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

Exercise 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.

Test yourself

In official image tags, what do suffixes like -slim, -alpine, -bookworm indicate?
- Processor speed
- The base operating system and size variant
- The license
- The release date
Show answer

The base operating system and size variant — bookworm is the code name of Debian 12.

Mount the initialization script into the right folder.

-v "$PWD/sema.sql":/____/01-sema.sql:ro

Show answer

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

Match.

postgres

POSTGRES_PASSWORD
mysql

MYSQL_ROOT_PASSWORD
initdb.d

First-start scripts
bookworm

Debian 12

Next lesson: Private registry

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