DevOps Classroom notes 21/Sep/2026

tempfs mount volume:

• Data is store in hosts memory
• never store data in hard disk
• store information when running container untill stop

–tmpfs /app/tmp:

Example: httpd server need access file faster

docker run -dit  --name apache2 --tmpfs /usr/local/apache2/htdocs/:rw,size=64m httpd:latest

Docker compose

• Docker compose define and run multiple container from a single yaml file
• compose.yaml or docker-compose.yaml

Basic structure

services:
    web:
      image/build:
      port:
      volume:
      network:
    frontend:
      image/build:
      port:
      volume:
      network:
    backend:
      image/build:
      port:
      volume:
      network:

volumes: # named volumes
  demo:
  app:
  api:

networks:
  host:
  - app-net

sample docker compose file

services:
  apache2:
    image: httpd:latest
    container_name: apache2_container
    ports:
      - "80:80"
    volumes:
      - ./html:/usr/local/apache2/htdocs/
    networks:
      - webnet
    depends_on: ["mysql"]
  mysql: 
    image: mysql:latest
    container_name: mysql
    ports:
      - "3306:3306"

networks:
  webnet:
    driver: bridge

volumes:
  html:
    driver: local

Docker compose comands

1. docker compose up -d # run docker services , create network and volume
2. docker compose ps # list services runing
3. docker compose logs -f apache2
4. docker compose exec apache2 sh`` or /bin/bash“`
5. docker compose down
6. verbose -vvv docker compose down -v
7. docker compose config # validate or view the final configuration
8. -f file path docker compose up -d -f ./app-compose.yaml

common Service keys

• image: prebuild image or existing image (image: http:latest)
• build: build the image from dockerfile (build: ./Dockerfile)
• port: Publish Port [host:containerport] (“8080:80”)
• enviroment: set env varaible ( – KEY=Value)

enviroment:
  - name: demo
  - app: 1.2
  - team: devops 

• env_file: local env file (env_file: .env)
• volume: mount volume path to container - ./html:/usr/local/apache2/htdocs/
• depends_on: starting order or wait for other service (depends_on: [“web”])
• network: Attach network to container

networks:
 - webnet

• restart: Restart policy automatically start container if any failures ( restart: unless-stopped )
• command: override default command (command: [“java”, “-jar”, “*.jar”])
• Health-check: container health test (healthcheck: cmd)

Task:

1. try convert nop app and database as docker compose yaml file.