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Challenge - Beginner project

Set up a project that combines all beginner concepts.

Challenge: the beginner project

All the pieces of the beginner section: an API built with your own Dockerfile, a Redis cache, a shared network, environment variables and a health check. The Compose file defines both the build and the run:

services:
  api:
    build: .
    image: api:1.0.0
    ports:
      - "3000:3000"
    env_file: api.env
    environment:
      REDIS_URL: redis://cache:6379
    depends_on:
      cache:
        condition: service_healthy
    restart: unless-stopped
  cache:
    image: redis:7
    healthcheck:
      test: ["CMD", "redis-cli", "ping"]
      interval: 5s

Practice The project's compose file

Write a compose.yaml: the api service with build: ., image: api:1.0.0, "3000:3000", env_file: api.env, and condition: service_healthy for cache under depends_on; the cache service with redis:7 and test: ["CMD", "redis-cli", "ping"] under healthcheck.

Starter code

terminal
# compose.yaml
# buraya yaz

Sample solution

terminal
# compose.yaml
services:
  api:
    build: .
    image: api:1.0.0
    ports:
      - "3000:3000"
    env_file: api.env
    depends_on:
      cache:
        condition: service_healthy
  cache:
    image: redis:7
    healthcheck:
      test: ["CMD", "redis-cli", "ping"]

Expected output

[+] Running 3/3
 ✔ Image api:1.0.0  Built
 ✔ Container proje-cache-1  Healthy
 ✔ Container proje-api-1  Started

Practice Update the code

You changed the code. Write two commands: rebuild only the api service and update it in the background; then show the variables by running the env command in the api container.

Starter code

terminal
# buraya yaz

Sample solution

terminal
docker compose up -d --build api
docker compose exec api env

Expected output

[+] Running 2/2
 ✔ Image api:1.0.0  Built
 ✔ Container proje-api-1  Started
NODE_ENV=production
REDIS_URL=redis://cache:6379
LOG_LEVEL=info

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 When does the cache service's healthcheck succeed?

  • Always after 5 seconds
  • When api starts
  • When redis-cli ping returns with a zero exit code (PONG) Correct answer
  • As soon as the container starts

Explanation: The health check looks at the test command's exit code.

2 Load the environment variables from a file.

Question 
  api:
    build: .
    ____: api.env
Answer 
  api:
    build: .
    env_file: api.env

Explanation: In Compose it is written with an underscore: env_file.

3 Match.

Term Meaning
build: . Your own Dockerfile
image: api:1.0.0 Build tag
env_file Settings from file
service_healthy Start when ready

All lessons in Beginner

1 What is Docker?

  1. What is Docker?
  2. Containers and virtual machines
  3. Images and containers
  4. Docker architecture
  5. Use cases
  6. Summary - What is Docker

2 Installation and first commands

  1. Installing Docker
  2. docker version
  3. docker info
  4. The hello-world container
  5. Docker Desktop
  6. Summary - Installation

3 First container

  1. docker run basics
  2. Running in the background
  3. docker ps
  4. docker stop and rm
  5. docker logs
  6. Summary - First container

4 Dockerfile basics

  1. What is a Dockerfile?
  2. The FROM instruction
  3. The RUN instruction
  4. COPY and ADD
  5. CMD and ENTRYPOINT
  6. Summary - Dockerfile

5 Build and images

  1. docker build
  2. Tagging images
  3. Build context
  4. Layers and cache
  5. .dockerignore
  6. Summary - Build

6 docker run options

  1. Interactive mode
  2. Naming containers
  3. Restart policy
  4. Working directory
  5. Switching users
  6. Summary - docker run

7 Image management

  1. docker images
  2. docker rmi
  3. docker pull
  4. docker push
  5. docker tag
  6. Summary - Image management

8 Port mapping

  1. The port concept
  2. The -p flag
  3. Multiple ports
  4. Random ports
  5. IP binding
  6. Summary - Port mapping

9 Volumes and data

  1. Data persistence
  2. Named volumes
  3. The -v flag
  4. Bind mounts
  5. Volume management
  6. Summary - Volumes

10 Environment variables

  1. The -e flag
  2. The ENV instruction
  3. The ARG instruction
  4. env-file
  5. The WORKDIR instruction
  6. Summary - Environment

11 Project: docker-compose

  1. Compose design
  2. Service definition
  3. Database service
  4. Volume and network
  5. Putting it together - compose

12 Docker Hub and registry

  1. What is Docker Hub?
  2. docker login
  3. Searching images
  4. Official images
  5. Private registry
  6. Summary - Registry

13 Network basics

  1. Network drivers
  2. docker network ls
  3. Bridge network
  4. Container connectivity
  5. Publishing ports
  6. Summary - Network

14 Beginner final

  1. Challenge - Dockerfile
  2. Challenge - Build and run
  3. Challenge - Volume
  4. Challenge - Compose
  5. Challenge - Beginner project