How to make your own docker image file

Docker is an open source application container engine that allows developers to package applications into an image and run it anywhere. Today, this article will introduce how to make your own docker image file so that you can better manage your applications.

1. Install Docker

First, you need to install Docker on your computer. Docker is available on Linux, macOS and Windows operating systems. Please download and install Docker according to your operating system.

2. Write the Dockerfile

Next, you need to write the Dockerfile. A Dockerfile is a text file that describes how to build a docker image. For beginners, it may feel a little complicated. However, once you understand the syntax and components of a Dockerfile, it will become easier.

In your working directory, create a text file and name it Dockerfile. Then open the Dockerfile with a text editor and start editing. The main components of the Dockerfile are as follows:

1. FROM: Specify the required base image.
2. RUN: Command executed within the container.
3. COPY: Copy local files to the container.
4. WORKDIR: Set the working directory.
5. CMD: Command executed when the container starts.

For example, the following is a simple Dockerfile:

FROM ubuntu:18.04
RUN apt-get update && \
    apt-get install -y nginx
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

This Dockerfile is based on Ubuntu 18.04 (base image) and installs NGINX in it. Then expose port 80 to the outside and start NGINX when the container starts.

3. Build the image

After you write the Dockerfile, you need to use the Docker command to build it into a usable container image. We can use the following command to build an image named "test-nginx":

docker build -t test-nginx .

In this command, the "-t" parameter is used to specify the name and label of the image, followed by "test-nginx" . The dot indicates that the current directory is the build context. The build context is all files and directories sent to the Docker engine during the build process.

4. Run the container

Now we have successfully created a docker image named "test-nginx". Next, we can use the "docker run" command to run a container based on the image:

docker run -p 80:80 test-nginx

This command will run the "test-nginx" image and map port 80 of the container to port 80 of the host port. Now, you can use your browser to access http://localhost to access your NGINX server.

Summary

Using Docker makes it easier to manage and deploy applications. This article describes how to make your own docker image file, install and run NGINX in it. With Docker, you can build applications of any complexity and deploy them to the cloud, data center, or local computer.

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