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docker build

Learn to build an image from a Dockerfile with docker build.

docker build

docker build produces an image from a Dockerfile. The last argument is the build context: the folder sent to Docker (usually .). -t names the image:

$ docker build -t api:1.0 .
[+] Building 6.3s (10/10) FINISHED
 => [1/4] FROM docker.io/library/python:3.12-slim
 => [2/4] WORKDIR /app
 => [3/4] COPY . .
 => naming to docker.io/library/api:1.0 done

If the Dockerfile has a different name or location it is given with -f: docker build -f docker/Dockerfile.prod -t api:prod .

After the build

The produced image stays in the local store; it is seen with docker images and can be run directly. If you rebuild with the same tag as you change the code, the old image is left untagged (<none>):

$ docker images api
REPOSITORY   TAG       IMAGE ID       CREATED          SIZE
api          1.0       4f1e2d3c4b5a   10 seconds ago   162MB
$ docker run --rm api:1.0

Practice Build and run

Write two commands that build the api:1.0 image from the Dockerfile in the current folder, then run it as a container that is deleted when done.

Starter code

terminal
# buraya yaz

Sample solution

terminal
docker build -t api:1.0 .
docker run --rm api:1.0

Expected output

[+] Building 6.3s (10/10) FINISHED
 => naming to docker.io/library/api:1.0 done
 * Running on http://0.0.0.0:8000

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What does the dot in docker build -t api:1.0 . specify?

  • The image name
  • The tag
  • The Dockerfile content
  • The current folder as the build context Correct answer

Explanation: COPY can only access files inside the context.

2 Use a different Dockerfile.

Question 
docker build ____ Dockerfile.prod -t api:prod .
Answer 
docker build -f Dockerfile.prod -t api:prod .

Explanation: -f (file) gives the Dockerfile path.

3 Match.

Term Meaning
-t Image name and tag
. Build context
-f Dockerfile path
<none> Old image whose tag was taken

All lessons in Beginner

1 What is Docker?

  1. What is Docker?
  2. Containers and virtual machines
  3. Images and containers
  4. Docker architecture
  5. Use cases
  6. Summary - What is Docker

2 Installation and first commands

  1. Installing Docker
  2. docker version
  3. docker info
  4. The hello-world container
  5. Docker Desktop
  6. Summary - Installation

3 First container

  1. docker run basics
  2. Running in the background
  3. docker ps
  4. docker stop and rm
  5. docker logs
  6. Summary - First container

4 Dockerfile basics

  1. What is a Dockerfile?
  2. The FROM instruction
  3. The RUN instruction
  4. COPY and ADD
  5. CMD and ENTRYPOINT
  6. Summary - Dockerfile

5 Build and images

  1. docker build
  2. Tagging images
  3. Build context
  4. Layers and cache
  5. .dockerignore
  6. Summary - Build

6 docker run options

  1. Interactive mode
  2. Naming containers
  3. Restart policy
  4. Working directory
  5. Switching users
  6. Summary - docker run

7 Image management

  1. docker images
  2. docker rmi
  3. docker pull
  4. docker push
  5. docker tag
  6. Summary - Image management

8 Port mapping

  1. The port concept
  2. The -p flag
  3. Multiple ports
  4. Random ports
  5. IP binding
  6. Summary - Port mapping

9 Volumes and data

  1. Data persistence
  2. Named volumes
  3. The -v flag
  4. Bind mounts
  5. Volume management
  6. Summary - Volumes

10 Environment variables

  1. The -e flag
  2. The ENV instruction
  3. The ARG instruction
  4. env-file
  5. The WORKDIR instruction
  6. Summary - Environment

11 Project: docker-compose

  1. Compose design
  2. Service definition
  3. Database service
  4. Volume and network
  5. Putting it together - compose

12 Docker Hub and registry

  1. What is Docker Hub?
  2. docker login
  3. Searching images
  4. Official images
  5. Private registry
  6. Summary - Registry

13 Network basics

  1. Network drivers
  2. docker network ls
  3. Bridge network
  4. Container connectivity
  5. Publishing ports
  6. Summary - Network

14 Beginner final

  1. Challenge - Dockerfile
  2. Challenge - Build and run
  3. Challenge - Volume
  4. Challenge - Compose
  5. Challenge - Beginner project