SSL/TLS Management

Manage certificates and secure communications across web servers, Kubernetes clusters, and internal services.

Prerequisites

• Domain name with DNS control for public certificates
• Root/sudo access on web servers
• certbot installed for Let's Encrypt
• openssl CLI available (installed by default on most Linux distros)
• Kubernetes cluster with Helm for cert-manager deployment
• Understanding of X.509 certificate chain of trust

Let's Encrypt with Certbot

Installation and Certificate Issuance

# Install certbot (Ubuntu/Debian)
apt update && apt install -y certbot python3-certbot-nginx

# Obtain certificate for nginx (interactive)
certbot --nginx -d example.com -d www.example.com

# Non-interactive mode for automation
certbot certonly --nginx \
  -d example.com \
  -d www.example.com \
  --non-interactive \
  --agree-tos \
  --email admin@example.com

# Standalone mode (when no web server is running)
certbot certonly --standalone \
  -d example.com \
  --preferred-challenges http

# DNS challenge (for wildcard certs)
certbot certonly --manual \
  --preferred-challenges dns \
  -d "*.example.com" \
  -d example.com

# Using DNS plugin for automation (Cloudflare example)
pip install certbot-dns-cloudflare
cat > /etc/letsencrypt/cloudflare.ini << 'EOF'
dns_cloudflare_api_token = YOUR_CLOUDFLARE_API_TOKEN
EOF
chmod 600 /etc/letsencrypt/cloudflare.ini

certbot certonly --dns-cloudflare \
  --dns-cloudflare-credentials /etc/letsencrypt/cloudflare.ini \
  -d "*.example.com" \
  -d example.com

Renewal Automation

# Test renewal
certbot renew --dry-run

# Systemd timer (preferred over cron)
cat > /etc/systemd/system/certbot-renewal.service << 'EOF'
[Unit]
Description=Certbot certificate renewal
After=network-online.target

[Service]
Type=oneshot
ExecStart=/usr/bin/certbot renew --quiet --deploy-hook "systemctl reload nginx"
EOF

cat > /etc/systemd/system/certbot-renewal.timer << 'EOF'
[Unit]
Description=Run certbot renewal twice daily

[Timer]
OnCalendar=*-*-* 00,12:00:00
RandomizedDelaySec=3600
Persistent=true

[Install]
WantedBy=timers.target
EOF

systemctl enable --now certbot-renewal.timer

# Verify timer is active
systemctl list-timers certbot-renewal.timer

# Renewal hooks for post-renewal actions
mkdir -p /etc/letsencrypt/renewal-hooks/deploy
cat > /etc/letsencrypt/renewal-hooks/deploy/reload-services.sh << 'HOOK'
#!/bin/bash
systemctl reload nginx
# Also reload other services using the cert
systemctl reload haproxy 2>/dev/null || true
HOOK
chmod +x /etc/letsencrypt/renewal-hooks/deploy/reload-services.sh

cert-manager for Kubernetes

Installation

# Install with Helm
helm repo add jetstack https://charts.jetstack.io
helm repo update

helm install cert-manager jetstack/cert-manager \
  --namespace cert-manager \
  --create-namespace \
  --version v1.14.0 \
  --set installCRDs=true \
  --set prometheus.enabled=true

# Verify installation
kubectl get pods -n cert-manager
kubectl get crds | grep cert-manager

ClusterIssuer Configurations

# letsencrypt-staging (use for testing first)
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: letsencrypt-staging
spec:
  acme:
    server: https://acme-staging-v02.api.letsencrypt.org/directory
    email: admin@example.com
    privateKeySecretRef:
      name: letsencrypt-staging
    solvers:
      - http01:
          ingress:
            class: nginx
---
# letsencrypt-prod
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: letsencrypt-prod
spec:
  acme:
    server: https://acme-v02.api.letsencrypt.org/directory
    email: admin@example.com
    privateKeySecretRef:
      name: letsencrypt-prod
    solvers:
      - http01:
          ingress:
            class: nginx
---
# DNS challenge solver (for wildcard certs with Cloudflare)
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: letsencrypt-prod-dns
spec:
  acme:
    server: https://acme-v02.api.letsencrypt.org/directory
    email: admin@example.com
    privateKeySecretRef:
      name: letsencrypt-prod-dns
    solvers:
      - dns01:
          cloudflare:
            apiTokenSecretRef:
              name: cloudflare-api-token
              key: api-token
---
# Self-signed CA issuer for internal services
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: selfsigned-ca
spec:
  selfSigned: {}

Certificate Resources

# Public-facing certificate

…