====== Kubernetes Cert-Manager ======

<WRAP round info>
**Komplexität:** Hoch \\
**Dauer:** 2-3 Stunden Setup \\
**Voraussetzung:** Kubernetes 1.25+, Helm
</WRAP>

Automatische Zertifikatsverwaltung in Kubernetes mit cert-manager und eigener PKI.

----

===== Architektur =====

<mermaid>
flowchart TB
    subgraph K8S["☸️ KUBERNETES CLUSTER"]
        subgraph CM["cert-manager"]
            I[Issuer/ClusterIssuer]
            C[Certificate]
            CR[CertificateRequest]
        end

        subgraph APP["Anwendung"]
            P[Pod]
            S[Secret]
            ING[Ingress]
        end

        C --> CR --> I
        I --> S
        S --> P
        S --> ING
    end

    subgraph EXTERNAL["🔐 EXTERNE CA"]
        CA[Internal CA]
        V[Vault PKI]
        LE[Let's Encrypt]
    end

    I --> CA
    I --> V
    I --> LE

    style CM fill:#e3f2fd
    style I fill:#fff3e0
</mermaid>

----

===== Installation =====

<code bash>
# Helm Repository hinzufügen
helm repo add jetstack https://charts.jetstack.io
helm repo update

# cert-manager installieren
helm install cert-manager jetstack/cert-manager \
    --namespace cert-manager \
    --create-namespace \
    --set installCRDs=true \
    --set prometheus.enabled=true

# Installation prüfen
kubectl get pods -n cert-manager
</code>

----

===== Issuer-Typen =====

| Issuer-Typ | Use Case | PQ-Support |
|------------|----------|------------|
| SelfSigned | Testing, Bootstrapping | Nein |
| CA | Interne PKI | **Ja (mit WvdS)** |
| Vault | HashiCorp Vault PKI | Teilweise |
| ACME | Let's Encrypt, öffentliche CAs | Nein |
| Venafi | Enterprise PKI | Teilweise |

----

===== ClusterIssuer mit eigener CA =====

==== Schritt 1: CA-Secret erstellen ====

<code bash>
# CA-Zertifikat und Key als Secret
kubectl create secret tls ca-key-pair \
    --cert=intermediate-ca.pem \
    --key=intermediate-ca.key \
    --namespace cert-manager
</code>

Oder als YAML:

<code yaml>
# ca-secret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: ca-key-pair
  namespace: cert-manager
type: kubernetes.io/tls
data:
  tls.crt: <base64-encoded-ca-cert>
  tls.key: <base64-encoded-ca-key>
</code>

==== Schritt 2: ClusterIssuer definieren ====

<code yaml>
# cluster-issuer.yaml
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: internal-ca-issuer
spec:
  ca:
    secretName: ca-key-pair
</code>

<code bash>
kubectl apply -f cluster-issuer.yaml

# Status prüfen
kubectl get clusterissuer internal-ca-issuer
</code>

----

===== Certificate-Ressource =====

<code yaml>
# certificate.yaml
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: app-tls
  namespace: production
spec:
  # Secret, das erstellt wird
  secretName: app-tls-secret

  # Gültigkeitsdauer
  duration: 2160h    # 90 Tage
  renewBefore: 360h  # 15 Tage vor Ablauf erneuern

  # Subject
  subject:
    organizations:
      - EMSR DATA
  commonName: app.example.com

  # Schlüssel-Konfiguration
  privateKey:
    algorithm: ECDSA
    size: 384
    rotationPolicy: Always

  # Verwendungszweck
  usages:
    - server auth
    - client auth

  # DNS/IP SANs
  dnsNames:
    - app.example.com
    - app.production.svc.cluster.local
  ipAddresses:
    - 10.0.0.100

  # Issuer-Referenz
  issuerRef:
    name: internal-ca-issuer
    kind: ClusterIssuer
</code>

<code bash>
kubectl apply -f certificate.yaml

# Status prüfen
kubectl get certificate -n production
kubectl describe certificate app-tls -n production

# Secret anzeigen
kubectl get secret app-tls-secret -n production -o yaml
</code>

----

===== Ingress-Annotation (automatisch) =====

<code yaml>
# ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: app-ingress
  namespace: production
  annotations:
    # cert-manager erstellt Zertifikat automatisch
    cert-manager.io/cluster-issuer: "internal-ca-issuer"
spec:
  tls:
    - hosts:
        - app.example.com
      secretName: app-ingress-tls
  rules:
    - host: app.example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: app-service
                port:
                  number: 80
</code>

----

===== Vault PKI Integration =====

<code yaml>
# vault-issuer.yaml
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: vault-issuer
spec:
  vault:
    server: https://vault.example.com
    path: pki/sign/server-role
    caBundle: <base64-encoded-vault-ca>
    auth:
      kubernetes:
        role: cert-manager
        mountPath: /v1/auth/kubernetes
        secretRef:
          name: vault-token
          key: token
</code>

**Vault-Konfiguration:**

<code bash>
# PKI Engine aktivieren
vault secrets enable pki
vault secrets tune -max-lease-ttl=87600h pki

# Root-CA generieren (oder importieren)
vault write pki/root/generate/internal \
    common_name="Internal Root CA" \
    ttl=87600h

# Rolle für cert-manager
vault write pki/roles/server-role \
    allowed_domains="example.com,svc.cluster.local" \
    allow_subdomains=true \
    max_ttl=720h

# Kubernetes Auth
vault auth enable kubernetes
vault write auth/kubernetes/config \
    kubernetes_host="https://kubernetes.default.svc"
</code>

----

===== Monitoring =====

==== Prometheus Metrics ====

<code yaml>
# ServiceMonitor für cert-manager
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: cert-manager
  namespace: monitoring
spec:
  selector:
    matchLabels:
      app.kubernetes.io/name: cert-manager
  endpoints:
    - port: http-metrics
</code>

**Wichtige Metriken:**

| Metrik | Beschreibung | Alert-Schwelle |
|--------|--------------|----------------|
| ''certmanager_certificate_expiration_timestamp_seconds'' | Ablaufzeit | < 7 Tage |
| ''certmanager_certificate_ready_status'' | Ready-Status | != 1 |
| ''certmanager_certificate_renewal_timestamp_seconds'' | Letzte Erneuerung | - |

==== Alert-Rules ====

<code yaml>
# PrometheusRule
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: cert-manager-alerts
  namespace: monitoring
spec:
  groups:
    - name: cert-manager
      rules:
        - alert: CertificateExpiringSoon
          expr: |
            certmanager_certificate_expiration_timestamp_seconds - time() < 604800
          for: 1h
          labels:
            severity: warning
          annotations:
            summary: "Zertifikat {{ $labels.name }} läuft in < 7 Tagen ab"

        - alert: CertificateNotReady
          expr: |
            certmanager_certificate_ready_status != 1
          for: 10m
          labels:
            severity: critical
          annotations:
            summary: "Zertifikat {{ $labels.name }} nicht bereit"
</code>

----

===== Troubleshooting =====

<code bash>
# Certificate-Status
kubectl get certificate -A
kubectl describe certificate <name> -n <namespace>

# CertificateRequest prüfen
kubectl get certificaterequest -A
kubectl describe certificaterequest <name>

# cert-manager Logs
kubectl logs -n cert-manager -l app=cert-manager -f

# Events
kubectl get events -n cert-manager --sort-by='.lastTimestamp'
</code>

**Häufige Probleme:**

| Problem | Ursache | Lösung |
|---------|---------|--------|
| ''Issuer not found'' | ClusterIssuer vs. Issuer | Kind prüfen |
| ''Secret not found'' | CA-Secret nicht erstellt | Secret anlegen |
| ''Failed to generate CSR'' | Key-Algorithmus | Algorithm/Size prüfen |
| ''Challenge failed'' | ACME-Problem | DNS/HTTP Challenge prüfen |

----

===== Post-Quantum mit eigener CA =====

<WRAP round tip>
**PQ-Zertifikate mit cert-manager:**

Cert-manager selbst unterstützt keine PQ-Algorithmen, aber Sie können eine PQ-fähige CA verwenden und die Zertifikate manuell erstellen.
</WRAP>

<code csharp>
// Kubernetes Secret mit PQ-Zertifikat erstellen
using var intermediate = new X509Certificate2("intermediate.pfx", "password");

// CSR aus Kubernetes laden
var csr = CertificateRequest.LoadSigningRequest(csrBytes, HashAlgorithmName.SHA384);

// PQ-Hybrid-Zertifikat ausstellen
var cert = csr.Create(
    intermediate,
    DateTimeOffset.UtcNow,
    DateTimeOffset.UtcNow.AddDays(90),
    Guid.NewGuid().ToByteArray(),
    CryptoMode.Hybrid);

// Als Kubernetes Secret speichern
var secret = new V1Secret
{
    Metadata = new V1ObjectMeta { Name = "pq-tls-secret" },
    Type = "kubernetes.io/tls",
    Data = new Dictionary<string, byte[]>
    {
        ["tls.crt"] = Encoding.UTF8.GetBytes(cert.ExportCertificatePem()),
        ["tls.key"] = Encoding.UTF8.GetBytes(cert.GetECDsaPrivateKey().ExportPkcs8PrivateKeyPem())
    }
};
</code>

----

===== Checkliste =====

| # | Prüfpunkt | ✓ |
|---|-----------|---|
| 1 | cert-manager installiert | ☐ |
| 2 | ClusterIssuer konfiguriert | ☐ |
| 3 | CA-Secret erstellt | ☐ |
| 4 | Test-Certificate funktioniert | ☐ |
| 5 | Prometheus Monitoring aktiv | ☐ |
| 6 | Alerts konfiguriert | ☐ |

----

===== Verwandte Dokumentation =====

  * [[.:acme-integration|ACME Integration]] – Für öffentliche Zertifikate
  * [[..:cloud:hashicorp-vault|HashiCorp Vault]] – Vault PKI Backend
  * [[de:int:pqcrypt:szenarien:tls:start|TLS/mTLS]] – Zertifikat-Verwendung

----

<< [[.:cicd-code-signing|← CI/CD Code-Signing]] | [[.:scheduled-renewal|→ Scheduled Renewal]] >>

----
//Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional//

{{tag>kubernetes cert-manager helm vault automatisierung operator}}