k8s-telepresence-demo

The purpose of this demo is to showcase how can we debug a Kubernetes service locally using Telepresence. There is a minimal client-server Kubernetes application, with a React (Javascript) front-end, and a SpringBoot (Java) back-end. The application can be packaged in a Helm chart.

Pre-requisites

You need to have Docker, Kubectl, Minikube, NGINX Ingress Controller, Helm, and Telepresence installed.

Installation

• To build the demo (build docker images and package the helm chart) : .\gradlew buildApp
• To build and deploy into a Kubernetes cluster: .\gradlew deployApp

Run the server locally

• After deploying the application to the Kubernetes cluster:
  • Go to the server folder: $ cd server
  • Build a local docker image: $ docker build -t k8s-demo-server-img .
  • Swap the remote deployment with the local Docker image: $ telepresence --swap-deployment k8s-demo:server --expose 8000:8002 --docker-run --rm -it k8s-demo-server-img
  • If you want to remote debug the back-end: $ telepresence --swap-deployment k8s-demo:server --expose 8000:8002 --docker-run --rm -it -p 5005:5005 -e JAVA_TOOL_OPTIONS=-agentlib:jdwp=transport=dt_socket,address=5005,server=y,suspend=y k8s-demo-server-img
  • In case you are using a Kubernetes client: telepresence --mount /tmp/known --swap-deployment k8s-demo:server --expose 8000:8002 --docker-run --rm -it -v=/tmp/known/var/run/secrets:/var/run/secrets k8s-demo-server-img
  • All in one!: telepresence --mount /tmp/known --swap-deployment k8s-demo:server --expose 8000:8002 --docker-run --rm -it -p 5005:5005 -e JAVA_TOOL_OPTIONS=-agentlib:jdwp=transport=dt_socket,address=5005,server=y,suspend=y -v=/tmp/known/var/run/secrets:/var/run/secrets k8s-demo-server-img

Project Structure

|-- client/
|   |-- src/: front-end source code.
|   |-- Dockerfile: front-end Docker image recipe.
|   |-- build.gradle: build Docker image task.
|   |-- package.json: project metadata.
|-- server/
|   |-- build/: build directory (jar file destination).
|   |-- src/: back-end source code.
|   |-- Dockerfile: back-end Docker image recipe.
|   |-- build.gradle: build Docker image task.
|-- helm/
|   |-- chart/
|   |   |-- templates/: parameterizable Kubernetes objects.
|   |   |-- Chart.yaml: name and version information.
|   |   |-- values.yaml: values to feed the templates.
|   |-- build.gradle: helm chart package task.
|-- build.gradle: build and deploy tasks.
|-- settings.gradle

Kubernetes Architecture

• Client and Server are running in different Docker containers, inside a single pod.
• A service is exposing the pod inside the Kubernetes cluster.
• The ingress allows access to the service from outside the Kubernetes cluster.

Demo

To access the application:

• Front-end: http://<hostname>/client
• Backend:
  • http://<hostname>/server
  • http://<hostname>/server/services

Authors:

• Leonardo Coelho - leonardo.coelho@ua.pt