#Docker entrypoint code

Next, we have the CMD directive that provides the default command (), which will be executed when a container is created from the custom Docker image (which we have not created yet).

The parent image will be downloaded from Docker Hub, a cloud-based storage location for Docker images. The FROM directive is followed by the argument alpine, which is the parent image that our custom image is going to be built on top of. In our case, we have two directives: FROM and CMD. Note that it’s a good practice to write the directives in UPPERCASE to distinguish them from the arguments. Each instruction consists of a directive followed by an argument. In this Dockerfile, we have two instructions.

#Docker entrypoint code

Next, copy and paste the following code into the Dockerfile. You can choose any name you prefer for the directory but the file must be named Dockerfile. Inside this directory, create a file called Dockerfile. To follow along, open your code editor and create a directory named docker-demo. Let’s take a closer look at what CMD does inside a Dockerfile by diving into an example. If you don’t have Docker Desktop, you can download it from the link: Get Docker. You also need to have Docker Desktop installed and running on your system. To follow along with the examples in this post, you need a code editor. In this blog post, we’ll explore CMD and ENTRYPOINT, figure out what they do, understand the key difference between them, and most importantly learn when to use which. CMD and ENTRYPOINT are two such directives. Each instruction is composed of a directive and an argument. A Dockerfile is a text file that contains instructions that are executed by Docker to create the Docker image. Before we can run an application inside a container, we must create a Docker image of the application using Dockerfiles. Docker is a platform that lets us run and manage applications inside containers.