Docker busybox: Hello World Application

Step 1: Open the terminal or command prompt and execute the below command.

docker run busybox echo Welcome to Docker programming

$docker run busybox echo Welcome to Docker programming
Unable to find image 'busybox:latest' locally
latest: Pulling from library/busybox
8e674ad76dce: Pull complete 
Digest: sha256:7a4d4ed96e15d6a3fe8bfedb88e95b153b93e230a96906910d57fc4a13210160
Status: Downloaded newer image for busybox:latest
Welcome to Docker programming

docker run busybox echo Welcome to Docker programming

We passed 'busybox' image to the docker run command. If the docker has this image in the local registry, it starts a new container instance with this image, else it downloads the image from the public registry.

Once the image is downloaded by docker, it starts the container with 'busybox' image and executes the command "echo Welcome to Docker programming".

Step 2: Execute the command ‘docker ps -a’ to list all the containers in your local system.

$docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                     PORTS               NAMES
d44ecdb5c842        busybox             "echo Welcome to Doc…"   3 minutes ago       Exited (0) 3 minutes ago                       wonderful_mendeleev

From the output of 'docker ps -a' command, you can see the container id, image name, command that is executed, name of the image, etc.,

Step 3: Execute the command 'docker run busybox echo Welcome to Docker programming' again.

$docker run busybox echo Welcome to Docker programming
Welcome to Docker programming

Since the image 'busybox' is already presented on the docker local registry, it do not download the image again.

Execute the command 'docker ps -a'.

$docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS                          PORTS               NAMES
35fb6627ce1b        busybox             "echo Welcome to Doc…"   About a minute ago   Exited (0) About a minute ago                       flamboyant_einstein
d44ecdb5c842        busybox             "echo Welcome to Doc…"   7 minutes ago        Exited (0) 7 minutes ago                            wonderful_mendeleev

Step 4: Execute the command 'docker images' to list all the images in local registry.

$docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
busybox             latest              e4db68de4ff2        4 days ago          1.22MB

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