Hello Reader,

A container icebreaker interview question is the fundamental container workflow from the local machine to the cloud. In this edition, we will start with the manual process that every project starts with, then we will show how this manual process gives way to CICD and then how it evolves to a more mature pipeline.

Let's start with understanding the foundational flow first:

1. Developer writes code, and associated Dockerfile to containerize the code in her local machine
2. She uses “Docker build” command to create the container image, in her local machine. At this point container image is saved in the local machine
3. Developer uses “Docker run” command to run the container image, and test out the code running from the container. Developer can repeat Steps 1-3, till the testing goes as per the requirements
4. Next, developer runs “Docker push” command to push the container image from the local machine to a container registry. Some examples are DockerHub, or Amazon ECR.
5. Finally, using “Kubectl apply” command, an YAML manifest which has the URL of the container image from the Amazon ECR, is deployed into the running Kubernetes cluster.

This is the manual flow, and most of these steps in real-world projects are automated. Let's take a look at that next on how these manual steps are translated into CICD:

1. After developer tests the container in local, she checks in Code, Dockerfile, and manifest YAMLs to an application repository. CI tools (e.g., Jenkins) kick off, build the container image and save the image in a container registry such as Amazon ECR.
2. CD tools (e.g. Jenkins) update the deployment manifest files with the tag of the container image.
3. CD tools (e.g. Jenkins) execute the command to deploy the manifest files into the cluster, which, in terms, deploys the newly built container in the Amazon EKS cluster.

The above is the foundational CICD. The testing, and security checks are eventually included in the CICD pipeline itself. As a final iteration, let's take a look at that:

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However, like anything in Kubernetes, it's always evolving. Currently, the trend is to do the CD part with GitOps. And we are seeing many feature releases in that area. But that's for another edition!
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Raj Speaking in AWS Re:Invent 🎤

Next week, I will be at Las Vegas, USA, Dec 2-6. I will speak there at three sessions including one major breakout session. I will also be at AWS Kubernetes Kiosk on the Expo Floor Wednesday from 1:00 pm - 4:00 pm local time if you want to come and say hi 👋! I will post some pics from the event in the next edition's newsletter.

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Keep learning and keep rocking 🚀,

Raj