Batch 4: Cloud Ansible AWS & Azure Docker & Podman Apache & NGINX ← Full TOC

🐳 Docker Basics — docker run, build, push, pull, ps, images, volumes

Docker packages applications with all dependencies into portable containers. Every container runs from an image. Images are built from Dockerfiles and stored in registries. Podman is a daemonless Docker-compatible alternative.

📋 Reference

Item	Syntax	Description
docker run	docker run [OPTIONS] IMAGE [COMMAND]	Run a container from an image
-d	docker run -d nginx	Detached mode — run in background
-p	docker run -p 8080:80 nginx	Port mapping host:container
-v	docker run -v /host/path:/container/path	Bind mount volume
-e	docker run -e ENV_VAR=value	Set environment variable
--name	docker run --name myapp nginx	Assign container name
--rm	docker run --rm ubuntu echo hello	Auto-remove when container exits
-it	docker run -it ubuntu bash	Interactive terminal
--network	docker run --network mynet myapp	Connect to network
docker ps	docker ps / docker ps -a	List running / all containers
docker images	docker images	List local images
docker pull	docker pull ubuntu:22.04	Pull image from registry
docker push	docker push myregistry/myimage:tag	Push image to registry
docker build	docker build -t myimage:tag .	Build image from Dockerfile in current dir
docker exec	docker exec -it mycontainer bash	Execute command in running container
docker logs	docker logs -f mycontainer	Stream container logs
docker stop	docker stop mycontainer	Gracefully stop container (SIGTERM)
docker kill	docker kill mycontainer	Force stop container (SIGKILL)
docker rm	docker rm mycontainer	Remove stopped container
docker rmi	docker rmi myimage:tag	Remove image
docker volume	docker volume create / ls / rm / inspect	Manage named volumes
docker network	docker network create / ls / rm	Manage networks
docker inspect	docker inspect mycontainer	Detailed JSON info about container
docker stats	docker stats	Live resource usage for containers
docker cp	docker cp mycontainer:/path/file ./local	Copy files between container and host
docker commit	docker commit mycontainer myimage:new	Create image from container (prefer Dockerfile)
docker tag	docker tag myimage:latest myimage:v1.0	Tag image with new name
docker login	docker login registry.example.com	Authenticate to registry
docker system prune	docker system prune -af	Remove all unused containers, images, networks
podman	podman run/build/push/pull/ps	Podman: drop-in Docker replacement, daemonless, rootless

💡 Example

# Docker essential commands

# ── Pull and run ──────────────────────────────────────────────
docker pull ubuntu:22.04
docker run --rm ubuntu:22.04 echo "Hello from container"
docker run -it ubuntu:22.04 bash   # interactive shell

# Run web server
docker run -d --name nginx-test -p 8080:80 nginx:alpine
curl http://localhost:8080          # test it
docker logs nginx-test              # check logs
docker stop nginx-test && docker rm nginx-test

# ── Build image ───────────────────────────────────────────────
mkdir myapp && cd myapp
cat > Dockerfile << 'EOF'
FROM python:3.12-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
EXPOSE 8080
USER nobody
CMD ["python", "app.py"]
EOF

docker build -t mywebuniversity/api:1.0 .
docker build -t mywebuniversity/api:1.0 --no-cache .  # force rebuild
docker build --build-arg ENV=production -t myapp .

# ── Run your image ─────────────────────────────────────────────
docker run -d \
  --name mywebuniversity-api \
  -p 8080:8080 \
  -e DATABASE_URL=postgresql://db:5432/mydb \
  -e LOG_LEVEL=info \
  --restart unless-stopped \
  mywebuniversity/api:1.0

docker exec -it mywebuniversity-api bash  # debug inside
docker logs -f mywebuniversity-api         # stream logs
docker stats mywebuniversity-api           # resource usage

# ── Volumes ────────────────────────────────────────────────────
docker volume create myapp-data
docker run -v myapp-data:/app/data myapp       # named volume
docker run -v $(pwd)/data:/app/data myapp      # bind mount
docker volume inspect myapp-data
docker volume rm myapp-data

# ── Registry ──────────────────────────────────────────────────
docker tag mywebuniversity/api:1.0 ghcr.io/myorg/api:1.0
docker login ghcr.io -u myuser --password-stdin <<< "$GITHUB_TOKEN"
docker push ghcr.io/myorg/api:1.0
docker pull ghcr.io/myorg/api:1.0

# ── Podman (drop-in replacement) ──────────────────────────────
# All docker commands work with podman:
podman run -d --name nginx -p 8080:80 nginx
podman ps; podman logs nginx; podman stop nginx
# Rootless containers — no daemon required
podman run --rm alpine echo "rootless container!"
# Generate systemd unit for auto-start
podman generate systemd --name nginx --files --new

🏠 Index | Dockerfile Best Practices →