This assumes you have installed Docker on Linux and Docker is running.

A Docker image contains the code used to create a Docker container, such as creating a Nginx web server, or a mySQL server, or a home grown app, and the list goes on. In this way, an image is like a template used to create a container. An image is kind of like a virtual machine, but much more light weight, using significantly less storage a memory (containers are usually megabytes in size).

At a high level, there are a few different ways to run a command in a Docker container.

• CMD in Dockerfile
• Uing the docker exec command
• Using the docker run command (this article)

In this example, I create a NodeJS container using the docker run command and append npm start at the end of the command to run the npm start command in the container.

~]$ sudo docker run --name my-nodejs-container --publish 0.0.0.0:8888:8888 --detach --volume my-nodejs-image:latest npm start