Show HN: X509-certificate-exporter – Prometheus exporter for TLS cert expiration

Certificates expire silently. Kubernetes won't warn you, and most teams find out when something breaks. This exporter watches PEM files, kubeconfigs, Kubernetes TLS secrets, and PKCS#12 bundles, and exposes expiration as Prometheus metrics you can alert on. It works standalone too, no Kubernetes required. A Grafana dashboard is included. The new release is a major rewrite, built from experience running this across a large number of production clusters. The main pain point it addresses: at scale, with thousands of certificates, the exporter was putting too much pressure on the Kubernetes API. We also put a lot of care into supply chain security this time around.