openova/platform/cert-manager

cert-manager

TLS certificate automation. Per-host-cluster infrastructure (see docs/ARCHITECTURE.md §3.3) — runs on every host cluster a Sovereign owns.

Status: Accepted | Updated: 2026-04-27

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Overview

cert-manager provides automated TLS certificate management using Let's Encrypt with automatic renewal and Kubernetes-native integration.

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Architecture

flowchart TB
    subgraph CM["cert-manager"]
        Controller[Controller]
        Webhook[Webhook]
        CAInjector[CA Injector]
    end

    subgraph Issuers["Issuers"]
        LE[Let's Encrypt]
        CA[Internal CA]
    end

    subgraph Resources["K8s Resources"]
        Cert[Certificate]
        Secret[TLS Secret]
        Ingress[Gateway/Ingress]
    end

    Controller --> LE
    Controller --> CA
    Cert --> Controller
    Controller --> Secret
    Secret --> Ingress

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Challenge Types

Challenge	Use Case	DNS Provider
HTTP-01	Public endpoints	Not required
DNS-01	Wildcards, internal	Cloudflare, Route53, etc.

Recommended: DNS-01 for wildcard certificates

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Configuration

ClusterIssuer (Let's Encrypt)

apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: letsencrypt-prod
spec:
  acme:
    server: https://acme-v02.api.letsencrypt.org/directory
    email: admin@<domain>
    privateKeySecretRef:
      name: letsencrypt-prod-key
    solvers:
      - dns01:
          cloudflare:
            apiTokenSecretRef:
              name: cloudflare-api-token
              key: api-token

Certificate

apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: wildcard-cert
  namespace: cilium-gateway
spec:
  secretName: wildcard-tls
  issuerRef:
    name: letsencrypt-prod
    kind: ClusterIssuer
  dnsNames:
    - "*.<domain>"
    - "<domain>"

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Gateway API Integration

cert-manager integrates with Cilium Gateway API:

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: main-gateway
  namespace: cilium-gateway
spec:
  gatewayClassName: cilium
  listeners:
    - name: https
      protocol: HTTPS
      port: 443
      tls:
        mode: Terminate
        certificateRefs:
          - name: wildcard-tls

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Renewal

Setting	Value
Renewal window	30 days before expiry
Check interval	24 hours
Retry interval	1 hour on failure

cert-manager automatically renews certificates before expiration.

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Monitoring

Metric	Description
certmanager_certificate_expiration_timestamp_seconds	Certificate expiry time
certmanager_certificate_ready_status	Certificate readiness
certmanager_http_acme_client_request_count	ACME requests

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