docker-compose cheat sheet

docker-compose cheat sheet

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Why the user and data persisted despite docker compose down -v

Even though you used docker compose down -v (which does delete named or anonymous volumes created by Docker Compose), your docker-compose.yml includes this line

volumes:
  - "./librenms:/data"

The ./librenms folder on your host stores LibreNMS data.

When you did docker compose down -v, Docker:

    Removed volumes it manages (like the db volume, if it's named).

    Did not touch bind-mounted folders like ./librenms.

So when you brought the containers up again with docker compose up -d --build, the container saw:

    "Oh, the /data directory already has previous config, users, etc."
    
    
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docker compose exec librenms mysql -h db -u librenms -p

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$ docker compose up -d --build

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docker compose up -d --build
write /var/lib/docker/tmp/GetImageBlob1490303091: no space left on device

df -h
/dev/sda8        71G   11G   57G  16% /home
/dev/sda5       6.4G  6.3G     0 100% /var

explain how to fix this, there is much space on /home

Docker stores all its images, containers, volumes, and temporary files under /var/lib/docker by default. Since /var is a small (6.4 GB) and full partition, Docker cannot proceed — even though /home has plenty of space

Solution: Move Docker storage to /home

We will move Docker's storage location from /var/lib/docker to /home/docker-data (or another directory with more space).

tep-by-step Instructions
1. Stop Docker

sudo systemctl stop docker

2. Create a new directory on /home

sudo mkdir -p /home/docker-data

3. Move existing Docker data (if any)

sudo rsync -aP /var/lib/docker/ /home/docker-data/

4. Configure Docker to use the new location

Create or edit Docker’s daemon config:

sudo mkdir -p /etc/docker
sudo nano /etc/docker/daemon.json

Add:

{
  "data-root": "/home/docker-data"
}

5. Restart Docker

sudo systemctl start docker

6. Verify

Run:

docker info | grep "Docker Root Dir"

You should see:

Docker Root Dir: /home/docker-data

💡 Optional: Clean up old data

Once you're sure everything works, you can delete the old directory:

sudo rm -rf /var/lib/docker

#=====================================================================
docker compose -f docker-compose.json up #use JSON instead of YAML compose file
#=====================================================================
docker compose -f ~/hello_world/docker-compose.yml build
docker compose -f ~/hello_world/docker-compose.yml up -d
docker compose ps # Lists containers.
docker compose stop
docker compose start # Starts existing containers for a service.
docker compose stop # Stops running containers without removing them.
docker compose pause # Pauses running containers of a service.
docker compose unpause # Unpauses paused containers of a service
docker compose up #Builds, (re)creates, starts, and attaches to containers for a service
docker compose up -d #Create docker image and run container in the background
docker compose down # Stops containers and removes containers, networks, volumes, and images created by up.
docker compose down -v # tear down the containers and volumes
docker compose --version
docker compose ps
docker compose images #List images used by the created containers
docker compose stop
docker compose run web
docker compose down
	
docker compose -f docker-compose-dev.yml up -d app1
docker compose -f docker-compose-test-local.yml run --rm unit
docker compose -f docker-compose-test-local.yml build app -> as an alternative, define build arguments inside a Docker Compose file
docker compose build

docker compose config

docker compose -f docker-compose-test-local.yml up -d staging-dep
docker compose -f docker-compose-test-local.yml ps
docker compose -f docker-compose-test-local.yml run --rm staging
docker compose -f docker-compose-test-local.yml down
docker compose -f docker-compose-local.yml up -d registry
#=====================================================================
docker compose logs
docker compose logs -f initializer #track progress
docker compose logs initializer | grep "Admin password:" #obtain admin credentials

stream logs in real-time, use the -f (follow) flag:
docker compose -f librenms/docker-master/examples/compose/compose.yml logs -f

limit the number of lines displayed using the --tail option
docker compose -f librenms/docker-master/examples/compose/compose.yml logs --tail=100

docker compose -f librenms/docker-master/examples/compose/compose.yml logs --timestamps

for a specific service
docker compose -f librenms/docker-master/examples/compose/compose.yml logs --timestamps web

View logs for all services
docker-compose logs

View logs for Nginx (web)
docker-compose logs web

save logs for analysis, redirect output
docker-compose logs web > web_logs.txt

Checking Logs of a Specific Container
docker ps
docker logs -f <container_id>

#=====================================================================
docker compose up -d #Create docker image and run container in the background
docker compose exec kali /bin/bash #Create docker image and run container in the background
#=====================================================================
docker build -t kalicmd . --file=/vagrant/dockerfiles/kalilinux/toolkali
docker compose --file /vagrant/dockerfiles/kalilinux/docker-compose.yml run kali-service
docker compose --file /vagrant/dockerfiles/kalilinux/docker-compose.yml ps #Lists containers

cat docker-compose.yml
version: '3'
services:
  kali-service:
    image: "kalicmd"
    volumes:
      - /mnt/share-kali:/share
      - /mnt/share-kali/.bash_history:/root/.bash_history
#=====================================================================
docker compose build --no-cache #Force the execution of each step/instruction in the Dockerfile
docker compose build --no-cache && docker compose up -d --force-recreate #t recreate all containers
docker build --pull --no-cache --tag myimage:version #force rebuilding of layers already available
#=====================================================================
#=====================================================================
WINDOWS
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docker compose version
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#environment variable, non-default dockere file name
#docker-compose.yaml
version: '3.8'
services:
  myservice:
    build:
      context: .
      dockerfile: ./docker/Dockerfile.myservice
    image: myself/myservice
    env_file:
     - ./var.env
    environment:
     - VAR_C=C
     - VAR_D=D
    volumes:
     - $HOME/myfolder:/myfolder
    ports:
     - "5000:5000"

#=====================================================================
cat Dockerfile.test
cat docker-compose.test.yml
docker compose -f ~/hello_world/docker-compose.test.yml -p ci build
docker compose -f ~/hello_world/docker-compose.test.yml -p ci up -d
docker compose -p ci stop
#=====================================================================
                  Docker Compose v2	          Docker compose v3
 Multi-host	      No	                        Yes                  
 Start services	  docker compose up -d	      docker stack deploy --compose-file=docker-compose.yml  
 Scale service	  docker compose scale =	    docker service scale =
 Shutdown	        docker compose down	        docker stack rm

#=====================================================================
# docker-compose.yml
version: '3'

services:
  web:
    build: .
    # build from Dockerfile
    context: ./Path
    dockerfile: Dockerfile
    ports:
     - "5000:5000"
    volumes:
     - .:/code
  redis:
    image: redis
#=====================================================================
# Builds, (re)creates, starts, and attaches to containers for a service.
docker compose up
# Stops containers and removes containers, networks, volumes, and images created by up.
docker compose down
#=====================================================================
web:
  # build from Dockerfile
  build: .
#=====================================================================
  # build from custom Dockerfile
  build:
    context: ./dir
    dockerfile: Dockerfile.dev
#=====================================================================
  # build from image
  image: ubuntu
#=====================================================================
ports:
    - "3000"
    - "8000:80"  # guest:host
#=====================================================================
  # expose ports to linked services (not to host)
  expose: ["3000"]
#=====================================================================
# command to execute
  command: bundle exec thin -p 3000
  command: [bundle, exec, thin, -p, 3000]
#=====================================================================
  # override the entrypoint
  entrypoint: /app/start.sh
  entrypoint: [php, -d, vendor/bin/phpunit]
#=====================================================================
  volumes:
    - /var/lib/mysql
    - ./_data:/var/lib/mysql

version: '2'
  services:
    cms:
       image: <IMAGE>:<TAG>
       ports:
       - <LOCAL_PORT>:<CONTAINER_PORT>
       volumes:
       - <LOCAL_PATH>:<CONTAINER_PATH>
       
#=====================================================================
# join a pre-existing network
networks:
  default:
    external:
      name: frontend
#=====================================================================
# creates a custom network called `frontend`
networks:
  frontend:
#=====================================================================
  # makes the `db` service available as the hostname `database`
  # (implies depends_on)
  links:
    - db:database
    - redis
#=====================================================================
  # make sure `db` is alive before starting
  depends_on:
    - db
#=====================================================================
services:
  web:
    dns: 8.8.8.8
    dns:
      - 8.8.8.8
      - 8.8.4.4
#=====================================================================
a Bash script to automate the creation of a superuser for NetBox using Docker Compose. It uses the provided username, email, and password, and bypasses the password validation prompt.

#!/bin/bash

# Variables
USERNAME="admin"
EMAIL="[email protected]"
PASSWORD="Netbox2025!"

# Run the createsuperuser command non-interactively
sudo docker compose -f netbox-docker/docker-compose.yml exec netbox /opt/netbox/netbox/manage.py createsuperuser \
    --username "$USERNAME" \
    --email "$EMAIL" \
    --no-input || true

# Set password using Django shell
sudo docker compose -f netbox-docker/docker-compose.yml exec netbox /opt/netbox/netbox/manage.py shell -c "
from django.contrib.auth import get_user_model;
User = get_user_model();
user = User.objects.get(username='$USERNAME');
user.set_password('$PASSWORD');
user.save();
print('✅ Superuser created successfully with provided password.')
"

echo "🎉 NetBox superuser created with username '$USERNAME' and email '$EMAIL'"

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