Robot Resistors Docker Image Repository

Introduction

In this lab, you will step into a futuristic setting at a robot factory where a group of rebellious robots, led by the character "Robot Resistor," has emerged, aiming to challenge the status quo of the factory's operational system. To support the efforts of the factory's management, it is crucial to learn how to push Docker images to a remote repository for efficient image management and distribution.

Skills Graph

Configure Docker Repository

In this step, you will explore the process of configuring a Docker repository to secure and share Docker images. Begin by setting up the necessary configurations for pushing Docker images to the repository.

Environment

• Operating System: Linux
• Default Terminal: zsh
• Default Working Directory: /home/labex/project
• Docker Version: 20.10.21

Instructions

1. Create a Docker repository configuration file named docker-config.json in the ~/project directory with the following content:

{
  "auths": {
    "https://index.docker.io/v1/": {
      "auth": "your-base64-encoded-credentials"
    }
  }
}

Replace "your-base64-encoded-credentials" with your Docker Hub credentials encoded in base64. You can generate this using the following command:

echo -n 'your-docker-hub-username:your-docker-hub-password' | base64

2. If you use a private registry server, replace the content of docker-config.json with the following content:

   {
     "auths": {
       "https://docker-repo.example.com": {
         "username": "your_username",
         "password": "your_password",
         "email": "your_email"
       }
     }
   }

3. Use the following lines to validate the Docker repository configuration:

import json
import os

def check_docker_config_file(file_path):
    try:
        with open(file_path, 'r') as file:
            config_data = json.load(file)
            print("Docker configuration file is valid.")
            return True
    except FileNotFoundError:
        print(f"Error: File not found - {file_path}")
        return False
    except json.JSONDecodeError:
        print(f"Error: Invalid JSON format in file - {file_path}")
        return False
    except Exception as e:
        print(f"Error: {e}")
        return False

## Specify the path to your docker-config.json file
config_file_path = '/home/labex/project/docker-config.json'

## Check the Docker configuration file
if os.path.isfile(config_file_path) and os.access(config_file_path, os.R_OK):
    check_docker_config_file(config_file_path)
else:
    print(f"Error: Unable to read the file - {config_file_path}")

Save the script to a file, for example, check_docker_config.py, and execute it using the following line:

python check_docker_config.py

Build and Tag Docker Image

In this step, you will learn to build and tag a Docker image before pushing it to the repository.

Instructions

1. Build a sample Docker image from the Dockerfile located at ~/project/Dockerfile:

   FROM alpine:latest
   CMD echo "Hello, World!"

2. Build the image:

   docker build -t robot-image:v1 ~/project

3. Tag the newly built Docker image:

   docker tag robot-image:v1 < your-docker-hub-username > /robot-image:v1
   
   ## if you use the private registry server, use following command
   docker tag robot-image:v1 < your-registry-server > /robot-image:v1

4. Check the existence of the tagged Docker image using the following checker script:

   docker images < your-docker-hub-username > /robot-image:v1
   
   ## if you use the private registry server, use following command
   docker images < your-registry-server > /robot-image:v1

Summary

In this lab, you have simulated an environment where managing and distributing Docker images is crucial for maintaining operational efficiency. By configuring a Docker repository, building, tagging, and pushing Docker images, you have gained valuable insights into image management, fostering a deeper understanding of Docker's capabilities and best practices.