Docker under Linux: How to deploy applications using containerization?

Docker under Linux: How to deploy applications using containerization?

Introduction:
In modern software development, containerization technology has become a very important skill. As one of the most popular containerization platforms currently, Docker is widely used on Linux. This article will introduce how to use Docker to containerize and deploy applications on Linux, and provide relevant code examples.

1. Why use Docker containers?
As the scale and complexity of software continue to grow, the deployment and operation and maintenance of applications become more and more cumbersome. Traditional deployment methods usually require manual configuration of the environment, handling dependencies and other issues, and there may be incompatibilities between different development environments, resulting in differences between development, testing and production environments, increasing the possibility of errors.

Using Docker containers can package applications and their dependencies into an independent container, and ensure consistent running results in different environments. This isolation allows containers to be quickly deployed and replicated on different machines, thereby improving the efficiency of development and deployment.

2. Install Docker
Before starting to use Docker, you first need to install Docker on the Linux system. The installation can be completed through the following steps:

1. Update system software packages:
$ sudo apt-get update

2. Install Docker dependency packages:
$ sudo apt -get install apt-transport-https ca-certificates curl software-properties-common

3. Add Docker’s official GPG key:
$ curl -fsSL https://download.docker.com/ linux/ubuntu/gpg | sudo apt-key add -

4. Add Docker source:
$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com /linux/ubuntu $(lsb_release -cs) stable"

5. Update the package cache and install Docker:
$ sudo apt-get update
$ sudo apt-get install docker-ce

3. Use Docker containers to deploy applications
The following is a simple example that demonstrates how to use Docker containers to deploy a Python-based web application.

1. Create a working directory named app and enter the directory:
$ mkdir app
$ cd app

2. Create a file named Dockerfile, And copy the following content into the file:

FROM python:3.9
COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt
CMD ["python", "app.py"]

3. In the working directory, create a file called requirements.txt and add the Python dependencies required by the application to the file.

4. Create a Python file named app.py in the working directory as the entry point for the web application.

5. Build the Docker image:
$ docker build -t myapp .

6. Run the Docker container:
$ docker run -d -p 8000:8000 myapp

Now, you have successfully deployed a Python-based web application using Docker containers. The application can be accessed in a local browser by visiting http://localhost:8000.

This example is just a simple demonstration. In fact, Docker provides more configuration and management options, such as network settings, volume mounting, container interconnection, etc., which can be configured according to specific needs.

4. Summary
This article introduces how to use Docker containers to deploy applications under Linux and provides corresponding code examples. By using Docker, you can simplify the application deployment process and improve the efficiency and reliability of deployment. I hope this article will be helpful for you to understand and learn Docker containerized deployment applications.

Code example:
Dockerfile content:

FROM python:3.9
COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt
CMD ["python", "app.py"]

requirements.txt content:

flask==1.1.2

app.py content:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return "Hello, Docker!"

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=8000)

The above is the detailed content of Docker under Linux: How to deploy applications using containerization?. For more information, please follow other related articles on the PHP Chinese website!