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Docker Basics and Application Deployment Guide

Overview

Note

This guide assumes a basic understanding of Docker and assumes you have Docker Desktop installed on your Windows machine.

Abstract

Docker is a containerization platform that enables developers to package applications and their dependencies into isolated environments called containers. These containers are lightweight, portable, and consistent across development, staging, and production environments.

Docker Desktop Link: https://www.docker.com/products/docker-desktop

Docker Container Work Flow Figure: Comparison between Docker Containers and Virtual Machines

This document provides a comprehensive guide to Docker fundamentals and walks through the process of deploying a Python-based Dash data visualization application using Docker on a local Windows environment.

Core Concepts

  • Image: A static snapshot that contains all the files, environment variables, and configuration needed to run an application.
  • Container: A running instance of a Docker image.
  • Dockerfile: A script containing a set of instructions to assemble a Docker image.
  • Volume: A mechanism for persistent data storage used by containers.
  • Docker Hub: The default public registry for sharing Docker images.

Essential Docker Commands

System Info and Help

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docker --version                # Display Docker version
docker info                    # Display system-wide information
docker help                    # Show help for Docker CLI

Image Management

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docker pull <image>            # Download image from Docker Hub
docker build -t myimage .      # Build image from Dockerfile in current directory
docker images                  # List local images
docker rmi <image_id>          # Delete a local image

Container Lifecycle

Tip

Always stop containers before removing them to avoid data loss. 

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docker run -d -p 8050:8050 myimage   # Run a container in detached mode with port mapping
docker run -d --name my-container -p 8050:8050 myimage   # Run a container in detached mode with port mapping and name
docker ps                            # List running containers
docker ps -a                         # List all containers
docker stop <container_id>          # Stop a container
docker rm <container_id>            # Remove a container
docker stop my-container            # Stop a container by name

Utilities

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docker exec -it <container_id> /bin/bash  # Start an interactive shell in the container
docker logs <container_id>               # View stdout/stderr logs

Example: Deploying a Dash App Using Docker

Example

This section demonstrates how to containerize and run a Dash data visualization application.

Directory Structure

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dash-app/
├── app.py
├── requirements.txt
└── Dockerfile

app.py

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import dash
from dash import html

app = dash.Dash(__name__)
app.layout = html.Div(children=[html.H1("Hello from Dockerized Dash")])

if __name__ == '__main__':
    app.run_server(host='0.0.0.0', port=8050)

requirements.txt

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dash

Dockerfile

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# 使用官方 Python 镜像
FROM python:3.10-slim

# 设置容器内工作目录
WORKDIR /app

# 复制所有文件到容器中
COPY . .

# 安装依赖
RUN pip install --no-cache-dir -r requirements.txt   # requirements.txt contain Dash 依赖项和gunicorn(for docker container)

# 加载 .env 文件
ENV PYTHONUNBUFFERED=1

# 预定义端口
EXPOSE 8050

# 启动命令
CMD ["gunicorn", "app:server", "--bind", "0.0.0.0:8050", "--workers", "1"]

Build and Run Workflow

Step 1: Build the Docker Image

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cd dash-app
docker build -t dash-container .

Step 2: Run the Container

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docker run -d --name dash-app -p 8050:8050 --restart=always dash-container
  • --name gives the container a human-readable name
  • -p maps port 8050 of the container to the host
  • --restart=always ensures the container restarts on reboot

Step 3: Verify Application Availability

Open a browser and navigate to:

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http://localhost:8050

You should see the Dash UI indicating successful deployment.

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# How to check info of a running container in docker

docker ps -a # List all containers, including stopped ones

docker inspect <container_id> # Display detailed information about a container

docker logs <container_id> # View the logs of a container

Best Practices

  • Use .dockerignore to exclude unnecessary files from your image build context
  • Pin versions in requirements.txt to ensure deterministic builds
  • Use tagged images (e.g., myapp:1.0) for version tracking
  • Clean up unused images and containers using docker system prune
  • Use Docker Compose for multi-container applications

Summary

Docker is a powerful and versatile tool that simplifies application deployment by encapsulating runtime environments. By following the practices outlined in this guide, developers can reliably package and deploy Dash or any other web application across systems with consistent behavior and minimal configuration.