# First time setup:
docker-compose build    # Builds your custom image from Dockerfile
docker-compose up -d    # Starts containers using your custom image

# If you change the Dockerfile later:
docker-compose build    # Rebuild the image
docker-compose up -d    # Recreate containers with new image

# Or do both at once:
docker-compose up -d --build

• copy files to docker container: docker cp foo.txt container_id:/foo.txt
• copy files from docker container: docker cp container_id:/foot.txt foo.txt
• prune unneeded files (save disk space): sudo docker system prune -a -f

• docker system df: show overall space usage by category
• docker inspect $(docker ps -q) | grep -A 10 Mounts: see what volume goes with what container
• docker inspect CONTAINER_NAME --format '{{range .Mounts}}{{.Name}} -> {{.Destination}}{{println}}{{end}}' : list what volume is associated with the container
• docker ps: list docker containers

• When removing a service use docker compose down -v instead of docker compose down.
  • The -v removes the associated volumes at the same time.
• When updating images, after pulling and restarting, run docker image prune to remove the dangling images
• docker ps -a: see all containers, even the ones that are stopped

• Watchtower is a container which auto updates Docker containers
• It will only update containers with updates that have the same tag
  • to always get the latest version use the tag latest
  • you can check which images have which tags with docker images
    • some images might have latest but not be base images so they won't be updated
• check the logs: docker logs watchtower
• if you want Watchtower to skip trying to update an image add to docker-compose.yml

 services:
  db:
    # label the image as each image gets its own label
    image: mariadb:latest # an example
    labels:
      - "com.centurylinklabs.watchtower.enable=false" # ADD THIS LINE

• run watchtower immediately: docker run --rm -v /var/run/docker.sock:/var/run/docker.sock containrrr/watchtower --run-once

• docker run: run container
  • use the -d flag for “detach” i.e. run in background
  • use the -p flag to forward the port i.e. -p 9000:80 maps port 80 in the container to 9000 on the host
  • user the --name flag to name the container (otherwise it's auto generated)
• docker stop <ID>
• docker logs <ID>
• docker start <ID>: restart a container
• docker build <DIR_WHERE_Dockerfile_IS_LOCATED>: build the image
  • -t: add name and tag. Ex: docker build -t node-app:1.0 .

• Docker Hub is the default registry and it is the biggest public registry
• you can store a private or public registry on Docker Hub
• Each application gets its on repo in the registry

• All dockerfiles start with a parent image or “base image”
• define the base image with FROM
• copy files into the container: COPY
  • example: COPY package.json /app/
• set the working directory: WORKDIR
  • example: WORKDIR /app
• next come the dependencies: RUN <dependencies here>
  • example: RUN npm install
• for the last command in the docker file i.e. start the process: CMD
  • example: CMD ["node", "server.js"]