Quiet OCSP warnings if the cert has a short lifetime (#320)

* Quiet OCSP warnings if the cert has a short lifetime

* Quier differently

* Fix condition

Co-authored-by: Matt Holt <mholt@users.noreply.github.com>

* Oops, had the Lifetime math wrong

---------

Co-authored-by: Matt Holt <mholt@users.noreply.github.com>

certificates.go

@@ -188,6 +188,14 @@ func (cert Certificate) Expired() bool {
 	return time.Now().After(expiresAt(cert.Leaf))
 }
 
+// Lifetime returns the duration of the certificate's validity.
+func (cert Certificate) Lifetime() time.Duration {
+	if cert.Leaf == nil || cert.Leaf.NotAfter.IsZero() {
+		return 0
+	}
+	return expiresAt(cert.Leaf).Sub(cert.Leaf.NotBefore)
+}
+
 // currentlyInRenewalWindow returns true if the current time is within
 // (or after) the renewal window, according to the given start/end
 // dates and the ratio of the renewal window. If true is returned,

ocsp.go

@@ -93,11 +93,16 @@ func stapleOCSP(ctx context.Context, ocspConfig OCSPConfig, storage Storage, cer
 	// then we need to request it from the OCSP responder
 	if ocspResp == nil || len(ocspBytes) == 0 {
 		ocspBytes, ocspResp, ocspErr = getOCSPForCert(ocspConfig, pemBundle)
+		// An error here is not a problem because a certificate
+		// may simply not contain a link to an OCSP server.
 		if ocspErr != nil {
-			// An error here is not a problem because a certificate may simply
-			// not contain a link to an OCSP server. But we should log it anyway.
+			// For short-lived certificates, this is fine and we can ignore
+			// logging because OCSP doesn't make much sense for them anyway.
+			if cert.Lifetime() < 7*24*time.Hour {
+				return nil
+			}
 			// There's nothing else we can do to get OCSP for this certificate,
-			// so we can return here with the error.
+			// so we can return here with the error to warn about it.
 			return fmt.Errorf("no OCSP stapling for %v: %w", cert.Names, ocspErr)
 		}
 		gotNewOCSP = true