Three-Tier Application Demo

Overview

A demo application with a three-tier architecture (Frontend → Backend → Database) designed to:

1. Show the capabilities of the cloud platform
2. Demonstrate how Network Policies work
3. Example of integration with Dex authentication system
4. Testing the interaction of components in a virtualized environment

Application Structure

• Project: demo-db
  • Database
    • VM: db (PostgreSQL)
• Project: demo-app
  • Frontend
    • VM: frontend (Bootstrap app)
    • Pod: frontend (Bootstrap app)
  • Backend
    • VM: backend-a (Flask + Gunicorn)
    • VM: backend-b (Flask + Gunicorn)

Component interaction is restricted by network policies. Application access requires authentication via Dex.

Access System

User	Role	Access Rights
demo-user@flant.com	Application User	Access via web interface
demo-db-admin@flant.com	Project Administrator demo-db	Full VM access with PostgreSQL
demo-app-admin@flant.com	Project Administrator demo-app	Management of all application components

Translated with DeepL.com (free version)

Repository Structure

• /apps - Frontend and backend source code
• /k8s - Kubernetes deployment manifests
• /ansible - Ansible playbooks for VM management

Requirements

Required d8 Modules

Ensure the following d8 modules are enabled and configured:

• admission-policy-engine
• cni-cilium
• console
• multitenancy-manager
• service-with-healthchecks
• user-authn
• virtualization
• operator-argo (required for ArgoCD installation)

Installation-Specific Requirements

For Option 1 (Manual Installation via Task):

• task
• yq
• ansible
• d8 (v0.27.0+ for ansible-inventory support)

Installation

Option 1: Manual Installation via Task

1. Create a .env file with infrastructure settings:

PASSWORD=password
FQDN=demo.example.com

2. Generate SSH keys for VM access:

task ssh-gen

3. Deploy the application:

task deploy

4. Uninstall the application:

task undeploy

Option 2: ArgoCD Installation

1. Apply the ApplicationSet:

task argocd:apply

2. ArgoCD will automatically create and sync applications for demo-app and demo-db namespaces.

3. To remove, delete the ApplicationSet:

task argocd:delete

How to connect to VM

Via Task (SSH)

task ssh:frontend    # Connect to frontend VM
task ssh:backend-a   # Connect to backend-a VM
task ssh:backend-b   # Connect to backend-b VM
task ssh:db          # Connect to database VM

Via d8 CLI

SSH:

d8 v ssh -n demo-app cloud@<vmname> -i ./tmp/demo --local-ssh

Console:

d8 v console -n demo-app <vmname>

Ansible Management

The project includes Ansible playbooks for automated VM management. Uses d8 v ansible-inventory for dynamic inventory discovery.

Check VM uptime:

task ansible:uptime

Update packages on all VMs:

task ansible:update

Run security checks:

task ansible:security-check