Simplify timing mechanism for checking renewals

config/letsencrypt/letsencrypt.go

@@ -7,7 +7,6 @@ import (
 	"encoding/json"
 	"errors"
 	"io/ioutil"
-	"log"
 	"net/http"
 	"os"
 	"strings"
@@ -40,7 +39,8 @@ func Activate(configs []server.Config) ([]server.Config, error) {
 			configs = autoConfigure(&configs[i], configs)
 		}
 	}
-	// Handle cert renewal on Startup
+
+	// First renew any existing certificates that need it
 	processCertificateRenewal(configs)
 
 	// Group configs by LE email address; this will help us
@@ -77,7 +77,7 @@ func Activate(configs []server.Config) ([]server.Config, error) {
 		}
 	}
 
-	go renewalFunc(configs)
+	go keepCertificatesRenewed(configs)
 
 	return configs, nil
 }
@@ -284,141 +284,6 @@ func redirPlaintextHost(cfg server.Config) server.Config {
 	}
 }
 
-func renewalFunc(configs []server.Config) {
-	nextRun, err := processCertificateRenewal(configs)
-	if err != nil {
-		log.Printf("[ERROR] Could not start renewal routine. %v", err)
-		return
-	}
-
-	for {
-		timer := time.NewTimer(time.Duration(nextRun) * time.Hour)
-		<-timer.C
-		nextRun, err = processCertificateRenewal(configs)
-		if err != nil {
-			log.Printf("[ERROR] Renewal routing stopped. %v", err)
-			return
-		}
-	}
-}
-
-// checkCertificateRenewal loops through all configured
-// sites and looks for certificates to renew. Nothing is mutated
-// through this function. The changes happen directly on disk.
-func processCertificateRenewal(configs []server.Config) (int, error) {
-	log.Print("[INFO] Processing certificate renewals...")
-	// Check if we should run. If not, get out of here.
-	next, err := getNextRenewalShedule()
-	if err != nil {
-		return 0, err
-	}
-
-	if next > 0 {
-		return next, nil
-	}
-
-	// We are executing. Write the current timestamp into the file.
-	err = ioutil.WriteFile(storage.RenewTimerFile(), []byte(time.Now().UTC().Format(time.RFC3339)), 0600)
-	if err != nil {
-		return 0, err
-	}
-	next = renewTimer
-
-	for _, cfg := range configs {
-		// Check if this entry is TLS enabled and managed by LE
-		if !cfg.TLS.Enabled || !existingCertAndKey(cfg.Host) {
-			continue
-		}
-
-		// Read the certificate and get the NotAfter time.
-		certBytes, err := ioutil.ReadFile(storage.SiteCertFile(cfg.Host))
-		if err != nil {
-			return 0, err
-		}
-		expTime, err := acme.GetPEMCertExpiration(certBytes)
-		if err != nil {
-			return 0, err
-		}
-
-		// The time returned from the certificate is always in UTC.
-		// So calculate the time left with local time as UTC.
-		// Directly convert it to days for the following checks.
-		daysLeft := int(expTime.Sub(time.Now().UTC()).Hours() / 24)
-
-		// Renew on two or less days remaining.
-		if daysLeft <= 2 {
-			log.Printf("[WARN] There are %d days left on the certificate of %s. Trying to renew now.", daysLeft, cfg.Host)
-			client, err := newClient(getEmail(cfg))
-			if err != nil {
-				return 0, err
-			}
-
-			// Read metadata
-			metaBytes, err := ioutil.ReadFile(storage.SiteMetaFile(cfg.Host))
-			if err != nil {
-				return 0, err
-			}
-
-			privBytes, err := ioutil.ReadFile(storage.SiteKeyFile(cfg.Host))
-			if err != nil {
-				return 0, err
-			}
-
-			var certMeta acme.CertificateResource
-			err = json.Unmarshal(metaBytes, &certMeta)
-			certMeta.Certificate = certBytes
-			certMeta.PrivateKey = privBytes
-
-			// Renew certificate.
-			// TODO: revokeOld should be an option in the caddyfile
-			newCertMeta, err := client.RenewCertificate(certMeta, true)
-			if err != nil {
-				return 0, err
-			}
-
-			saveCertsAndKeys([]acme.CertificateResource{newCertMeta})
-		}
-
-		// Warn on 14 days remaining
-		if daysLeft <= 14 {
-			log.Printf("[WARN] There are %d days left on the certificate of %s. Will renew on two days left.\n", daysLeft, cfg.Host)
-		}
-	}
-
-	return next, nil
-}
-
-// getNextRenewalShedule calculates the offset in hours the renew process should
-// run from the current time. If the file the time is in does not exists, the
-// function returns zero to trigger a renew asap.
-func getNextRenewalShedule() (int, error) {
-
-	// Check if the file exists. If it does not, return 0 to indicate immediate processing.
-	if _, err := os.Stat(storage.RenewTimerFile()); os.IsNotExist(err) {
-		return 0, nil
-	}
-
-	renewTimeBytes, err := ioutil.ReadFile(storage.RenewTimerFile())
-	if err != nil {
-		return 0, err
-	}
-
-	renewalTime, err := time.Parse(time.RFC3339, string(renewTimeBytes))
-	if err != nil {
-		return 0, err
-	}
-
-	// The time read from the file was equal or more then 24 hours in the past,
-	// write the current time to the file and return true.
-	hoursSinceRenew := int(time.Now().UTC().Sub(renewalTime).Hours())
-
-	if hoursSinceRenew >= renewTimer {
-		return 0, nil
-	}
-
-	return hoursSinceRenew, nil
-}
-
 var (
 	// Let's Encrypt account email to use if none provided
 	DefaultEmail string
@@ -431,13 +296,14 @@ var (
 const (
 	// The base URL to the Let's Encrypt CA
 	// TODO: Staging API URL is: https://acme-staging.api.letsencrypt.org
+	// TODO: Production endpoint is: https://acme-v01.api.letsencrypt.org
 	caURL = "http://192.168.99.100:4000"
 
 	// The port to expose to the CA server for Simple HTTP Challenge
 	exposePort = "5001"
 
-	// Renewal Timer - Check renewals every x hours.
+	// How often to check certificates for renewal
-	renewTimer = 24
+	renewInterval = 24 * time.Hour
 )
 
 // KeySize represents the length of a key in bits.

config/letsencrypt/renew.go

@@ -0,0 +1,94 @@
+package letsencrypt
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"log"
+	"time"
+
+	"github.com/mholt/caddy/server"
+	"github.com/xenolf/lego/acme"
+)
+
+// keepCertificatesRenewed is a permanently-blocking function
+// that loops indefinitely and, on a regular schedule, checks
+// certificates for expiration and initiates a renewal of certs
+// that are expiring soon.
+func keepCertificatesRenewed(configs []server.Config) {
+	ticker := time.Tick(renewInterval)
+	for range ticker {
+		if err := processCertificateRenewal(configs); err != nil {
+			log.Printf("[ERROR] cert renewal: %v", err)
+		}
+	}
+}
+
+// checkCertificateRenewal loops through all configured
+// sites and looks for certificates to renew. Nothing is mutated
+// through this function. The changes happen directly on disk.
+func processCertificateRenewal(configs []server.Config) error {
+	log.Print("[INFO] Processing certificate renewals...")
+
+	for _, cfg := range configs {
+		// Check if this entry is TLS enabled and managed by LE
+		if !cfg.TLS.Enabled || !existingCertAndKey(cfg.Host) {
+			continue
+		}
+
+		// Read the certificate and get the NotAfter time.
+		certBytes, err := ioutil.ReadFile(storage.SiteCertFile(cfg.Host))
+		if err != nil {
+			return err
+		}
+		expTime, err := acme.GetPEMCertExpiration(certBytes)
+		if err != nil {
+			return err
+		}
+
+		// The time returned from the certificate is always in UTC.
+		// So calculate the time left with local time as UTC.
+		// Directly convert it to days for the following checks.
+		daysLeft := int(expTime.Sub(time.Now().UTC()).Hours() / 24)
+
+		// Renew on two or less days remaining.
+		if daysLeft <= 2 {
+			log.Printf("[WARN] There are %d days left on the certificate of %s. Trying to renew now.", daysLeft, cfg.Host)
+			client, err := newClient(getEmail(cfg))
+			if err != nil {
+				return err
+			}
+
+			// Read metadata
+			metaBytes, err := ioutil.ReadFile(storage.SiteMetaFile(cfg.Host))
+			if err != nil {
+				return err
+			}
+
+			privBytes, err := ioutil.ReadFile(storage.SiteKeyFile(cfg.Host))
+			if err != nil {
+				return err
+			}
+
+			var certMeta acme.CertificateResource
+			err = json.Unmarshal(metaBytes, &certMeta)
+			certMeta.Certificate = certBytes
+			certMeta.PrivateKey = privBytes
+
+			// Renew certificate.
+			// TODO: revokeOld should be an option in the caddyfile
+			newCertMeta, err := client.RenewCertificate(certMeta, true)
+			if err != nil {
+				return err
+			}
+
+			saveCertsAndKeys([]acme.CertificateResource{newCertMeta})
+		}
+
+		// Warn on 14 days remaining
+		if daysLeft <= 14 {
+			log.Printf("[WARN] There are %d days left on the certificate of %s. Will renew on two days left.\n", daysLeft, cfg.Host)
+		}
+	}
+
+	return nil
+}

config/letsencrypt/storage.go

@@ -16,11 +16,6 @@ var storage = Storage(filepath.Join(app.DataFolder(), "letsencrypt"))
 // forming file paths derived from it.
 type Storage string
 
-// RenewTimerFile returns the path to the file used for renewal timing.
-func (s Storage) RenewTimerFile() string {
-	return filepath.Join(string(s), "lastrenew")
-}
-
 // Sites gets the directory that stores site certificate and keys.
 func (s Storage) Sites() string {
 	return filepath.Join(string(s), "sites")