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

<WRAP round info>
**Složenost:** Visoka \\
**Trajanje:** 2-3 sata postavljanja \\
**Preduvjet:** Kubernetes 1.25+, Helm
</WRAP>

Automatsko upravljanje certifikatima u Kubernetesu s cert-managerom i vlastitom PKI.

----

===== Arhitektura =====

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

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

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

    subgraph EXTERNAL["VANJSKI CA"]
        CA[Interni CA]
        V[Vault PKI]
        LE[Let's Encrypt]
    end

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

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

----

===== Instalacija =====

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

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

# Provjera instalacije
kubectl get pods -n cert-manager
</code>

----

===== Tipovi Issuera =====

| Tip Issuera | Primjena | PQ podrška |
|-------------|----------|------------|
| SelfSigned | Testiranje, Bootstrapping | Ne |
| CA | Interna PKI | **Da (s WvdS)** |
| Vault | HashiCorp Vault PKI | Djelomično |
| ACME | Let's Encrypt, javni CA-ovi | Ne |
| Venafi | Enterprise PKI | Djelomično |

----

===== ClusterIssuer s vlastitim CA =====

==== Korak 1: Stvaranje CA Secreta ====

<code bash>
# CA certifikat i ključ kao Secret
kubectl create secret tls ca-key-pair \
    --cert=intermediate-ca.pem \
    --key=intermediate-ca.key \
    --namespace cert-manager
</code>

Ili kao 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>

==== Korak 2: Definiranje ClusterIssuera ====

<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

# Provjera statusa
kubectl get clusterissuer internal-ca-issuer
</code>

----

===== Certificate resurs =====

<code yaml>
# certificate.yaml
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: app-tls
  namespace: production
spec:
  # Secret koji se stvara
  secretName: app-tls-secret

  # Trajanje valjanosti
  duration: 2160h    # 90 dana
  renewBefore: 360h  # 15 dana prije isteka obnoviti

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

  # Konfiguracija ključa
  privateKey:
    algorithm: ECDSA
    size: 384
    rotationPolicy: Always

  # Namjena
  usages:
    - server auth
    - client auth

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

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

<code bash>
kubectl apply -f certificate.yaml

# Provjera statusa
kubectl get certificate -n production
kubectl describe certificate app-tls -n production

# Prikaz Secreta
kubectl get secret app-tls-secret -n production -o yaml
</code>

----

===== Ingress anotacija (automatski) =====

<code yaml>
# ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: app-ingress
  namespace: production
  annotations:
    # cert-manager automatski stvara certifikat
    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 integracija =====

<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 konfiguracija:**

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

# Generiranje Root CA (ili import)
vault write pki/root/generate/internal \
    common_name="Internal Root CA" \
    ttl=87600h

# Uloga za 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>

----

===== Nadzor =====

==== Prometheus metrike ====

<code yaml>
# ServiceMonitor za 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>

**Važne metrike:**

| Metrika | Opis | Prag za alert |
|---------|------|---------------|
| ''certmanager_certificate_expiration_timestamp_seconds'' | Vrijeme isteka | < 7 dana |
| ''certmanager_certificate_ready_status'' | Ready status | != 1 |
| ''certmanager_certificate_renewal_timestamp_seconds'' | Posljednja obnova | - |

==== Alert pravila ====

<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: "Certifikat {{ $labels.name }} istječe za < 7 dana"

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

----

===== Rješavanje problema =====

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

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

# Logovi cert-managera
kubectl logs -n cert-manager -l app=cert-manager -f

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

**Česti problemi:**

| Problem | Uzrok | Rješenje |
|---------|-------|----------|
| ''Issuer not found'' | ClusterIssuer vs. Issuer | Provjeriti Kind |
| ''Secret not found'' | CA Secret nije stvoren | Stvoriti Secret |
| ''Failed to generate CSR'' | Algoritam ključa | Provjeriti Algorithm/Size |
| ''Challenge failed'' | ACME problem | Provjeriti DNS/HTTP Challenge |

----

===== Post-Quantum s vlastitim CA =====

<WRAP round tip>
**PQ certifikati s cert-managerom:**

Cert-manager sam ne podržava PQ algoritme, ali možete koristiti PQ-sposobni CA i ručno stvarati certifikate.
</WRAP>

<code csharp>
// Stvaranje Kubernetes Secreta s PQ certifikatom
using var intermediate = new X509Certificate2("intermediate.pfx", "password");

// Učitavanje CSR iz Kubernetesa
var csr = CertificateRequest.LoadSigningRequest(csrBytes, HashAlgorithmName.SHA384);

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

// Spremanje kao Kubernetes Secret
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>

----

===== Kontrolna lista =====

| # | Točka provjere | Gotovo |
|---|----------------|--------|
| 1 | cert-manager instaliran | ☐ |
| 2 | ClusterIssuer konfiguriran | ☐ |
| 3 | CA Secret stvoren | ☐ |
| 4 | Test-Certificate funkcionira | ☐ |
| 5 | Prometheus nadzor aktivan | ☐ |
| 6 | Alerti konfigurirani | ☐ |

----

===== Povezana dokumentacija =====

  * [[.:acme-integration|ACME integracija]] - Za javne certifikate
  * [[..:cloud:hashicorp-vault|HashiCorp Vault]] - Vault PKI backend
  * [[hr:int:pqcrypt:szenarien:tls:start|TLS/mTLS]] - Korištenje certifikata

----

<< [[.:cicd-code-signing|<- CI/CD potpisivanje koda]] | [[.:scheduled-renewal|-> Zakazana obnova]] >>

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

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