Hub Web & API¶

Overview¶

Hub is the main application suite consisting of a Blazor web frontend and .NET API backend.

Architecture¶

graph LR
    subgraph External
        Users[Users]
        CF[Cloudflare]
    end

    subgraph Kubernetes
        subgraph hub namespace
            Web[Hub Web]
            API[Hub API]
        end

        subgraph databases namespace
            Mongo[(MongoDB)]
            Influx[(InfluxDB)]
            ES[(Elasticsearch)]
        end
    end

    Users --> CF
    CF --> Web
    Web --> API
    API --> Mongo
    API --> Influx
    API --> ES

Components¶

Hub Web¶

Property	Value
Technology	Blazor Server
Framework	.NET 8
Port	80
URL	ajandrews.pro

Hub API¶

Property	Value
Technology	ASP.NET Core Web API
Framework	.NET 8
Port	8080
URL	api.ajandrews.pro

Deployment¶

Kubernetes Resources¶

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hub-web
  namespace: hub
spec:
  replicas: 2
  template:
    spec:
      containers:
      - name: hub-web
        image: ajxfear/hub-web:latest
        ports:
        - containerPort: 80
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: hub-api
  namespace: hub
spec:
  replicas: 2
  template:
    spec:
      containers:
      - name: hub-api
        image: ajxfear/hub-api:latest
        ports:
        - containerPort: 8080

API Endpoints¶

Weather Service¶

GET /api/weather/current
GET /api/weather/forecast

Metrics¶

GET /metrics - Prometheus metrics
GET /health - Health check
GET /ready - Readiness check

Dependencies¶

Database Connections¶

Database	Purpose
MongoDB	Document storage
InfluxDB	Time series metrics
Elasticsearch	Search and logging

External Services¶

Weather API integration
Metrics push to InfluxDB

Configuration¶

Environment Variables¶

Variable	Description
`MONGODB_CONNECTION`	MongoDB connection string
`INFLUXDB_URL`	InfluxDB endpoint
`INFLUXDB_TOKEN`	InfluxDB auth token
`ELASTICSEARCH_URL`	Elasticsearch endpoint

ConfigMaps¶

apiVersion: v1
kind: ConfigMap
metadata:
  name: hub-config
  namespace: hub
data:
  ASPNETCORE_ENVIRONMENT: "Production"
  ELASTICSEARCH_URL: "http://elasticsearch.monitoring:9200"

Monitoring¶

Metrics¶

The API exposes Prometheus metrics:

Metric	Description
`http_requests_total`	Total HTTP requests
`http_request_duration_seconds`	Request latency histogram
`hub_weather_requests_total`	Weather API calls

Health Checks¶

livenessProbe:
  httpGet:
    path: /health
    port: 8080
  initialDelaySeconds: 10
  periodSeconds: 30

readinessProbe:
  httpGet:
    path: /ready
    port: 8080
  initialDelaySeconds: 5
  periodSeconds: 10

CI/CD Pipeline¶

GitHub Actions¶

Push to main branch
Build Docker images
Push to Docker Hub
Update k8s manifests
ArgoCD syncs changes

Image Tags¶

Tag	Description
`latest`	Most recent build
`sha-xxxxxx`	Specific commit

Scaling¶

Horizontal Pod Autoscaler¶

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: hub-api
  namespace: hub
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: hub-api
  minReplicas: 2
  maxReplicas: 5
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 70

Rate Limiting¶

The API includes rate limiting middleware to prevent abuse:

Limit	Value
Per Minute	60 requests
Per Hour	1000 requests

Excluded Endpoints¶

The following endpoints are excluded from rate limiting to prevent health probe failures:

/health - Kubernetes liveness/readiness probes
/metrics - Prometheus scraping
/ready - Readiness checks
/live - Liveness checks

Rate Limit and Health Probes

If health endpoints are not excluded from rate limiting, Kubernetes probes and Prometheus scraping can trigger rate limits, causing pod restart loops.

Troubleshooting¶

Common Issues¶

Issue	Cause	Resolution
502 Bad Gateway	Pod not ready	Check readiness probe
Slow responses	High load	Check CPU/memory usage
DB connection failed	Network/auth	Verify connection string
429 Too Many Requests	Rate limit exceeded	Wait 60s or check excluded paths
Pod restart loop	Health probes rate limited	Ensure /health excluded from rate limiting