Basic Docker Commands

Containers

Start a container

• docker run nginx
  • if image is not present pull image from docker hub
  • if image is present it will reuse
• docker run -it nginx bash
  • to see directly in terminal use -it option

Give name to a container

• docker run --name <name> <image>

List containers

→ docker randomly give conatiner_id and names to running container

• docker ps
  • list containers
  • running containers
• docker ps -a
  • running containers + previously stopped or exited containers

Stop a container

• docker stop <container id>
• docker stop <docker name>
  • no running containers
  • remains in docker ps -a with Exited status

Remove containers

→ when want to get rid of it from lying space

• docker rm <container id>
• docker rm <docker name>
  • no longer present in docker ps -a

Get container ids

• docker ps -aq
• remove all containers
  • docker rm $(docker ps -aq)

Images

List images

• docker images

Get all image ids

• docker images -aq

Remove images

• docker rmi nginx
  • delete all dependent containers to remove image!

Download an image

• docker pull nginx
  • only pull image, not run docker image

Docker run

No hosting in docker

Containers are not meant to host an operating system.
Containers are meant to run a specific task or process.

• such as to host an instance of a web server or application server, …

Once the task is complete the container exits a container.
Container only lives as long as the process inside it is alive.

Append a command

• docker run ubuntu sleep 5

Execute a command

I would like to see the contents of a file inside some particular containers.

• docker exec <run name> cat /etc/hosts

Attach and Detach

• docker run kodekloud/simple-webapp
  • when attached, you can not do anything.
• docker run -d kodekloud/simple-webapp
  • detach mode, it runs in background mode.
  • To attach again
    • docker attach <name or run_id>

Docker Run

Tag

• docker run <image>:<tag>
  • no specific tag → use latest tag.

STDIN

by default, docker container does not listen to standard input, even attached.

• -i
  • interactive mode
• -t
  • pseudo terminal
• -it
  • use two options

PORT Mapping

• IP of docker container
  • internal IP and is only accessible within the docker host.
• IP of docker host
  • -p
  • docker run -p <host_port>:<internal_port> <image name>

Volume Mapping

• docker container has its own isolated file system.
• if want to persist data, map a directory outside the container on the docker host to ad directory inside the container
• -v
• docker run -v <host volume>:<docker volume <image name>

Inspect Container

• docker inspect <container id | name>

Container Logs

• docker logs <container id | name>