Fix #926 cache warmer and method signature

pkg/cache/cache.go

@@ -35,6 +35,40 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+type NotFoundErr struct {
+	msg string
+}
+
+func (e NotFoundErr) Error() string {
+	return e.msg
+}
+
+type ExpiredErr struct {
+	msg string
+}
+
+func (e ExpiredErr) Error() string {
+	return e.msg
+}
+
+func IsNotFound(e error) bool {
+	switch e.(type) {
+	case NotFoundErr:
+		return true
+	}
+
+	return false
+}
+
+func IsExpired(e error) bool {
+	switch e.(type) {
+	case ExpiredErr:
+		return true
+	}
+
+	return false
+}
+
 // LayerCache is the layer cache
 type LayerCache interface {
 	RetrieveLayer(string) (v1.Image, error)
@@ -124,15 +158,17 @@ func LocalSource(opts *config.CacheOptions, cacheKey string) (v1.Image, error) {
 
 	fi, err := os.Stat(path)
 	if err != nil {
-		logrus.Debugf("No file found for cache key %v %v", cacheKey, err)
+		msg := fmt.Sprintf("No file found for cache key %v %v", cacheKey, err)
-		return nil, nil
+		logrus.Debug(msg)
+		return nil, NotFoundErr{msg: msg}
 	}
 
 	// A stale cache is a bad cache
 	expiry := fi.ModTime().Add(opts.CacheTTL)
 	if expiry.Before(time.Now()) {
-		logrus.Debugf("Cached image is too old: %v", fi.ModTime())
+		msg := fmt.Sprintf("Cached image is too old: %v", fi.ModTime())
-		return nil, nil
+		logrus.Debug(msg)
+		return nil, ExpiredErr{msg: msg}
 	}
 
 	logrus.Infof("Found %s in local cache", cacheKey)

pkg/cache/warm.go

@@ -54,7 +54,7 @@ func WarmCache(opts *config.WarmerOptions) error {
 
 		if !opts.Force {
 			_, err := LocalSource(&opts.CacheOptions, digest.String())
-			if err == nil {
+			if err == nil || IsExpired(err) {
 				continue
 			}
 		}

pkg/util/image_util.go

@@ -75,12 +75,19 @@ func RetrieveSourceImage(stage config.KanikoStage, opts *config.KanikoOptions) (
 	if opts.CacheDir != "" {
 		cachedImage, err := cachedImage(opts, currentBaseName)
 		if err != nil {
-			logrus.Errorf("Error while retrieving image from cache: %v %v", currentBaseName, err)
+			switch {
+			case cache.IsNotFound(err):
+				logrus.Debugf("Image %v not found in cache", currentBaseName)
+			case cache.IsExpired(err):
+				logrus.Debugf("Image %v found in cache but was expired", currentBaseName)
+			default:
+				logrus.Errorf("Error while retrieving image from cache: %v %v", currentBaseName, err)
+			}
 		} else if cachedImage != nil {
 			return cachedImage, nil
 		}
 	}
-	logrus.Infof("Image %v not found in cache", currentBaseName)
+
 	// Otherwise, initialize image as usual
 	return RetrieveRemoteImage(currentBaseName, opts)
 }