prometheus-grafana

# prometheus.yml
global:
  scrape_interval: 15s
  evaluation_interval: 15s
 
alerting:
  alertmanagers:
    - static_configs:
        - targets:
            - alertmanager:9093
 
rule_files:
  - /etc/prometheus/rules/*.yml
 
scrape_configs:
  - job_name: 'prometheus'
    static_configs:
      - targets: ['localhost:9090']
 
  - job_name: 'node'
    static_configs:
      - targets:
          - 'node-exporter:9100'
 
  - job_name: 'applications'
    static_configs:
      - targets:
          - 'app1:8080'
          - 'app2:8080'
    metrics_path: /metrics

# Add Prometheus community Helm repo
helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
 
# Install kube-prometheus-stack
helm install prometheus prometheus-community/kube-prometheus-stack \
  --namespace monitoring \
  --create-namespace \
  --set grafana.adminPassword=admin

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: myapp
  namespace: monitoring
spec:
  selector:
    matchLabels:
      app: myapp
  endpoints:
    - port: metrics
      interval: 30s
      path: /metrics
  namespaceSelector:
    matchNames:
      - default

# Current CPU usage
node_cpu_seconds_total{mode="idle"}
 
# Rate of HTTP requests per second
rate(http_requests_total[5m])
 
# Average response time
avg(http_request_duration_seconds_sum / http_request_duration_seconds_count)
 
# Memory usage percentage
(1 - (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes)) * 100

# Sum requests by status code
sum by (status_code) (rate(http_requests_total[5m]))
 
# Average CPU by instance
avg by (instance) (rate(node_cpu_seconds_total{mode!="idle"}[5m]))
 
# Top 5 endpoints by request count
topk(5, sum by (endpoint) (rate(http_requests_total[5m])))
 
# 95th percentile latency
histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m]))

# Compare to 1 hour ago
http_requests_total - http_requests_total offset 1h
 
# Predict disk space in 4 hours
predict_linear(node_filesystem_avail_bytes[1h], 4 * 3600)
 
# Changes in last 5 minutes
changes(up[5m])
 
# Average over 24 hours
avg_over_time(http_requests_total[24h])

# rules/alerts.yml
groups:
  - name: application
    rules:
      - alert: HighErrorRate
        expr: |
          sum(rate(http_requests_total{status=~"5.."}[5m]))
          / sum(rate(http_requests_total[5m])) > 0.05
        for: 5m
        labels:
          severity: critical
        annotations:
          summary: "High error rate detected"
          description: "Error rate is {{ $value | humanizePercentage }}"
 
      - alert: ServiceDown
        expr: up == 0
        for: 1m
        labels:
          severity: critical
        annotations:
          summary: "Service {{ $labels.instance }} is down"
 
      - alert: HighMemoryUsage
        expr: |
          (1 - (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes)) > 0.9
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High memory usage on {{ $labels.instance }}"
          description: "Memory usage is {{ $value | humanizePercentage }}"
 
      - alert: DiskSpaceLow
        expr: |
          (node_filesystem_avail_bytes{mountpoint="/"} / node_filesystem_size_bytes{mountpoint="/"}) < 0.1
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "Disk space low on {{ $labels.instance }}"

# alertmanager.yml
global:
  resolve_timeout: 5m
  slack_api_url: 'https://hooks.slack.com/services/xxx'
 
route:
  receiver: 'slack-notifications'
  group_by: ['alertname', 'severity']
  group_wait: 30s
  group_interval: 5m
  repeat_interval: 4h
  routes:
    - match:
        severity: critical
      receiver: 'pagerduty'
 
receivers:
  - name: 'slack-notifications'
    slack_configs:
      - channel: '#alerts'
        send_resolved: true
        title: '{{ .Status | toUpper }}: {{ .CommonAnnotations.summary }}'
        text: '{{ .CommonAnnotations.description }}'
 
  - name: 'pagerduty'
    pagerduty_configs:
      - service_key: 'xxx'
        severity: critical

{
  "dashboard": {
    "title": "Application Metrics",
    "panels": [
      {
        "title": "Request Rate",
        "type": "graph",
        "targets": [
          {
            "expr": "sum(rate(http_requests_total[5m])) by (status_code)",
            "legendFormat": "{{ status_code }}"
          }
        ],
        "gridPos": {"x": 0, "y": 0, "w": 12, "h": 8}
      },
      {
        "title": "Latency P95",
        "type": "gauge",
        "targets": [
          {
            "expr": "histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m]))"
          }
        ],
        "gridPos": {"x": 12, "y": 0, "w": 6, "h": 8}
      }
    ]
  }
}

# grafana/provisioning/dashboards/dashboards.yml
apiVersion: 1
 
providers:
  - name: 'default'
    orgId: 1
    folder: ''
    type: file
    disableDeletion: false
    updateIntervalSeconds: 30
    options:
      path: /var/lib/grafana/dashboards

# grafana/provisioning/datasources/prometheus.yml
apiVersion: 1
 
datasources:
  - name: Prometheus
    type: prometheus
    access: proxy
    url: http://prometheus:9090
    isDefault: true
    editable: false

# rules/recording.yml
groups:
  - name: aggregations
    interval: 30s
    rules:
      - record: job:http_requests:rate5m
        expr: sum by (job) (rate(http_requests_total[5m]))
 
      - record: instance:node_cpu:avg_rate5m
        expr: |
          avg by (instance) (
            rate(node_cpu_seconds_total{mode!="idle"}[5m])
          )
 
      - record: job:http_latency:p95
        expr: |
          histogram_quantile(0.95,
            sum by (job, le) (rate(http_request_duration_seconds_bucket[5m]))
          )

import (
    "github.com/prometheus/client_golang/prometheus"
    "github.com/prometheus/client_golang/prometheus/promhttp"
)
 
var httpRequests = prometheus.NewCounterVec(
    prometheus.CounterOpts{
        Name: "http_requests_total",
        Help: "Total HTTP requests",
    },
    []string{"method", "endpoint", "status"},
)
 
func init() {
    prometheus.MustRegister(httpRequests)
}
 
// Expose metrics endpoint
http.Handle("/metrics", promhttp.Handler())

const client = require('prom-client');
 
const httpRequests = new client.Counter({
  name: 'http_requests_total',
  help: 'Total HTTP requests',
  labelNames: ['method', 'endpoint', 'status']
});
 
// Middleware
app.use((req, res, next) => {
  res.on('finish', () => {
    httpRequests.inc({
      method: req.method,
      endpoint: req.path,
      status: res.statusCode
    });
  });
  next();
});
 
// Expose metrics
app.get('/metrics', async (req, res) => {
  res.set('Content-Type', client.register.contentType);
  res.end(await client.register.metrics());
});