100 Days of DevOps: Day 38

Testing Containerized Application Features

To begin testing new containerized application features for the Nautilus project, the DevOps team was tasked with preparing a specific Docker image on App Server 3. The plan was to use a busybox:musl image and re-tag it for the new project.

Step 1: Pull the Busybox Image

The first action was to download the busybox:musl image from Docker Hub using the docker pull command. This ensures the required image is available on the local server.

[banner@stapp03 ~]$ docker pull busybox:musl
musl: Pulling from library/busybox
8e7bef4a92af: Pull complete 
Digest: sha256:254e6134b1bf813b34e920bc4235864a54079057d51ae6db9a4f2328f261c2ad
Status: Downloaded newer image for busybox:musl
docker.io/library/busybox:musl

Once the download was complete, the docker images command was used to verify that the image was successfully added to the server's local repository.

[banner@stapp03 ~]$ docker images
REPOSITORY    TAG        IMAGE ID        CREATED          SIZE
busybox       musl       44f1048931f5    11 months ago    1.46MB

Step 2: Re-tag the Image

The next step was to create a new tag for the image, specifically busybox:media. The docker tag command is used for this purpose. This command creates a new tag that points to the same underlying image, identified by its IMAGE ID.

[banner@stapp03 ~]$ docker tag busybox:musl busybox:media

To confirm that the re-tagging was successful, the docker images command was run again. The output now shows two tags for the same IMAGE ID, indicating the task is complete.

[banner@stapp03 ~]$ docker images
REPOSITORY    TAG        IMAGE ID        CREATED          SIZE
busybox       media      44f1048931f5    11 months ago    1.46MB
busybox       musl       44f1048931f5    11 months ago    1.46MB