Reliability & Infrastructure

    SSL Certificate Expiry Monitoring

    Automate certificate renewal tracking so you never wake up to an expired cert blocking your customers.

    5 min readGuide

    The SSL Expiry Time Bomb

    An expired SSL certificate is one of the most preventable—and embarrassing—outages a SaaS company can experience. Modern browsers block access entirely with scary warning pages. Your users can't reach you, and your brand takes a hit.

    Why Auto-Renewal Isn't Enough

    Let's Encrypt and cloud providers offer auto-renewal, but it fails more often than you'd think.

    DNS Validation Failures

    If your DNS provider has an API outage during renewal, the ACME challenge fails. The cert expires, and you don't know until users complain.

    Permission Changes

    An IAM policy change, API key rotation, or provider configuration update can silently break your auto-renewal. You won't know until 60–90 days later.

    Wildcard Certificate Gaps

    Auto-renewal for wildcard certs often requires different validation than single-domain certs. A new subdomain might not be covered by your wildcard.

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    Setting Up SSL Monitoring

    FourSight's SSL monitoring checks your certificate expiry date, chain validity, and configuration daily. You'll get alerts 30, 14, and 7 days before expiry—plenty of time to fix any auto-renewal issues.

    💡 Monitor SSL on every domain and subdomain you operate. It's common to forget about staging environments, API subdomains, or webhook endpoints that use separate certificates.

    Certificate Chain Validation

    An incomplete certificate chain causes failures on some clients but not others. Mobile browsers are especially strict about chain completeness. FourSight validates the entire chain, not just the leaf certificate.

    SSL Configuration Best Practices

    Beyond expiry, monitor your SSL configuration for security issues: weak cipher suites, outdated TLS versions, and missing HSTS headers. These don't cause outages, but they create security vulnerabilities and can affect your SEO ranking.

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