How to create and manage containers with Docker CLI - without creating a Dockerfile

Create a Linux container

You can run the commands in this guide without a copy of this docker-quickstarts repo and without creating a Dockerfile.

Choose a base image

All containers need a base image. First figure out what OS you want and then find an appropriate image.

Here are some flavors of Linux:

  • ubuntu
  • alpine (Debian)
  • archlinux
  • centos

If you want to specify a version, you can do something like this:

  • ubuntu:latest (same as just using ubuntu)
  • ubuntu:20.04
  • ubuntu:focus

The Docker hub site is a good place to look for more options. You don’t have to download from the site, as you just need a valid name to reference on the command-line. If you want, you can choose something more specialized like a Node.js, Python or Go container (which internally probably uses Ubuntu.

Note that you can run Linux containers on a Linux, Windows or macOS system. However, you can only run a Windows container on a Windows machine, based on this thread.

Download image

We use centos for the examples below, but you can use any image name you want.

$ docker pull centos

You can then reuse this image in other images or in a container.

Run container

Basic

Start running an unammed container using centos image. If you skipped the pull command above, Docker will download the image for you.

$ docker run centos

You’ll see output logged. If you prefer to run in the background:

$ docker run -d centos

  -d, --detach   Run container in background and print container ID

Clean up

$ docker run --rm -d centos

Use this flag to remove the container when it is finished.

      --rm      Automatically remove the container when it exits

Name

Start a container using a custom name.

$ docker run --name my-container centos

This allows you to have multiple containers for the same image.

$ docker run --name my-container-1 centos
$ docker run --name my-container-2 centos

If you don’t add the name, you’ll get a random name that Docker decides for you. Which is fine if you use --rm and don’t need the container to persist.

Optionally run in background mode with -d and using -t for SSH access (I think).

Run interactive

Run interactive shell.

$ docker run -it centos

This might just run and exit immediately. So specify a command to execute. Such as bash to start as Bash Shell console in the container.

$ docker run -it centos bash
root@56874667f6fc:/root#

Flags used:

  -i, --interactive                    Keep STDIN open even if not attached
  -t, --tty                            Allocate a pseudo-TTY

Check running containers

$ docker ps

Example output:

CONTAINER ID   IMAGE       COMMAND       CREATED        STATUS        PORTS   NAMES
8332318ac5b5   centos      "/bin/bash"   8 seconds ago  Up 6 seconds          my-container
...

Start terminal

Start a Bash terminal in an already running container. Use bash or sh.

docker exec -it my-container bash

Now you’re in the container.

[root@abcde1234 /]#

Look around.

[root@abcde1234 /]# ls
bin dev etc ...

Exit using exit for CTRL+D

[root@abcde1234 /]#

Stop

$ docker stop my-container

Start

Start the container up again. You’ll keep any data and packages you have before.

$ docker start my-container

Remove

Delete a container. You must stop it first.

$ docker rm my-container

Or use this to remove the container when it exits.

$ docker run -rm OPTIONS

Use Network Chuck’s image

Download image which has been tagged “frenchpress”. This could be a version number too.

$ docker pull thenetworkchuck/nccoffee:frenchpress

$ docker run -t -d -p 80:80 --name nccoffee thenetworkchuck:frenchpress

Check usage of containers

$ docker stats