Set Up Uptime Checks

Monitor service availability from external vantage points and prevent SSL certificate expirations.

When to Use

• Monitoring customer-facing endpoints (APIs, websites)
• Tracking SSL certificate expiration
• Validating service availability from multiple regions
• Creating public status pages
• Meeting SLA requirements for uptime reporting

Inputs

• Required: List of HTTP/HTTPS endpoints to monitor
• Required: Prometheus instance for metric collection
• Optional: Multiple geographic probe locations
• Optional: Status page tool (Statuspage.io, Cachet, custom)
• Optional: Alert notification channels (PagerDuty, Slack)

Procedure

See Extended Examples for complete configuration files and templates.

Step 1: Deploy Blackbox Exporter

Install Blackbox Exporter via Docker or Kubernetes:

# Docker deployment
docker run -d \
  --name blackbox-exporter \
  -p 9115:9115 \
  -v $(pwd)/blackbox.yml:/etc/blackbox_exporter/config.yml \
  prom/blackbox-exporter:latest \
  --config.file=/etc/blackbox_exporter/config.yml

Kubernetes deployment:

# blackbox-exporter-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: blackbox-exporter
  namespace: monitoring
spec:
  replicas: 1
  selector:
    matchLabels:
      app: blackbox-exporter
  template:
    metadata:
      labels:
        app: blackbox-exporter
    spec:
      containers:
      - name: blackbox-exporter
        image: prom/blackbox-exporter:latest
        ports:
        - containerPort: 9115
        volumeMounts:
        - name: config
          mountPath: /etc/blackbox_exporter
      volumes:
      - name: config
        configMap:
          name: blackbox-exporter-config
---
apiVersion: v1
kind: Service
metadata:
  name: blackbox-exporter
  namespace: monitoring
spec:
  selector:
    app: blackbox-exporter
  ports:
  - port: 9115
    targetPort: 9115

Got: Blackbox Exporter running and accessible on port 9115.

If fail: Check firewall rules, ensure config volume is mounted correctly.

Step 2: Configure Blackbox Modules

Create blackbox.yml with various probe types:

# blackbox.yml
modules:
  # Basic HTTP 200 check
  http_2xx:
    prober: http
    timeout: 5s
    http:
      valid_status_codes: [200]
      method: GET
      follow_redirects: true
      preferred_ip_protocol: "ip4"

  # HTTP with authentication
  http_2xx_auth:
    prober: http
    timeout: 5s
    http:
      valid_status_codes: [200]
      method: GET
      headers:
        Authorization: "Bearer ${AUTH_TOKEN}"

  # API health check (expects JSON response)
  http_json_health:
    prober: http
    timeout: 5s
    http:
      valid_status_codes: [200]
      method: GET
      fail_if_body_not_matches_regexp:
        - '"status":"healthy"'

  # SSL certificate check
  http_2xx_ssl:
    prober: http
    timeout: 5s
    http:
      valid_status_codes: [200]
      method: GET
      tls_config:
        insecure_skip_verify: false
      fail_if_ssl_not_present: true

  # TCP port check (e.g., database)
  tcp_connect:
    prober: tcp
    timeout: 5s
    tcp:
      preferred_ip_protocol: "ip4"

  # ICMP ping
  icmp:
    prober: icmp
    timeout: 5s
    icmp:
      preferred_ip_protocol: "ip4"

  # DNS resolution check
  dns_google:
    prober: dns
    timeout: 5s
    dns:
      query_name: "google.com"
      query_type: "A"
      valid_rcodes:
        - NOERROR

Load config into Kubernetes:

kubectl create configmap blackbox-exporter-config \
  -n monitoring \
  --from-file=blackbox.yml \
  --dry-run=client -o yaml | kubectl apply -f -

Got: Multiple probe modules configured for different check types.

If fail: Validate YAML syntax. Check Blackbox Exporter logs for config errors.

Step 3: Configure Prometheus Scrape

Add Blackbox targets to Prometheus config:

# prometheus.yml
scrape_configs:
  # Blackbox exporter itself
  - job_name: 'blackbox-exporter'
    static_configs:
      - targets: ['blackbox-exporter:9115']

  # HTTP endpoint checks
  - job_name: 'blackbox-http'
    metrics_path: /probe
    params:
      module: [http_2xx]
    static_configs:
      - targets:
          - https://api.company.com/health
          - https://www.company.com
          - https://app.company.com/login
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: blackbox-exporter:9115

  # SSL certificate expiry checks
  - job_name: 'blackbox-ssl'
    metrics_path: /probe
    params:
      module: [http_2xx_ssl]
    static_configs:
      - targets:
          - https://api.company.com
          - https://www.company.com
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: blackbox-exporter:9115

  # TCP connectivity checks (databases, etc.)
  - job_name: 'blackbox-tcp'
    metrics_path: /probe
    params:
      module: [tcp_connect]
    static_configs:
      - targets:
          - postgres.internal:5432
          - redis.internal:6379
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: blackbox-exporter:9115

Reload Prometheus config:

# Reload Prometheus (if running in Docker)
docker exec prometheus kill -HUP 1

# Or Kubernetes
kubectl rollout restart deployment/prometheus -n monitoring

Got: Prometheus scraping Blackbox Exporter, metrics visible in Prometheus UI.

If fail: Check Prometheus logs for scrape errors. Verify Blackbox Exporter is reachable.

Step 4: Create Uptime Alerts

Define alerting rules:

# uptime-alerts.yml
groups:
  - name: uptime
    interval: 30s
    rules:
      - alert: EndpointDown
        expr: probe_success == 0
        for: 2m
        labels:
          severity: critical
        annotations:
          summary: "Endpoint {{ $labels.instance }} is down"
          description: "{{ $labels.instance }} has been unreachable for 2 minutes."

      - alert: SSLCertificateExpiringSoon
        expr: (probe_ssl_earliest_cert_expiry - time()) / 86400 < 14
        for: 1h
        labels:
          severity: warning
        annotations:
          summary: "SSL certificate for {{ $labels.instance }} expires in {{ $value | humanizeDuration }}"
          description: "Certificate expires on {{ $labels.instance }}. Renew soon."

      - alert: SSLCertificateExpired
        expr: (probe_ssl_earliest_cert_expiry - time()) < 0
        for: 5m
        labels:
          severity: critical
        annotations:
          summary: "SSL certificate for {{ $labels.instance }} has EXPIRED"
          description: "URGENT: Certificate expired. Service may be inaccessible."

      - alert: SlowResponseTime
        expr: probe_http_duration_seconds > 3
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "Slow response from {{ $labels.instance }}"
          description: "HTTP request took {{ $value }}s (threshold: 3s)."

      - alert: HTTPStatusNot200
        expr: probe_http_status_code != 200
        for: 2m
        labels:
          severity: warning
        annotations:
          summary: "HTTP {{ $labels.instance }} returned {{ $value }}"
          description: "Expected 200, got {{ $value }}."

Load into Prometheus:

# Add to prometheus.yml
rule_files:
  - /etc/prometheus/uptime-alerts.yml

# Reload
docker exec prometheus kill -HUP 1

Got: Alerts fire when endpoints are unreachable or SSL certs expiring.

If fail: Check Prometheus alerts page for rule evaluation errors.

Step 5: Build Uptime Dashboard

Create Grafana dashboard:

{
  "dashboard": {
    "title": "Uptime Monitoring",
    "panels": [
      {
        "title": "Endpoint Availability (7 days)",
# ... (see EXAMPLES.md for complete configuration)

Got: Dashboard showing uptime %, SSL expiry, response times.

If fail: Check Prometheus data source in Grafana, verify metrics are being scraped.

Step 6: Set Up Status Page

Option A: Use Statuspage.io (SaaS):

# Integrate with Statuspage.io API
curl -X POST https://api.statuspage.io/v1/pages/PAGE_ID/incidents \
  -H "Authorization: OAuth YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "incident": {
      "name": "API Degradation",
      "status": "investigating",
      "impact_override": "minor",
      "body": "We are investigating elevated error rates on the API."
    }
  }'

Option B: Self-hosted Cachet:

# docker-compose.yml for Cachet
version: '3'
services:
  cachet:
    image: cachethq/docker:latest
    ports:
# ... (see EXAMPLES.md for complete configuration)

Option C: Custom status page from Prometheus metrics:

<!-- Simple status page (served via Nginx or GitHub Pages) -->
<!DOCTYPE html>
<html>
<head>
  <title>Company Status</title>
  <script src="https://cdn.jsdelivr.net/npm/axios/dist/axios.min.js"></script>
# ... (see EXAMPLES.md for complete configuration)

Got: Public status page shows current service status and incidents.

If fail: Ensure status page URL is reachable by customers, not behind VPN.

Validation

• Blackbox Exporter deployed and accessible
• Prometheus scraping Blackbox metrics
• Uptime checks configured for all critical endpoints
• SSL certificate expiry alerts configured (14-day warning)
• Alerts tested (simulate endpoint down, check alert fires)
• Grafana dashboard shows uptime and SSL expiry
• Status page accessible to customers
• Alert notifications reach on-call engineers

Pitfalls

• Internal-only checks: Blackbox Exporter inside cluster can't detect external DNS/routing issues. Deploy probes in multiple clouds/regions.
• Too frequent scraping: Checking every 10 seconds generates load. 30-60s is usually sufficient.
• No SSL monitoring: Expired certificates are embarrassing and preventable. Always monitor.
• Status page not automated: Manually updating status pages during incidents wastes time. Automate from Prometheus alerts.
• False positives: Single failed check shouldn't alert. Use for: 2m to avoid transient network blips.

Related Skills

• configure-alerting-rules - create alerts for uptime failures
• setup-prometheus-monitoring - Prometheus backend for Blackbox Exporter