Build a Practical Multi-Container Applications Example in Docker and Containers

Define the build target

For Multi-Container Applications, build and run a small containerized service, connect it to a second service or volume, inspect logs, stop/restart it, and verify non-root/runtime settings where practical. Build the boundary case using this implementation lens: Use image layers, Dockerfiles, container process state, logs, mounts, networks, Compose services, security metadata, and runtime diagnostics.

Keep the Multi-Container Applications build centered on these technical constraints: Image versus container. Process/exit/log lifecycle. Apply them through this path lens: Use image layers, Dockerfiles, container process state, logs, mounts, networks, Compose services, security metadata, and runtime diagnostics. Use image layers, Dockerfiles, container process state, logs, mounts, networks, Compose services, security metadata, and runtime diagnostics.

Implement the core behavior

Implement Multi-Container Applications around the module artifact—a working multi-container applications exercise with a documented technical result—and keep the implementation specific to this path context: Use image layers, Dockerfiles, container process state, logs, mounts, networks, Compose services, security metadata, and runtime diagnostics.

services:
  web:
    image: nginx:1.27
    ports: ["8080:80"]
    read_only: true
    tmpfs: [/var/cache/nginx, /var/run]
  client:
    image: curlimages/curl:8.12.1
    command: ["sh", "-c", "sleep 3; curl -f http://web/"]
    depends_on: [web]

docker compose up --abort-on-container-exit

The client reaches the web service by service name on the Compose network; localhost is not used for cross-container traffic.

practice/\n├── README.md\n├── multi-container-applications-build.yaml\n└── evidence/\n    └── expected-result.txt

Run the complete path

Run one realistic Multi-Container Applications case end to end and record the required evidence: the module-specific command, output, test, rendered state, query result, log, or measurement that proves the exercise worked. Interpret the result through this path context: Use image layers, Dockerfiles, container process state, logs, mounts, networks, Compose services, security metadata, and runtime diagnostics.

Change one meaningful condition

Modify one condition central to Multi-Container Applications using this path context: Use image layers, Dockerfiles, container process state, logs, mounts, networks, Compose services, security metadata, and runtime diagnostics. Predict the new result before rerunning the same workflow.

Verify the artifact

Your deliverable is a working multi-container applications exercise with a documented technical result.

Common mistakes to avoid

• Main process exits immediately.
• Localhost used for another container.
• Data stored only in ephemeral layer.
• Secret baked into image or root used unnecessarily.