​
Architecture

All services run inside Docker containers on a single Ubuntu server, connected via the coderz-net Docker bridge network. External traffic enters through Nginx on port 80 or directly to each service port.

​
System Diagram

                          INTERNET
                             │
                    ┌────────▼────────┐
                    │   Nginx :80     │  ← Landing Page / API Gateway
                    │  + Redis Cache  │
                    └────────┬────────┘
                             │
          ┌──────────────────┼──────────────────┐
          │                  │                  │
   ┌──────▼──────┐   ┌───────▼──────┐   ┌──────▼──────┐
   │  .NET API   │   │  Python API  │   │  Static     │
   │   :5050     │   │    :8888     │   │  Assets     │
   └──────┬──────┘   └───────┬──────┘   └─────────────┘
          │                  │
          └──────────┬────────┘
                     │
             ┌───────▼────────┐
             │  PostgreSQL    │
             │    :5433       │
             └────────────────┘

  ┌─────────────── MONITORING ──────────────────┐
  │                                             │
  │  Prometheus :9090 ◄── Node Exporter :9100   │
  │       │            ◄── cAdvisor :8080        │
  │       │            ◄── .NET API metrics      │
  │       │            ◄── k3s API server        │
  │       ▼                                     │
  │  Grafana :3000 ──► Alerts ──► Email (SMTP)  │
  └─────────────────────────────────────────────┘

  ┌─────────────── LOGGING ─────────────────────┐
  │                                             │
  │  Promtail ──► Loki :3100 ──► Grafana        │
  │                                             │
  │  Filebeat ──► Logstash :5044 ──► ES :9200   │
  │                                   │         │
  │                              Kibana :5601   │
  └─────────────────────────────────────────────┘

  ┌─────────────── ORCHESTRATION ───────────────┐
  │                                             │
  │  Prefect :4200                              │
  │    ├── system-health (every 5min)           │
  │    ├── services-health (every 10min)        │
  │    ├── threshold-alerts (every 15min)       │
  │    ├── k8s-health (every 15min)             │
  │    ├── docker-restart-monitor (every 10min) │
  │    ├── daily-summary (06:00 UTC)            │
  │    └── weekly-cleanup (Sunday 02:00 UTC)    │
  └─────────────────────────────────────────────┘

  ┌─────────────── KUBERNETES ──────────────────┐
  │                                             │
  │  k3s cluster                                │
  │    ├── coderz-web (2 replicas)              │
  │    └── kube-state-metrics                   │
  └─────────────────────────────────────────────┘

​
Network Layout

All containers share the coderz-net Docker bridge network. This means:
  • Services communicate by container name (e.g., coderz-dotnet-api:8080)
  • No external exposure unless a port is explicitly mapped
  • Redis, PostgreSQL, and Loki are internal-only by default

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Data Flow: API Request

Client
  │
  ▼
Nginx (API Gateway)
  ├── Check Redis cache → HIT → return cached response
  │
  ├── MISS → forward to backend API
  │              │
  │              ├── .NET API or Python API
  │              │     │
  │              │     └── PostgreSQL query
  │              │
  │              └── Response → cache in Redis → return to client
  │
  └── Log request → Logstash → Elasticsearch → Kibana

​
Data Flow: Metrics

Host OS / Docker / k3s
  │
  ├── Node Exporter :9100  (CPU, RAM, Disk, Network)
  ├── cAdvisor :8080       (container-level metrics)
  ├── .NET API /metrics    (app-level metrics)
  └── k3s API server       (Kubernetes metrics)
         │
         ▼
    Prometheus :9090
    (scrapes every 15s, stores 30 days)
         │
         ▼
    Grafana :3000
    (dashboards + alert rules)
         │
         ▼
    Postfix SMTP → Gmail → aboodm7med1995@gmail.com

​
Port Reference

PortServiceAccessible From
80NginxPublic
3000GrafanaPublic
3100LokiInternal
3333Mintlify DocsPublic
4200Prefect UIPublic
5050.NET APIPublic
5080pgAdminPublic
5433PostgreSQLInternal
5601KibanaPublic
8080cAdvisorInternal
8888Web APIPublic
9000k6 RunnerPublic
9090PrometheusPublic
9100Node ExporterInternal
9200ElasticsearchInternal