====== Runbook: Alerting ======

<WRAP round info>
**Duration:** ~15 minutes \\
**Role:** DevOps, SRE \\
**Prerequisite:** Prometheus, Alertmanager
</WRAP>

Automatic notifications for Gateway problems.

----

===== Workflow =====

<mermaid>
flowchart TD
    A[Start] --> B[Define alert rules]
    B --> C[Configure Alertmanager]
    C --> D[Set up receivers]
    D --> E[Trigger test alert]
    E --> F{Notified?}
    F -->|Yes| G[Done]
    F -->|No| H[Check config]

    style G fill:#e8f5e9
    style H fill:#ffebee
</mermaid>

----

===== 1. Alert Rules (Prometheus) =====

**/etc/prometheus/rules/gateway-alerts.yml:**

<code yaml>
groups:
  - name: data-gateway
    interval: 30s
    rules:
      # Gateway not reachable
      - alert: GatewayDown
        expr: up{job="data-gateway"} == 0
        for: 1m
        labels:
          severity: critical
        annotations:
          summary: "Data Gateway is not reachable"
          description: "{{ $labels.instance }} has been unreachable for 1 minute."

      # High error rate
      - alert: GatewayHighErrorRate
        expr: |
          sum(rate(http_requests_total{job="data-gateway",status=~"5.."}[5m]))
          /
          sum(rate(http_requests_total{job="data-gateway"}[5m]))
          > 0.05
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High error rate in Gateway"
          description: "Error rate is {{ $value | humanizePercentage }} (> 5%)."

      # Slow response times
      - alert: GatewaySlowResponses
        expr: |
          histogram_quantile(0.95,
            sum(rate(http_request_duration_seconds_bucket{job="data-gateway"}[5m])) by (le)
          ) > 2
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "Gateway responding slowly"
          description: "P95 response time is {{ $value | humanizeDuration }}."

      # High memory usage
      - alert: GatewayHighMemory
        expr: |
          process_resident_memory_bytes{job="data-gateway"}
          / 1024 / 1024 > 450
        for: 10m
        labels:
          severity: warning
        annotations:
          summary: "Gateway using high memory"
          description: "Memory usage is {{ $value | humanize }}MB."

      # Certificate expiring soon
      - alert: GatewayCertExpiringSoon
        expr: |
          (probe_ssl_earliest_cert_expiry{job="gateway-tls"} - time())
          / 86400 < 14
        for: 1h
        labels:
          severity: warning
        annotations:
          summary: "Gateway TLS certificate expiring soon"
          description: "Certificate expires in {{ $value | humanize }} days."
</code>

----

===== 2. Update Prometheus Config =====

**/etc/prometheus/prometheus.yml:**

<code yaml>
rule_files:
  - "rules/*.yml"

alerting:
  alertmanagers:
    - static_configs:
        - targets:
            - alertmanager:9093
</code>

<code bash>
# Reload Prometheus
curl -X POST http://localhost:9090/-/reload
</code>

----

===== 3. Alertmanager Configuration =====

**/etc/alertmanager/alertmanager.yml:**

<code yaml>
global:
  resolve_timeout: 5m
  smtp_smarthost: 'smtp.example.com:587'
  smtp_from: 'alertmanager@example.com'
  smtp_auth_username: 'alertmanager@example.com'
  smtp_auth_password: 'secret'

route:
  group_by: ['alertname', 'severity']
  group_wait: 30s
  group_interval: 5m
  repeat_interval: 4h
  receiver: 'default'
  routes:
    # Critical alerts immediately
    - match:
        severity: critical
      receiver: 'critical'
      group_wait: 10s
      repeat_interval: 1h

receivers:
  - name: 'default'
    email_configs:
      - to: 'ops@example.com'
        send_resolved: true

  - name: 'critical'
    email_configs:
      - to: 'oncall@example.com'
        send_resolved: true
    slack_configs:
      - api_url: 'https://hooks.slack.com/services/XXX/YYY/ZZZ'
        channel: '#alerts-critical'
        send_resolved: true
        title: '{{ .Status | toUpper }}: {{ .CommonAnnotations.summary }}'
        text: '{{ .CommonAnnotations.description }}'

inhibit_rules:
  - source_match:
      severity: 'critical'
    target_match:
      severity: 'warning'
    equal: ['alertname', 'instance']
</code>

----

===== 4. Slack Integration =====

<code yaml>
# Slack section only
receivers:
  - name: 'slack-alerts'
    slack_configs:
      - api_url: 'https://hooks.slack.com/services/XXX/YYY/ZZZ'
        channel: '#gateway-alerts'
        send_resolved: true
        title: '{{ if eq .Status "firing" }}ALERT{{ else }}RESOLVED{{ end }} {{ .CommonAnnotations.summary }}'
        text: |
          *Alert:* {{ .CommonLabels.alertname }}
          *Severity:* {{ .CommonLabels.severity }}
          *Description:* {{ .CommonAnnotations.description }}
          *Instance:* {{ .CommonLabels.instance }}
</code>

----

===== 5. Microsoft Teams =====

<code yaml>
# Via Prometheus MS Teams Webhook
receivers:
  - name: 'teams-alerts'
    webhook_configs:
      - url: 'http://prometheus-msteams:2000/gateway'
        send_resolved: true
</code>

----

===== 6. Test Alert =====

<code bash>
# Check alert rules
curl http://localhost:9090/api/v1/rules | jq '.data.groups[].rules[] | {alert: .name, state: .state}'

# Active alerts
curl http://localhost:9090/api/v1/alerts | jq '.data.alerts[]'

# Alertmanager status
curl http://localhost:9093/api/v2/status | jq

# Send test alert
curl -X POST http://localhost:9093/api/v2/alerts \
  -H "Content-Type: application/json" \
  -d '[{
    "labels": {"alertname": "TestAlert", "severity": "warning"},
    "annotations": {"summary": "Test Alert", "description": "This is a test."}
  }]'
</code>

----

===== 7. Checklist =====

| # | Check | Done |
|---|-------|------|
| 1 | Alert rules created | [ ] |
| 2 | Prometheus config updated | [ ] |
| 3 | Alertmanager configured | [ ] |
| 4 | Receiver tested (E-Mail/Slack) | [ ] |
| 5 | Test alert received | [ ] |

----

===== Troubleshooting =====

| Problem | Cause | Solution |
|---------|-------|----------|
| ''No alerts'' | Rule syntax wrong | ''promtool check rules rules.yml'' |
| ''Alert not firing'' | Condition not met | Test query manually |
| ''No notification'' | Receiver wrong | Check Alertmanager logs |
| ''Duplicate alerts'' | Wrong grouping | Adjust ''group_by'' |

----

===== Recommended Thresholds =====

| Alert | Threshold | Duration |
|-------|-----------|----------|
| GatewayDown | up == 0 | 1m |
| HighErrorRate | > 5% | 5m |
| SlowResponses | p95 > 2s | 5m |
| HighMemory | > 450MB | 10m |
| CertExpiring | < 14 days | 1h |

----

===== Related Runbooks =====

  * [[.:prometheus|Prometheus]] - Collect metrics
  * [[.:grafana-dashboard|Grafana]] - Visualization
  * [[..:sicherheit:tls-einrichten|Set Up TLS]] - Certificate alerting

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<< [[.:grafana-dashboard|<- Grafana Dashboard]] | [[..:start|-> Operator Overview]] >>

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//Wolfgang van der Stille @ EMSR DATA d.o.o. - Data Gateway Professional//

{{tag>operator runbook alerting prometheus alertmanager}}