You will see that port 80 of the Docker container is bound to the host IP address 0.0.0.0 and host port 32768 (or a different port if you try the command yourself).Exposing all Docker ports is typically not a good idea since the default is to not expose any port at all. But Docker does an outstanding job of providing all the needed documentation.The answer: Docker does not expose ports by default, you have to configure every exposed port yourself!As a developer, some Docker concepts are more difficult to understand than others. Have you ever been to a job interview where they expected you to know how Docker works as a junior developer? You can run it everywhere as long as you’ve got Docker installed.But enough about the advantages of Docker. Well, there are multiple options to do so.
Exposing TCP and UDP Ports Using Dockerfile: In the earlier section of this article, I showed you how to expose a TCP port using a Dockerfile. This article will show you why that is. -i docker0 -p tcp -m tcp --dport 8080 -j DNAT --to-destination 172.17.0.2:80 While launching one it possible to assign with forwarding a port as shown in below figure. And I’ll also explain how port binding works along the way.Even if you are a more seasoned developer, you should know what port binding is. You don’t want to expose everything because that does not make any sense at all, right?To expose just one port, execute the following line:Port 80 of the Nginx container is exposed to the outside world on host port 8080. If you don’t know what a UUID is, read all about it in Now if you try to connect directly to the Docker container using Docker containers can connect to the outside world without any configuration. You can run it on Windows, Linux, or Mac. When doing so, you don’t need to use ports from the ephemeral port range. Just use the command from above followed up with the container UUID. Well, one problem that Docker tried to solve is the installation nightmare.We’ve all been in the situation where you are installing a program on Windows, Mac, or Linux. I'd like to access this host port from within a running container. If we launch a Docker container without expose any port from it toward Docker Host machine,in which we installed some application.
A Docker container contains everything it needs to function and nothing more. That’s great because we don’t have to change anything we have programmed before.But the outside world cannot connect to a Docker container by default.Ah, I see. I can access the port 8080 of my www Docker container. To allow communication via the defined ports to containers outside of the same network,you need to publish the ports by using -p flag on docker run to publish and map one or more ports, or the -P flag to publish all exposed ports and map them to high-order ports. Usually Docker uses the default 172.17. By default, the container is assigned an IP address for every Docker network it connects to. A port can be exposed either using the --expose flag when running docker run or by using the EXPOSE command in a Dockerfile. And each network is created with a default subnet mask, using it as a pool later on to give away the IP addresses. Voila! I’ll show you the result of the curl command.Let me also show you how this would look in your browser if you visited 0.0.0.0:8080.By default, Docker exposes container ports to the IP address 0.0.0.0 (this matches any IP on the system).