Network Architecture¶

The WebGrip platform implements a multi-layered network architecture that provides secure, scalable, and observable connectivity for applications and platform services.

Network Overview¶

The platform network architecture follows Kubernetes networking principles with additional layers for ingress, service mesh capabilities, and security enforcement.

Network Layers¶

1. External Network Layer¶

Purpose: Handles external traffic routing and global load balancing

Components: - Internet Gateway: Public internet access point - DNS: Domain name resolution and traffic distribution - CDN: Content delivery network for static assets (if configured)

Traffic Flow:

1	`External Users → DNS Resolution → Load Balancer → Ingress Controller`

2. Ingress Layer¶

Technology: Traefik Configuration: ops/helm/030-ingress-controllers/ingress-traefik/

The ingress layer provides:

HTTP/HTTPS Termination: TLS certificate management and SSL termination
Request Routing: Path and host-based routing to backend services
Load Balancing: Traffic distribution across healthy service instances
Middleware: Authentication, rate limiting, and traffic modification

Traefik Configuration:

Key Features: - Automatic Service Discovery: Kubernetes provider for dynamic configuration - Certificate Automation: Integration with cert-manager - Observability: Built-in metrics and tracing capabilities - Custom Middleware: ops/helm/030-ingress-controllers/ingress-traefik-custom-middlewares/

3. Pod Network (CNI)¶

Technology: Kubernetes Container Network Interface (CNI) Implementation: Cloud provider managed (DigitalOcean)

Pod networking provides:

Pod-to-Pod Communication: Direct IP connectivity between pods across nodes
IP Address Management: Automatic IP allocation from cluster CIDR
Network Isolation: Namespace-based network segmentation
Network Policies: Fine-grained traffic control rules

Pod Communication Patterns:

Network Address Ranges: | Network Type | CIDR Range | Purpose | |-------------|------------|---------| | Cluster CIDR | 10.244.0.0/16 | Pod IP addresses | | Service CIDR | 10.96.0.0/12 | Service virtual IPs | | Node CIDR | 10.0.0.0/16 | Node infrastructure IPs |

Assumption: CIDR ranges are typical Kubernetes defaults. Actual ranges should be verified in cluster configuration with kubectl cluster-info dump | grep -i cidr or by checking cluster provider settings.

📝 Assumption: CIDR ranges are typical defaults. Actual ranges should be verified in cluster configuration.

4. Service Network¶

Technology: Kubernetes Services Types: ClusterIP, NodePort, LoadBalancer, ExternalName

Service networking provides:

Service Discovery: DNS-based service name resolution
Load Balancing: Traffic distribution across healthy endpoints
Session Affinity: Sticky sessions when required
Health Checking: Endpoint health monitoring and removal

Service Types in Platform:

Service Discovery Example:

# DNS resolution within cluster
curl http://grafana.grafana-stack.svc.cluster.local:80

# Short name resolution (same namespace)
curl http://grafana:80

# Cross-namespace resolution  
curl http://traefik.ingress-traefik.svc.cluster.local:80

Network Security¶

Network Policies¶

Purpose: Implement microsegmentation and zero-trust networking

Default Policy: Deny all traffic, allow specific flows

Example Network Policy Structure:

# Allow ingress traffic to web tier from ingress controller
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: web-tier-ingress
spec:
  podSelector:
    matchLabels:
      tier: web
  policyTypes:
  - Ingress
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          name: ingress-traefik
    ports:
    - protocol: TCP
      port: 8080

Network Policy Categories: - Ingress Policies: Control incoming traffic to pods - Egress Policies: Control outgoing traffic from pods
- Namespace Isolation: Restrict cross-namespace communication - Platform Service Access: Allow access to monitoring and logging

TLS and Certificate Management¶

Technology: cert-manager Configuration: ops/helm/010-cert-manager/

Certificate management provides:

Automatic Certificate Provisioning: Let's Encrypt integration
Certificate Rotation: Automatic renewal before expiry
Wildcard Certificates: Domain and subdomain coverage
Certificate Distribution: Automatic distribution to ingress controllers

Certificate Issuers: - Cluster Issuers: ops/helm/020-cluster-issuers/certificate-cluster-issuer-traefik/ - Let's Encrypt Production: For production workloads - Let's Encrypt Staging: For testing and validation

Service Mesh Capabilities¶

While not implementing a full service mesh, the platform provides service mesh-like capabilities through:

Traffic Management¶

Traefik Middleware: ops/helm/030-ingress-controllers/ingress-traefik-custom-middlewares/

Request Routing: Path and header-based routing
Traffic Splitting: A/B testing and canary deployments
Circuit Breaking: Automatic failure handling
Rate Limiting: Request throttling and DDoS protection

Observability¶

Integration Points: - Metrics: Prometheus metrics from network components - Tracing: Distributed tracing headers and propagation - Logging: Access logs and audit trails - Health Checks: Endpoint health monitoring

Network Monitoring¶

Monitoring Components¶

Traffic Monitoring: - Ingress Metrics: Request rates, response times, error rates - Service Metrics: Endpoint health, connection counts - Pod Network Metrics: Bandwidth utilization, packet loss - DNS Metrics: Resolution times, failure rates

Key Metrics Collected: | Metric Category | Examples | Dashboard | |----------------|----------|-----------| | Ingress Traffic | Request rate, latency, error rate | Traefik Dashboard | | Service Health | Endpoint availability, response time | Service Dashboard | | Network Performance | Bandwidth, packet loss, connection counts | Network Dashboard | | Security Events | Failed connections, certificate issues | Security Dashboard |

Network Troubleshooting¶

Common Tools and Commands:

# Check service endpoints
kubectl get endpoints -A

# Test service connectivity
kubectl run -it --rm debug --image=busybox --restart=Never -- sh
# Inside pod: nslookup service-name

# Check network policies
kubectl get networkpolicies -A

# View ingress status
kubectl get ingress -A

# Check certificate status
kubectl get certificates -A

Troubleshooting Workflows: 1. Service Discovery Issues: Check DNS resolution and service endpoints 2. Connectivity Problems: Verify network policies and security groups 3. Certificate Issues: Check cert-manager logs and certificate status 4. Performance Issues: Review traffic patterns and resource utilization

Network Access Patterns¶

Application Access Patterns¶

Administrative Access¶

Management Interfaces: - Kubernetes API: kubectl and dashboard access - Grafana: make view-grafana - Monitoring dashboards - Traefik Dashboard: make view-traefik - Ingress status - Prometheus: Direct metrics access for troubleshooting

Access Control: - RBAC: Role-based access control for cluster resources - Network Policies: Restrict administrative interface access - VPN/Bastion: Secure access for administrative operations

Performance Optimization¶

Network Performance Tuning¶

Optimization Strategies: - Connection Pooling: Reuse connections for backend services - HTTP/2: Enable HTTP/2 for improved multiplexing - Compression: Gzip/Brotli compression for responses - Caching: Edge caching and CDN integration

Resource Limits:

# Example resource limits for network components
resources:
  requests:
    memory: "256Mi"
    cpu: "100m"
  limits:
    memory: "512Mi" 
    cpu: "500m"

Capacity Planning¶

Network Capacity Metrics: - Bandwidth Utilization: Monitor node and pod network usage - Connection Limits: Track concurrent connections per service - Latency Targets: Maintain acceptable response times - Throughput Requirements: Plan for peak traffic scenarios

Next Steps¶

Explore related network and infrastructure topics:

🔒 Security Model
Understand security controls, access management, and network security policies

📊 Resource Management
Learn about resource allocation, scaling, and capacity planning

🔧 Ingress & Load Balancing
Deep dive into Traefik configuration and traffic management

📈 Monitoring & Observability
Explore network monitoring, metrics, and troubleshooting tools

🌐 Network Evolution: Network architecture changes should be documented in Architecture Decision Records (ADRs) due to their impact on security and performance.