Docker commands

Common Docker CLI and Compose examples for creating, monitoring, pruning and troubleshooting containers.

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Docker group membership is highly privileged

Adding a user to the docker group normally grants broad control over the Docker daemon and host. Limit membership to trusted administrators.

Add a user to the docker group

>_Add an existing user

usermod -a -G docker ec2-user

Create and start a container from the CLI

docker create \
  --name=webserver --net=host -e VERSION=latest \
  -e PUID=$(id -u docker) -e PGID=$(id -g docker) \
  -v /var/www/html:/app:ro \
  --restart unless-stopped nginx

docker start webserver

Equivalent Compose example

version: '2'
services:
  myproject:
    container_name: webserver
    build: ./
    volumes:
      - /var/www/html:/app
    restart: always
    network_mode: host

Start the Compose project:

>_Start the project

docker-compose up -d

Monitor containers

>_Container resource usage

docker stats

>_Processes inside a container

docker top container1

Remove unused Docker data

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Prune removes unused Docker data

docker system prune -a removes unused images as well as other unused Docker objects. Review what is required before running it on a shared host.

>_Prune unused data

docker system prune -a

Troubleshoot inside a container

>_Open a shell

docker exec -it webserver /bin/bash