Why Docker improves development workflow - See It in Action

Why Docker improves development workflow

📖 Scenario: You are a developer working on a simple web application. You want to make sure your app runs the same way on your computer and on your teammate's computer. You also want to avoid installing many software packages manually.

🎯 Goal: Learn how to use Docker to create a container that runs your web app consistently everywhere. You will create a Dockerfile, build an image, and run a container.

📋 What You'll Learn

Create a Dockerfile with a base image

Add commands to copy app files and install dependencies

Build a Docker image with a specific name

Run a Docker container from the image exposing the correct port

💡 Why This Matters

🌍 Real World

Developers use Docker to ensure their apps work the same on all machines and servers, saving time and avoiding bugs caused by different setups.

💼 Career

Knowing Docker is essential for modern software development and DevOps roles, as it helps automate deployment and manage environments efficiently.

1

Create a Dockerfile with base image

Create a file named Dockerfile and write a line to use the base image python:3.12-slim.

Docker

# Your code here

Need a hint?

The first line in a Dockerfile usually starts with FROM followed by the base image name.

2

Add commands to copy app files and install dependencies

In the Dockerfile, add lines to copy the current directory files to /app inside the container and set the working directory to /app. Then add a line to install dependencies from requirements.txt using pip.

Docker

FROM python:3.12-slim
# Your code here

Need a hint?

Use COPY to copy files, WORKDIR to set the directory, and RUN to run commands inside the container.

3

Build the Docker image

Use the command docker build -t mywebapp . in the terminal to build a Docker image named mywebapp from the current directory.

Docker

FROM python:3.12-slim
COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt
# Your code here

Need a hint?

Run this command in your terminal, not inside the Dockerfile. It builds the image with the tag mywebapp.

4

Run the Docker container exposing port 5000

Run the command docker run -p 5000:5000 mywebapp to start a container from the mywebapp image and map port 5000 inside the container to port 5000 on your computer.

Docker

FROM python:3.12-slim
COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt
# Command to build image:
docker build -t mywebapp .
# Your code here

Need a hint?

This command runs your app in a container and makes it accessible on your computer's port 5000.