What teaches docker containers

Docker Container Tutorial: From Getting Started to Mastery

Docker is an open source containerization platform that can package applications and their dependencies into containers, providing a consistent development and runtime environment so that they can be deployed anywhere local run. Docker's containerization technology has been widely used in DevOps and cloud computing fields, and is also one of the most popular containerization tools today.

In this tutorial, we will start with the basics of Docker containers and gradually deepen until we are proficient in the main aspects of Docker containers.

1. Basic knowledge of Docker containers

1. Getting started with Docker containers

Docker has two core concepts: images and containers. An image is a lightweight, read-only template that contains an application and its dependencies. A container is a running instance created based on an image, usually used to run applications or test environments.

Run the container in Docker through the following command:

docker run [OPTIONS] IMAGE [COMMAND] [ARG...]

Among them, OPTIONS represents the options of the container, IMAGE represents the image the container is based on, and COMMAND and ARG represent the commands and parameters to be executed by the container. .

For example, the following command will run a container based on the Ubuntu image in Docker and execute the /bin/bash command:

docker run -it ubuntu /bin/bash

2. View Docker container status

To view the status of the Docker container, please use the following command:

docker ps [OPTIONS]

OPTIONS represents the options of the container list. The options that can be used are:

• -a: Show all Containers, including stopped containers.
• -q: Show only the container ID.
• -l: Display the latest container.
• -n: Display the recently created n containers.

For example, the following command will list running Docker containers:

docker ps

3. Install packages in Docker containers

You can use Dockerfile file to define the software packages that need to be installed in the Docker container environment. A Dockerfile is a text file containing multiple commands and parameters used to build a Docker image. The sample content of the Dockerfile is as follows:

FROM ubuntu:latest
RUN apt-get update && apt-get install -y nginx

The Dockerfile above defines an image based on the Ubuntu Linux distribution and uses the apt-get command to install the nginx package. Then, you can use the following command to build the image:

docker build -t my-nginx-image .

where, my-nginx-image is the name of the image, and "." represents the current directory of the directory where the Dockerfile is located.

2. Advanced applications of Docker containers

1. Extension of Docker containers

Docker containers can be expanded as needed to match higher loads . You can use the following command to create multiple containers:

docker-compose up -d

Among them, the -d option means to run the container as a background process.

2. Enter the Docker container

Sometimes you need to perform some operations in the Docker container, such as checking files, running commands, etc. You can use the following command to enter a running Docker container:

docker exec -it [CONTAINER ID] /bin/bash

where CONTAINER ID represents the ID of the container. For example:

docker exec -it bb0cd62f8cac /bin/bash

3. Develop using Docker containers

You can develop using Docker containers to achieve consistency and reliability in your development environment. You can use the following command to start a container and mount the current directory as a volume into the container:

docker run --rm -it -v $(pwd):/app node:latest /bin/bash

Among them, the -rm option means that the container will be automatically deleted after the container is finished running. The -v option means to mount the current directory ($(pwd)) on the host to the /app directory in the Docker container. node:latest is the Docker image and executes the /bin/bash command.

4. Security of Docker containers

Docker containers can protect applications and systems from malicious attacks while providing better operational security. Here are some suggestions for protecting Docker containers:

• The latest Docker image should be used.
• Containers should run with minimal user rights.
• Containers should be protected with complex passwords.
• Containers and images should be updated regularly to prevent vulnerability attacks.

3. Advanced applications of Docker containers

1. Use Docker Compose for container orchestration

Docker Compose is an orchestration tool for Docker. For managing multiple containers. Docker Compose files can be defined using the following command:

version: '3'
services:
  web:
    build: .
    ports:
      - "5000:5000"
  redis:
    image: "redis:alpine"

where version 3 is the version of the Docker Compose file format. Service defines the services that need to be managed, including web and redis. Among them, web uses the build definition to use the current directory as the build context, and redis uses image to obtain the redis image from Docker Hub.

2. Running Docker containers on Kubernetes

Kubernetes is a popular container orchestration system that automatically manages Docker containers. The following is an example of container orchestration using Kubernetes:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-container
          image: my-image:latest
          ports:
            - containerPort: 8080

This Kubernetes manifest file defines a deployment named "my-deployment" and runs 3 replicas. It also defines a container named "my-container", uses the my-image:latest image, and exposes the service on port 8080.

Conclusion

Docker container technology provides powerful tools for the DevOps and cloud computing fields, providing consistency and reliability during development and operation. In this tutorial, we take an in-depth look at the basics, advanced applications, and advanced applications of Docker containers, and provide practical examples, hoping to help you understand and use this important technology.

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