/rainbow

Primary LanguageGoOtherNOASSERTION

Kubernetes Rainbow Deploys

Overview

This repository demonstrates a technique for deploying Kubernetes services that require extended draining periods for established connections. It utilizes a "rainbow" approach, leveraging multiple deployments and service selectors to achieve graceful transitions without disrupting ongoing interactions.

Prerequisites

  • Kubernetes cluster (e.g., Minikube)
  • Docker
  • Make

Demo

The repository includes a simple Go application serving HTTP and TCP connections.

  1. Initialize:

    • Start Minikube.
    • Configure Docker environment.
    • Build the Docker image (make image).
    • Deploy the application (make install).

  2. Observe:

    • Verify deployment and service creation using kubectl get deployments and kubectl get services.
    • Access the HTTP service via the exposed port (e.g., through minikube service list).
    • Establish a TCP connection using telnet.

  3. Deploy New Version:

    • Modify the Git repository and commit changes.
    • Rebuild the Docker image (make image).
    • Deploy the new version (make install).

  4. Observe Draining:

    • Note that new requests are routed to the updated deployment.
    • Existing TCP connections remain on the old deployment.
    • Open a new TCP connection to see the new version's behavior.
    • Delete the older deployment (kubectl delete deployment <older-deployment>).

  5. Success!

Implementation

The Kubernetes configuration uses a Service selector that targets Deployments based on a color label. This label is generated from the Git commit hash, ensuring uniqueness for each deployment. The make install process dynamically updates the label, leading to a new deployment on every update. Cleanup of old deployments is left to the user.