βΆWhat's cert-manager and why not just buy certificates?
Cert-manager automates renewal so you never forget. Bought certs expire in 1-3 years; you must manually renew. Let's Encrypt certs expire in 90 days but auto-renew. Cert-manager handles both. On Kubernetes, cert-manager integrates with Ingress (automagically sets TLS) and integrates with Let's Encrypt ACME.
βΆIs Let's Encrypt free really free?
Yes, fully free (donated by EFF, Mozilla, etc.). Rate-limited: 50 certificates per domain per week. Perfect for most teams. Wildcard certs also free. Downside: no phone support, basic validation only. Enterprise CAs (DigiCert, Entrust) cost $200-1000/year but offer phone support and higher validation.
βΆHow often does cert-manager renew certificates?
Default: renew 30 days before expiration. Let's Encrypt certs expire 90 days after issue, so renewal happens at day ~60. You can customize this (earlier renewal for peace of mind). Failed renewals auto-retry. If manual intervention needed, cert-manager sends alerts.
βΆCan cert-manager manage non-Kubernetes certificates?
Not natively. Cert-manager runs as Kubernetes operator; it manages certs as K8s resources. For non-K8s apps, use cert-manager to generate cert (stored as Secret), then manually copy to app server. Or use Vault (alternative CA) for broader infrastructure.
βΆWhat's the difference between HTTP-01 and DNS-01 challenges?
HTTP-01: ACME server validates by accessing .well-known/acme-challenge/{token} on your domain. Requires public HTTP access. Faster, simpler. DNS-01: ACME server checks DNS TXT record for token. Requires DNS API access. Enables wildcard certs, works behind firewalls. Pick based on your setup; most teams use HTTP-01.
βΆHow do I debug a failed certificate renewal?
Check cert-manager logs: kubectl logs -n cert-manager deploy/cert-manager. Look for ACME challenge failures. Common: DNS misconfiguration, firewall blocking HTTP-01, rate limits hit. Inspect Certificate resource: kubectl describe cert <name>. View Issuer status. Most failures = network connectivity, not cert-manager bugs.
βΆWhat salary jump for cert-manager expertise?
Platform engineer ($100-130k) β cert-manager + PKI specialist ($130-160k). Rare skill: only 30% of K8s teams automate certs fully. Managing certs for 500+ microservices = premium compensation. Senior (architecture): $160-200k.