We use a daily Ruby script that puts data into InfluxDB and we use Grafana to warn us if a certificate is close to expire: tcp_client = TCPSocket.new(domai

We use a daily Ruby script that puts data into InfluxDB and we use Grafana to warn us if a certificate is close to expire: tcp_client = TCPSocket.new(domain, 443) ssl_client = OpenSSL::SSL::SSLSocket.new(tcp_client) ssl_client.hostname = domain ssl_client.connect cert = OpenSSL::X509::Certificate.new(ssl_client.peer_cert) ssl_client.sysclose tcp_client.close certprops = OpenSSL::X509::Name.new(cert.issuer).to_a issuer = certprops.select { |name, data, type| name == "O" }.first[1] results = { valid_on: cert.not_before.utc, valid_until: cert.not_after.utc, issuer: issuer, days_left: (cert.not_after.utc - Time.now.utc).to_i / (24 * 60 * 60), }