COPY instruction for adding files in Docker - Mini Project: Build & Apply

Using COPY Instruction to Add Files in Docker

📖 Scenario: You are creating a Docker image for a simple web application. You need to add your application files into the image so it can run inside a container.

🎯 Goal: Learn how to use the COPY instruction in a Dockerfile to add files from your local machine into the Docker image.

📋 What You'll Learn

Create a Dockerfile with a base image

Use the COPY instruction to add files

Verify the files are added inside the image

💡 Why This Matters

🌍 Real World

Adding application files into Docker images is a common step to package software for deployment.

💼 Career

Understanding COPY is essential for creating Docker images in DevOps and software development roles.

1

Create a Dockerfile with a base image

Create a file named Dockerfile and write the line FROM alpine:latest to set the base image.

Docker

# Create a Dockerfile with the base image alpine:latest
# Your code here

Need a hint?

The FROM instruction sets the base image for your Docker image.

2

Add a sample file to copy

Create a file named app.txt in the same folder as your Dockerfile with the content Hello from Docker!.

Docker

FROM alpine:latest
# Create a file named app.txt with the text 'Hello from Docker!'
# Your code here

Need a hint?

This step is done outside the Dockerfile by creating a text file in your project folder.

3

Use COPY instruction to add the file

Add the line COPY app.txt /app/app.txt to your Dockerfile to copy app.txt from your local folder into the image at /app/app.txt.

Docker

FROM alpine:latest
COPY app.txt /app/app.txt
# Your code here

Need a hint?

The COPY instruction copies files from your local folder into the image.

4

Verify the file inside the image

Add the line RUN cat /app/app.txt to your Dockerfile to print the content of the copied file when building the image.

Docker

FROM alpine:latest
COPY app.txt /app/app.txt
# Your code here

Need a hint?

The RUN instruction runs commands inside the image during build time.