Pulling Image From Docker Hub

Docker Hub is a hosted repository service provided by Docker for finding and sharing container images. You can host your own images on Docker Hub, but we will use the official Nginx repository to pull images of Nginx which is an open-source reverse proxy server. An official image on docker has an official image tag.

This repository has all the information regarding the Nginx image and how we can use it. On the top right corner, we see a docker pull command specifying how to pull the image to our computer.

Step 1. Use the command to pull the Nginx image.

$ docker pull nginx

Output:

Running A Container From The Pulled Image:

When we run a container using the docker run command, it does not publish any of its ports to the outside world. To expose our container port to services outside of Docker, or to containers that are not in the same network as our container, use the –publish or -p flag. 

A typical example of –publish flag:

$ docker run -p 8080:80 --name webhost -d nginx

Let us break this command to understand better:

1. Docker run Nginx:  will start the container from the Nginx image.
2. -p 8080:80:  will map TCP port 80 in the container to port 8080 on the Docker host.
3. –name webhost:  will name our container webhost, if not specified docker will give it a random name.
4. -d:  flag will run docker in a detached mode that is,  in the background.

Pre-requisites: Docker 

Docker is a set of platform-as-a-service products that use OS-level virtualization to deliver software in packages called containers. These containers may need to talk to each other or to services outside docker, for this we not only need to run the image but also expose the container’s port and make it accessible by other services or containers which are on a different network.

Note: If you need to run docker as the root user, please remember to prepend sudo to the commands. 

Let us now see how we manage ports in Docker.