Docker Commands

Quick reference of essential Docker commands.

1. List Images and Containers

Display the images available on your machine.

docker images

See containers currently running.

docker ps

Include stopped containers with -a.

docker ps -a

Start or stop existing containers.

docker start <CONTAINER_ID>

docker stop <CONTAINER_ID>

Inspect a container's logs.

docker logs <CONTAINER_ID>

Remove stopped containers.

docker rm <CONTAINER_ID>

docker rm hello-world

Remove an image you no longer need.

docker rmi <IMAGE_ID>

docker rmi hello-world:latest

Docker Hub hosts ready-to-use images.

Download the Postgres 12.0 image.

docker pull postgres:12.0

Launch a container from that image.

docker run \
  --name postgres120 \
  -e POSTGRES_PASSWORD=postgres \
  -d \
  -p 5432:5432 \
  postgres:12.0

Open a shell inside the running container.

docker exec \
  -it postgres120 \
  /bin/bash

root@bad052b5ddae:/#

Options:

Option	Description
`--name`	Assigns the container name.
`-e`	Defines environment variables.
`-d`	Runs the container in detached mode.
`-p`	Publishes container ports (`host:container`).
`-it`	Opens an interactive shell inside the container.

A Dockerfile lists the instructions needed to build a custom image.

app
  ├─ Dockerfile
  └─ index.py

index.py

#!/usr/bin/env python3
print("Docker es mágico!")

Dockerfile

FROM python:3
WORKDIR /usr/src/app
COPY . .
CMD [ "python", "./index.py" ]

Inside the app directory, build the image.

docker build \
  -t python-example \
  .

Note: the -t option assigns the image name and optional tag (name:tag).

Run a container based on the newly built image.

docker run \
  --name magic \
  python-example

Docker es mágico!

Published: May 23, 2020