What are the top-level sections in a docker-compose.yml file, and what does each do? (Demonstrates familiarity with the file's structure.)

Q: What are the top-level sections in a docker-compose.yml file, and what does each do? (Demonstrates familiarity with the file's structure.)

**Services:** Specifies the containers to run and their runtime configuration (image, build context, ports, environment variables, volumes, depends_on, healthcheck, etc.). **Volumes:** Declares named persistent storage volumes that can be attached to services. **Networks:** Defines virtual networks for container communication, allowing services to resolve each other by name for easy internal communication

Difficulty: 5/10

services, networks, volumes

A Compose file defines three main sections:

1
Services: Specifies the containers to run and their runtime configuration (image, build context, ports, environment variables, volumes, depends_on, healthcheck, etc.).
2
Volumes: Declares named persistent storage volumes that can be attached to services.
3
Networks: Defines virtual networks for container communication, allowing services to resolve each other by name for easy internal communication

Scenario Questions

0-2 years experience

1You need to spin up a simple web app with a database using docker-compose. Which top‑level sections would you include in the yaml and what purpose does each serve?
2If you add a new service to an existing docker-compose.yml, which top‑level key must you modify and what does that key define?
3What happens if you reference a volume in a service but omit the top‑level 'volumes' section?

Follow-up Questions

Can you show how a service references a custom network you defined?
What happens if you mount a named volume in multiple services?
How does Docker Compose behave when one of these top‑level sections is omitted?