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Build an Image

When to Use This Guide

Use this guide when you have a Dockerfile and want to build it into an image you can run or share.

Quick Command

docker build -t my-app .

Step 1: Build the Image

Run this from the folder that contains your Dockerfile.

docker build -t my-app .
  • -t my-app names (tags) the image
  • the . is the build context: the current folder

Step 2: Confirm It Was Created

docker images my-app

You should see my-app listed with a size and image ID.

Step 3: Run It

docker run -d -p 8000:5000 --name app my-app

Common Issues

"failed to read dockerfile"

You are not in the folder containing the Dockerfile, or the file is not named exactly Dockerfile. Check with ls.

Build is slow every time

Copy dependency files and install them before copying your code, so Docker can reuse cached layers.