Docker Containerization Docker Compose and Multi-Container Applications 3

Question 1

Which Docker Compose version 3 feature allows you to store sensitive data like passwords separately from the compose file?

Accepted Answer

secrets

Answer

The secrets top-level key in Compose v3 manages sensitive data, which is mounted as files in the container at /run/secrets/.

Question 2

What does the 'build' key in a Docker Compose service definition specify?

Accepted Answer

The build context and optional Dockerfile for building the service image

Answer

The build key specifies the build context path and optionally a Dockerfile location used to build the service's image.

Question 3

Which command recreates only the services that have changed configuration since the last 'docker compose up'?

Accepted Answer

docker compose up

Answer

Running docker compose up without flags automatically recreates only services whose configuration has changed.

Question 4

How do you override docker-compose.yml values for a specific environment without modifying the base file?

Accepted Answer

Use docker-compose.override.yml or specify -f with an additional compose file

Answer

docker-compose.override.yml is automatically merged with docker-compose.yml, or you can use -f to specify multiple compose files.

Question 5

In a multi-container Compose setup, how does the 'web' service resolve the hostname 'db' to connect to the database service?

Accepted Answer

Via Docker's embedded DNS server resolving service names

Answer

Docker's embedded DNS server automatically resolves service names to container IP addresses within the shared Compose network.

Docker Practice Test