Add Grafana Tempo distributed tracing with demo application

- Deploy Grafana Tempo in monolithic mode for distributed tracing
- Configure Tempo with OTLP receivers (gRPC:4317, HTTP:4318)
- Set up 10Gi filesystem storage with 7-day retention
- Integrate Tempo datasource in Grafana with traces-to-logs and traces-to-metrics correlation

- Update Grafana Alloy to collect and forward traces
- Add OTLP receiver configuration to alloy-values.yaml
- Configure batch processor for efficient trace forwarding to Tempo
- Patch Alloy service to expose OTLP ports 4317/4318

- Create demo tracing application (frontend, middleware, backend)
- Implement three-tier Python Flask application with OpenTelemetry instrumentation
- Auto-instrument with OpenTelemetry for Flask and requests libraries
- Push Docker images to private registry (registry.lan.buetow.org:30001)
- Deploy via Helm chart with Traefik ingress at tracing-demo.f3s.buetow.org

- Update Grafana configuration in prometheus/persistence-values.yaml
- Add Tempo to additionalDataSources for automatic provisioning

Files added:
- tempo/values.yaml: Tempo Helm chart configuration
- tempo/persistent-volumes.yaml: Storage configuration (10Gi PV/PVC)
- tempo/datasource-configmap.yaml: Grafana datasource with correlations
- tempo/Justfile: Installation automation
- tempo/README.md: Documentation

- tracing-demo/docker/frontend/: Python Flask frontend with OTel
- tracing-demo/docker/middleware/: Python Flask middleware with OTel
- tracing-demo/docker/backend/: Python Flask backend with OTel
- tracing-demo/helm-chart/: Kubernetes deployments, services, ingress
- tracing-demo/docker-image-Justfile: Docker build/push automation
- tracing-demo/Justfile: Helm deployment automation
- tracing-demo/README.md: Documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

5 files changed, 369 insertions, 0 deletions

diff --git a/f3s/tempo/Justfile b/f3s/tempo/Justfile
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+++ b/f3s/tempo/Justfile
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+# Grafana Tempo deployment automation
+# Following the pattern from Loki Justfile
+
+install:
+    helm repo add grafana https://grafana.github.io/helm-charts || true
+    helm repo update
+    kubectl apply -f persistent-volumes.yaml
+    helm install tempo grafana/tempo --namespace monitoring -f values.yaml
+    kubectl apply -f datasource-configmap.yaml
+
+uninstall:
+    kubectl delete -f datasource-configmap.yaml || true
+    helm uninstall tempo --namespace monitoring || true
+    kubectl delete -f persistent-volumes.yaml || true
+
+upgrade:
+    helm upgrade tempo grafana/tempo --namespace monitoring -f values.yaml
+    kubectl apply -f datasource-configmap.yaml
+
+status:
+    kubectl get pods -n monitoring -l app.kubernetes.io/name=tempo
+    kubectl get svc -n monitoring -l app.kubernetes.io/name=tempo
+    kubectl get pvc -n monitoring tempo-data-pvc
+
+logs:
+    kubectl logs -n monitoring -l app.kubernetes.io/name=tempo --tail=100 -f
+
+check:
+    @echo "Checking Tempo readiness..."
+    kubectl exec -n monitoring $(kubectl get pod -n monitoring -l app.kubernetes.io/name=tempo -o jsonpath='{.items[0].metadata.name}') -- wget -qO- http://localhost:3200/ready
+    @echo ""
+    @echo "Checking OTLP ports..."
+    kubectl exec -n monitoring $(kubectl get pod -n monitoring -l app.kubernetes.io/name=tempo -o jsonpath='{.items[0].metadata.name}') -- netstat -ln | grep -E ':(4317|4318|3200)'
diff --git a/f3s/tempo/README.md b/f3s/tempo/README.md
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+++ b/f3s/tempo/README.md
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+# Grafana Tempo - Distributed Tracing
+
+Grafana Tempo deployment for the f3s Kubernetes cluster in monolithic mode.
+
+## Overview
+
+- **Deployment Mode**: Monolithic (all components in one process)
+- **Storage Backend**: Filesystem (local storage on hostPath)
+- **Storage Size**: 10Gi
+- **Retention**: 7 days (168h)
+- **Namespace**: `monitoring`
+
+## Components
+
+- **Tempo**: Distributed tracing backend
+- **OTLP Receivers**: Accepts traces via gRPC (4317) and HTTP (4318)
+- **Query Frontend**: Query interface on port 3200
+- **Grafana Datasource**: Auto-discovered via ConfigMap label
+
+## Architecture
+
+```
+Applications → Alloy (OTLP collector) → Tempo → Grafana
+```
+
+## Installation
+
+```bash
+just install
+```
+
+This will:
+1. Add Grafana Helm repo and update
+2. Create PersistentVolume and PersistentVolumeClaim
+3. Install Tempo via Helm
+4. Create Grafana datasource ConfigMap
+
+## Configuration
+
+### values.yaml
+
+- Monolithic mode configuration
+- OTLP receivers on ports 4317 (gRPC) and 4318 (HTTP)
+- Local filesystem storage at `/var/tempo/traces`
+- Resource limits: 2Gi memory, 1 CPU
+
+### persistent-volumes.yaml
+
+- PV: `tempo-data-pv` at `/data/nfs/k3svolumes/tempo/data`
+- PVC: `tempo-data-pvc` (10Gi, ReadWriteOnce)
+
+### datasource-configmap.yaml
+
+- Auto-discovered by Grafana sidecar
+- Enables traces-to-logs correlation with Loki
+- Enables traces-to-metrics correlation with Prometheus
+- Enables service graph visualization
+
+## Grafana Integration
+
+The datasource is automatically discovered by Grafana through the ConfigMap with label `grafana_datasource: "1"`.
+
+To access traces in Grafana:
+1. Navigate to Explore
+2. Select "Tempo" datasource
+3. Use Search or TraceQL queries
+
+### Example TraceQL Queries
+
+```
+# Find all traces from demo app
+{ resource.service.namespace = "tracing-demo" }
+
+# Find slow requests (>200ms)
+{ duration > 200ms }
+
+# Find errors
+{ status = error }
+
+# Find traces from specific service
+{ resource.service.name = "frontend" }
+```
+
+## Verification
+
+Check that Tempo is running:
+```bash
+just status
+```
+
+Check Tempo readiness and OTLP ports:
+```bash
+just check
+```
+
+View logs:
+```bash
+just logs
+```
+
+## Sending Traces
+
+Applications should send traces to Alloy's OTLP receivers:
+- gRPC: `alloy.monitoring.svc.cluster.local:4317`
+- HTTP: `alloy.monitoring.svc.cluster.local:4318`
+
+Alloy forwards traces to Tempo at `tempo.monitoring.svc.cluster.local:4317`.
+
+## Maintenance
+
+### Upgrade
+
+```bash
+just upgrade
+```
+
+### Uninstall
+
+```bash
+just uninstall
+```
+
+### Check Storage Usage
+
+```bash
+kubectl exec -n monitoring $(kubectl get pod -n monitoring -l app.kubernetes.io/name=tempo -o jsonpath='{.items[0].metadata.name}') -- df -h /var/tempo
+```
+
+## Troubleshooting
+
+### Tempo pod not starting
+
+Check events:
+```bash
+kubectl describe pod -n monitoring -l app.kubernetes.io/name=tempo
+```
+
+Check PVC binding:
+```bash
+kubectl get pvc -n monitoring tempo-data-pvc
+```
+
+### No traces appearing
+
+1. Verify Alloy is forwarding traces:
+```bash
+kubectl logs -n monitoring -l app.kubernetes.io/name=alloy | grep -i tempo
+```
+
+2. Check Tempo logs:
+```bash
+just logs
+```
+
+3. Verify OTLP receivers are listening:
+```bash
+just check
+```
+
+### Grafana datasource not appearing
+
+1. Check ConfigMap exists:
+```bash
+kubectl get cm -n monitoring tempo-grafana-datasource --show-labels
+```
+
+2. Check Grafana sidecar logs:
+```bash
+kubectl logs -n monitoring $(kubectl get pod -n monitoring -l app.kubernetes.io/name=grafana -o jsonpath='{.items[0].metadata.name}') -c grafana-sc-datasources
+```
+
+3. Restart Grafana pod if needed:
+```bash
+kubectl delete pod -n monitoring -l app.kubernetes.io/name=grafana
+```
+
+## References
+
+- [Grafana Tempo Documentation](https://grafana.com/docs/tempo/latest/)
+- [Tempo Helm Chart](https://github.com/grafana/helm-charts/tree/main/charts/tempo)
+- [OpenTelemetry Protocol (OTLP)](https://opentelemetry.io/docs/specs/otlp/)
+- [TraceQL Query Language](https://grafana.com/docs/tempo/latest/traceql/)
diff --git a/f3s/tempo/datasource-configmap.yaml b/f3s/tempo/datasource-configmap.yaml
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+++ b/f3s/tempo/datasource-configmap.yaml
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+# Grafana Datasource ConfigMap for Tempo
+# Auto-discovered by Grafana sidecar via label grafana_datasource: "1"
+# Enables traces-to-logs and traces-to-metrics correlation
+
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: tempo-grafana-datasource
+  namespace: monitoring
+  labels:
+    grafana_datasource: "1"  # Must be string "1" for auto-discovery
+data:
+  tempo-datasource.yaml: |-
+    apiVersion: 1
+    datasources:
+    - name: "Tempo"
+      type: tempo
+      uid: tempo
+      url: http://tempo.monitoring.svc.cluster.local:3200
+      access: proxy
+      isDefault: false
+      editable: true
+      jsonData:
+        httpMethod: GET
+        # Enable traces-to-logs correlation with Loki
+        tracesToLogsV2:
+          datasourceUid: 'loki'
+          spanStartTimeShift: '-1h'
+          spanEndTimeShift: '1h'
+          filterByTraceID: false
+          filterBySpanID: false
+          tags: ['cluster', 'namespace', 'pod', 'app']
+        # Enable traces-to-metrics correlation with Prometheus
+        tracesToMetrics:
+          datasourceUid: 'prometheus'
+        # Enable service graph visualization
+        serviceMap:
+          datasourceUid: 'prometheus'
+        # Enable node graph for visualization
+        nodeGraph:
+          enabled: true
+        # Enable search
+        search:
+          hide: false
+        # Enable Loki search integration
+        lokiSearch:
+          datasourceUid: 'loki'
diff --git a/f3s/tempo/persistent-volumes.yaml b/f3s/tempo/persistent-volumes.yaml
new file mode 100644
index 0000000..fc4c378
--- /dev/null
+++ b/f3s/tempo/persistent-volumes.yaml
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+# Persistent Volume and Claim for Grafana Tempo trace storage
+# Following the pattern from Loki deployment
+# Storage: 10Gi at /data/nfs/k3svolumes/tempo/data
+
+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  name: tempo-data-pv
+spec:
+  capacity:
+    storage: 10Gi
+  volumeMode: Filesystem
+  accessModes:
+    - ReadWriteOnce
+  persistentVolumeReclaimPolicy: Retain
+  hostPath:
+    path: /data/nfs/k3svolumes/tempo/data
+    type: DirectoryOrCreate
+---
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: tempo-data-pvc
+  namespace: monitoring
+spec:
+  storageClassName: ""  # Empty for manual binding to PV
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 10Gi
diff --git a/f3s/tempo/values.yaml b/f3s/tempo/values.yaml
new file mode 100644
index 0000000..d118b63
--- /dev/null
+++ b/f3s/tempo/values.yaml
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+# Grafana Tempo - Monolithic Mode Configuration
+# Following the pattern from Loki SingleBinary deployment
+
+tempo:
+  # Retention policy for traces (7 days)
+  retention: 168h
+
+  # Storage configuration - Local filesystem backend
+  # This is required for monolithic mode
+  storage:
+    trace:
+      backend: local
+      local:
+        path: /var/tempo/traces
+      wal:
+        path: /var/tempo/wal
+
+  # Distributor configuration with OTLP receivers
+  # Bind to 0.0.0.0 to avoid Tempo 2.7+ localhost-only binding issue
+  receivers:
+    otlp:
+      protocols:
+        grpc:
+          endpoint: 0.0.0.0:4317
+        http:
+          endpoint: 0.0.0.0:4318
+
+  # Query frontend configuration
+  # Enabled by default in monolithic mode
+
+# Persistence configuration using hostPath PV
+# Matches the pattern from Loki deployment
+persistence:
+  enabled: true
+  size: 10Gi
+  storageClassName: ""  # Empty string for manual PV binding
+  accessModes:
+    - ReadWriteOnce
+
+# Service configuration
+# Expose OTLP ports and query endpoint
+service:
+  type: ClusterIP
+
+# Resource limits to prevent runaway resource usage
+# Adjusted for monolithic deployment
+resources:
+  limits:
+    cpu: 1000m
+    memory: 2Gi
+  requests:
+    cpu: 500m
+    memory: 1Gi
+
+# Security context following best practices
+# Using non-root user
+securityContext:
+  fsGroup: 10001
+  runAsUser: 10001
+  runAsGroup: 10001
+  runAsNonRoot: true
+
+# Disable components not needed in monolithic mode
+gateway:
+  enabled: false
+
+# Monitoring integration with Prometheus
+# Enables ServiceMonitor for automatic scraping
+serviceMonitor:
+  enabled: true
+  labels:
+    release: prometheus
+
+# Test pod disabled to reduce overhead
+test:
+  enabled: false