docker-networking

I'm a little bit beginner to Docker. I couldn't find any clear description of what this option does in docker run command in deep and bit confused about it. Can we use it to access the applications running on docker containers without specifying a port? As an example if I run a webapp deployed via a docker image in port 8080 by using option -p 8080:8080 in docker run command, I know I will have to access it on 8080 port on Docker containers ip /theWebAppName. But I cannot really think of a way how --net=host option works. After the docker installation you have 3 networks by default: docker

I'm learning docker. I see those two terms make me confuse. For example here is a docker-compose that defined two services redis and web-app . services: redis: container_name: redis image: redis:latest ports: - "6379:6379" networks: - lognet app: container_name: web-app build: context: . dockerfile: Dockerfile ports: - "3000:3000" volumes: - ".:/webapp" links: - redis networks: - lognet networks: lognet: driver: bridge This docker-compose file defines a bridge network named lognet and all services will connect to this network. As I understand, this action makes those services can see others.

So I have 3 ports that should be exposed to the machine's interface. Is it possible to do this with a Docker container? Tania Ang To expose just one port, this is what you need to do: docker run -p <host_port>:<container_port> To expose multiple ports, simply provide multiple -p arguments: docker run -p <host_port1>:<container_port1> -p <host_port2>:<container_port2> Step1 In your Dockerfile , you can use the verb EXPOSE to expose multiple ports. e.g. EXPOSE 3000 80 443 22 Step2 You then would like to build an new image based on above Dockerfile . e.g. docker build -t foo:tag . Step3 Then you

I have a situation to restrict internet access of the container in load balancer network. for example in that below picture Only container4 connects to the Internet; other three only communicate through container4 with the outside world. For example if container1 needs smtp support, it will forward smtp request to container4 to get access. No container other than container4 should be allowed to access the Internet directly! This should be enforced on Docker level. I believe it will be configurable on docker network creation , can any one explain how to achieve this? Bilal Usean Network