Docker Containerization Docker Compose and Multi-Container Applications

Question 1

What is the primary purpose of Docker Compose?

Accepted Answer

Define and run multi-container Docker applications using a single YAML file

Answer

Build Docker images faster than the standard Dockerfile

Answer

Replace Kubernetes for production deployments

Answer

Manage Docker registries and image versions

Question 2

What command starts all services defined in a docker-compose.yml file in detached mode?

Accepted Answer

docker compose up -d

Answer

docker compose start --background

Answer

docker compose run -d all

Answer

docker compose launch

Question 3

How do you stop and remove all containers, networks, and default volumes created by Docker Compose?

Accepted Answer

docker compose down

Answer

docker compose stop

Answer

docker compose rm

Answer

docker compose kill

Question 4

In a docker-compose.yml file, what does the 'depends_on' key control?

Accepted Answer

The startup order of services, ensuring dependencies start before the dependent service

Answer

Which services share the same network

Answer

Which services share environment variables

Answer

Resource allocation between services

Question 5

What Compose file keyword defines environment variables for a service?

Accepted Answer

environment

Answer

env_vars

Answer

variables

Answer

env

Question 6

What does the 'volumes' key in a service definition do in Docker Compose?

Accepted Answer

Mounts host paths or named volumes into the container's filesystem

Answer

Creates Docker images from directories

Answer

Defines shared memory between containers

Answer

Specifies which containers can write to the same network

Question 7

How does Docker Compose name containers by default?

Accepted Answer

projectname-servicename-number (e.g., myapp-web-1)

Answer

servicename_container_number

Answer

random generated names like in docker run

Answer

servicename only (no project prefix)

Question 8

What is the purpose of the 'build' key in a Docker Compose service definition?

Accepted Answer

Specifies the build context and Dockerfile location to build an image for the service

Answer

Defines the build order of services

Answer

Triggers a production build process

Answer

Specifies the base image to extend

Question 9

What does 'docker compose logs -f' do?

Accepted Answer

Follows (streams) log output from all running services

Answer

Shows the last 10 log lines from each service

Answer

Writes logs to a file

Answer

Shows only error-level logs

Question 10

What is the purpose of a .env file in a Docker Compose project?

Accepted Answer

Provides default variable values for substitution in the compose file itself

Answer

Sets environment variables inside all containers

Answer

Stores Docker Hub credentials

Answer

Configures Docker daemon settings