.e. service discovery using DNS and then by ip
  
• The network which we created is user defined bridge network
• Containers can be disconnected from their original network and connected to new network. In the below example i’m connecting d1 from default brige to my_bridge
  
  
• disconnect can be used to move the container back to its parent network.