Running Containers

First PublishedFeb 19, 2026ByAtif Alam

You run an image as a container with docker run. Common flags control detached vs interactive mode, port mapping, volumes, and environment variables.

Basic Run

# Run once; use default CMD
docker run nginx:alpine

# Run in background (detached)
docker run -d nginx:alpine

# Run interactively with a TTY (e.g. shell)
docker run -it alpine:3.19 sh

Common Flags

Flag	Short	Purpose
—detach	-d	Run in background.
—interactive	-i	Keep stdin open.
—tty	-t	Allocate a pseudo-TTY. Use -it for an interactive shell.
—publish	-p	Map host port to container port (e.g. -p 8080:80).
—volume	-v	Mount a volume or bind mount (e.g. -v /data:/app/data).
—env	-e	Set environment variable (e.g. -e NODE_ENV=production).
—name		Give the container a name for easier reference.
—rm		Remove the container when it exits.

Examples

# Run nginx, publish host 8080 → container 80, remove on exit
docker run -d --rm --name web -p 8080:80 nginx:alpine

# Run with env var and bind mount
docker run -d -e DB_HOST=db -v $(pwd)/config:/app/config myapp:1.0

# Interactive shell in a running image
docker run -it --rm alpine:3.19 sh

Lifecycle

docker start <container>   # Start a stopped container
docker stop <container>   # Stop (SIGTERM then SIGKILL)
docker restart <container>
docker rm <container>     # Remove (must be stopped unless -f)
docker ps                 # List running containers
docker ps -a              # List all containers

Logs and Exec

# Follow logs
docker logs -f <container>

# Run a command in a running container
docker exec -it <container> sh
docker exec <container> env

Key Takeaways

• Use -d for background, -it for interactive shell, -p for port mapping, -v for volumes, -e for env vars.
• docker start/stop/rm manage lifecycle; docker logs and docker exec inspect and run commands in running containers.