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Official images

Learn about official images and their security.

Official images

Official images (Docker Official Images) are images in the library/ namespace maintained together by Docker and the software's developers: nginx, postgres, python, node, redis... They get regular security updates, and their documentation explains the environment variables in detail.

docker run -d -e POSTGRES_PASSWORD=gizli postgres:16      # a documented variable
docker run -d -e MYSQL_ROOT_PASSWORD=gizli mysql:8

Initialization scripts

Database images run the .sql and .sh files in the /docker-entrypoint-initdb.d/ folder on first start. This is the way to create the tables and load sample data automatically; it only runs while the data directory is empty:

docker run -d --name db -e POSTGRES_PASSWORD=gizli \
  -v "$PWD/sema.sql":/docker-entrypoint-initdb.d/01-sema.sql:ro \
  -v pgdata:/var/lib/postgresql/data postgres:16

Practice A database with ready tables

Start a container named db from postgres:16 in the background: POSTGRES_PASSWORD=gizli; mount sema.sql from the current folder ("$PWD/sema.sql") read-only at /docker-entrypoint-initdb.d/01-sema.sql.

Starter code

terminal
# buraya yaz

Expected output

c5d6e7f8091a

Questions and answers

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

1 In official image tags, what do suffixes like -slim, -alpine, -bookworm indicate?

  • Processor speed
  • The base operating system and size variant Correct answer
  • The license
  • The release date

Explanation: bookworm is the code name of Debian 12.

2 Mount the initialization script into the right folder.

Question 
-v "$PWD/sema.sql":/____/01-sema.sql:ro
Answer 
-v "$PWD/sema.sql":/docker-entrypoint-initdb.d/01-sema.sql:ro

Explanation: Files in this folder run in name order.

3 Match.

Term Meaning
postgres POSTGRES_PASSWORD
mysql MYSQL_ROOT_PASSWORD
initdb.d First-start scripts
bookworm Debian 12

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