docker run

Creates and starts a new container from an image — the everyday entry point for running anything in Docker.

#docker #containers

Command

Common flags

SHELL

1docker run <image>

2docker run -d <image> # detached, runs in the background

3docker run -it <image> sh # interactive shell inside the container

4docker run -p <host-port>:<container-port> <image>

5docker run -v <host-path>:<container-path> <image>

6docker run --rm <image> # auto-remove the container on exit

7docker run --name <name> <image>

Typical combination

Web app, backgrounded, port-mapped

SHELL

1docker run -d --name <name> -p 3000:3000 -e NODE_ENV=production <image>

Flags explained

The flags you will use 90% of the time. Everything after the image name is passed to the container as its command.

Flag reference

SHELL

1-d # run in background (detached)

2-it # interactive + TTY, for shells

3--name <name> # fixed name instead of a random one

4-p <host>:<container> # publish a port, e.g. -p 8080:80

5-e KEY=value # set an environment variable

6--env-file .env # load env vars from a file

7-v <vol>:/path # mount a named volume

8-v $(pwd):/app # bind-mount the current folder

9--network <net> # attach to a user-defined network

10--rm # delete the container when it exits

11--restart unless-stopped # auto-restart policy

12-w /app # working directory inside container

13--memory 512m --cpus 1 # resource limits

14--entrypoint sh # override the image ENTRYPOINT

Everyday examples

Examples

SHELL

1# Throwaway shell in a clean Ubuntu, removed on exit

2docker run --rm -it ubuntu bash

4# Postgres with a persistent volume

5docker run -d --name db -p 5432:5432 \

6 -e POSTGRES_PASSWORD=secret \

7 -v pgdata:/var/lib/postgresql/data postgres:16

9# Run a one-off command against your code

10docker run --rm -v $(pwd):/app -w /app node:20 npm test

12# Override the default command

13docker run --rm alpine echo "hello"

Gotchas

A container stops as soon as its main process (PID 1) exits: a detached container that "disappears" usually crashed, so check docker logs
-p is host:container. Getting the order wrong is the most common port mistake
Without --rm, every run leaves a stopped container behind (see docker ps -a)
Running without a tag pulls :latest, which is not pinned and can change under you
Named volumes survive docker rm; bind mounts point at host files directly

Never pass real secrets with -e on shared machines: they are visible in docker inspect and shell history. Prefer --env-file or secrets.