Networking

Networking In Docker

create a docker bridge network

docker network create --driver=bridge --subnet=192.168.1.0/24 --opt "com.docker.network.driver.mtu"="1501" devel0

list all the networks

docker network ls

connect to a network

docker network connect [options] NETWORK CONTAINER

inspect a network

docker network inspect --format="{{.NetworkSettings.Networks.bridge.IPAddress}}" <container-id>

connect to a network

docker network connect --ip=192.168.1.10 <container-1> <container-2>

disconnect from a network

docker network disconnect bridge <container-name>

configure docker for external DNS

docker run -d --name <container-name> <image-name>

configure dns from command line

docker run -d --name <new-name> --dns=8.8.8.8 --dns=8.8.4.4 <image-name>

configure from daemon.json

{ "dns":["8.8.8.8","8.8.4.4"]}

publish a port so that application can be accessed any port

docker run -d --name mycontainer -P <image>:<tag>

publish a port so that application can be accessed externally

docker run -d --name <any-name> --publish 80:80 <image>:<tag>

deploy a container on overlay network

docker network create --driver=overlay --subnet=192.168.1.0/24 <container-name>

inspect a newly created network

docker network inspect <network-name>

create a docker swarm with the newly created network

docker service create --name <new-name> -p 80:80 --network=<network-name> --replicas 3 httpd

Usecase - Bridge (default)

private network internal to host system. All containers implemented on host using Bridge networking can communicate

Usecase - None

absolutely no network access

Usecase - Host

only accessible via underlying host. Access to services can only be provided by exposing container ports to host system

Usecase - Overlay (swarm scoped driver)

allows communication among all docker daemons that are participating in a swarm. (Default mode of swarm communication)

Usecase - Ingress

"- special overlay network that load balances network traffic amongst a given service's working nodes
- maintains list of all IP addresses from nodes that participate in the service and when a request comes in, routes to one of them for indicated service
- provides ""routing mesh"" that allows services to be exposed to the external network without having a replica running on every node in the swarm"

Usecase - Docker Gateway Bridge

port publishing modes

"Host:
- ports are available only on the underlying host system and NOT available for services outside of the host where the instance exists
- controlled by '--mode=host' deployment
Ingress:
- Since it is responsible for 'routing mesh', it makes all published ports available on all hosts participating on cluster"

troubleshoot container & engine logs

"centos: /var/log/messages
ubuntu: /var/log/daemon
cat /var/log/messages | grep [dD]ocker"

container logs

docker container logs <container-name>

container network model

"SEND NC
Sandbox - network stack configuration
Endpoint - interfaces, switches, ports
Network - collection of endpoints that can communicate directly (bridges, VLANs)
Driver -
Network Controller -"

IPAM

Internet Protocol Address Management

Use of IPAM

Network Drivers enable IPAM through DHCP drivers or plugin drivers so that complex implementations support

Traffic Type on DockerEnginer & UCP & DTR

"1. TCP/UDP
2. Inter Process Communication (IPC)
3. API (REST)"

"When a container is connected to multiple networks, its external connectivity is provided via the first non-internal network, in lexical order."

TRUE

Custom network plugins

docker network create --driver weave mynet