guestbook-service

The Guestbook sample from https://github.com/GoogleCloudPlatform/cloud-code-samples/tree/v1/python/python-guestbook

Details of the challenge: instructions.md

Features

• Python Flask frontend and backend services
• MongoDB database
• Kubernetes-native deployment using Helm charts
• Monitoring with Prometheus and Grafana
• Support for automated scaling with HorizontalPodAutoscaler
• Pod disruption budgets for high availability
• Ingress configuration for external access

Prerequisites

• Docker
• Kubernetes cluster (local using kind). A script can be used to start a local kind cluster and image registry
• Helm
• kubectl

Quick Start

1. Run provided Makefile:

make all

3. View available commands:

make help
Python Guestbook Application Management
======================================

Available commands:

  Command              Description
  all                   Set up cluster and deploy complete application
  deploy                Deploy to existing cluster without setup
  build                 Build all Docker images
  build-frontend        Build the frontend Docker image
  build-backend         Build the backend Docker image
  push                  Push all Docker images
  push-frontend         Push the frontend Docker image
  push-backend          Push the backend Docker image
  delete                Remove all application resources
  show-access           Display access URLs and credentials
  help                  Display available commands with descriptions
  verify-variables      Verify required variables are set
  setup-local-cluster   Setup local Kind cluster with registry and ingress
  delete-all            Delete Kind cluster
  verify-registry       Verify registry is accessible

Examples:
  make setup-local-cluster   # Set up a local Kind cluster with registry and ingress
  make all                   # Set up cluster and deploy complete application
  make deploy                # Deploy to existing cluster without cluster setup
  make delete                # Clean up all resources
  make delete-all            # Clean up all resources and delete Kind cluster

Configuration:
  REGISTRY = localhost:5000
  VERSION = [VERSION]

Access the services

• Frontend: http://frontend.localhost
• Grafana: http://grafana.localhost
• Prometheus: http://prometheus.localhost
• Alertmanager: http://alertmanager.localhost

Note: The above URLs assume you are using the default ingress configuration with a local kind cluster. Update the hostnames in the respective Helm values files if using a different domain.

Architecture Diagram

Helm Chart Structure

├── charts
│   ├── guestbook-backend
│   │   ├── Chart.yaml
│   │   ├── README.md
│   │   ├── README.md.gotmpl
│   │   ├── dashboards
│   │   │   └── guestbook-backend.json
│   │   ├── templates
│   │   │   ├── NOTES.txt
│   │   │   ├── _helpers.tpl
│   │   │   ├── configmap.yaml
│   │   │   ├── deployment.yaml
│   │   │   ├── grafana-dashboards.yaml
│   │   │   ├── hpa.yaml
│   │   │   ├── pdb.yaml
│   │   │   ├── prometheus-rules.yaml
│   │   │   ├── secret.yaml
│   │   │   ├── service.yaml
│   │   │   ├── serviceaccount.yaml
│   │   │   └── servicemonitor.yaml
│   │   └── values.yaml
│   ├── guestbook-frontend
│   │   ├── Chart.yaml
│   │   ├── README.md
│   │   ├── README.md.gotmpl
│   │   ├── dashboards
│   │   │   └── guestbook-frontend.json
│   │   ├── templates
│   │   │   ├── NOTES.txt
│   │   │   ├── _helpers.tpl
│   │   │   ├── deployment.yaml
│   │   │   ├── grafana-dashboard.yaml
│   │   │   ├── hpa.yaml
│   │   │   ├── ingress.yaml
│   │   │   ├── pdb.yaml
│   │   │   ├── prometheus-rules.yaml
│   │   │   ├── service.yaml
│   │   │   ├── serviceaccount.yaml
│   │   │   └── servicemonitor.yaml
│   │   └── values.yaml
│   ├── kube-prometheus-stack
│   │   ├── README.md
│   │   └── values.yaml
│   └── mongodb
│       ├── README.md
│       ├── mongodb-exporter.yaml
│       └── values.yaml

Each Helm Chart folder includes a README.md file that provides detailed information about the chart.

• guestbook-backend
• guestbook-frontend
• MongoDB
• Kube-Prometheus-Stack

Configuration

Each component can be configured via their respective values.yaml files. See individual chart READMEs for detailed configuration options.

Testing Scaling and Alerts

The examples below are for guestbook-frontend. Please adjust the name of the service and namespace accordingly if needed.

Scale Down Test

1. Scale down the frontend deployment:

kubectl scale deployment guestbook-frontend --replicas=1 -n guestbook-frontend

2. Check the HorizontalPodAutoscaler status:

kubectl get hpa guestbook-frontend -n guestbook-frontend

3. Monitor pod status:

kubectl get pods -n guestbook-frontend -l tier=frontend

Checking Prometheus Alerts

1. Scale down the frontend deployment:

kubectl scale deployment guestbook-frontend --replicas=0 -n guestbook-frontend

2. Look for the following alerts:

   • GuestbookFrontendNoPods: Triggers when frontend pods are not available

3. To resolve the alerts, scale the deployment back up:

kubectl scale deployment guestbook-frontend --replicas=2 -n default