feat: implement logging contract

This commit removes the hard requirement to use logrus, and enables any log lib to be used, which fulfills the LoggerContract.

For backwards compatibility, logrus is kept as the default though.

cache.go

@@ -15,13 +15,20 @@ var (
 	ErrNotImplemented = errors.New("not implemented")
 )
 
+// LoggerContract defines the logging methods required by the cache.
+// This allows to use different kinds of logging libraries.
+type LoggerContract interface {
+	Infof(format string, args ...interface{})
+	Debugf(format string, args ...interface{})
+}
+
 // Cache is a simple caching implementation to reuse JWTs till they expire.
 type Cache struct {
 	jwt      string
 	validity time.Time
 
 	name      string
-	logger    *logrus.Logger
+	logger    LoggerContract
 	headroom  time.Duration
 	tokenFunc func(ctx context.Context) (string, error)
 }
@@ -53,7 +60,7 @@ func NewCache(opts ...Option) *Cache {
 
 type config struct {
 	name      string
-	logger    *logrus.Logger
+	logger    LoggerContract
 	headroom  time.Duration
 	tokenFunc func(ctx context.Context) (string, error)
 }
@@ -71,7 +78,7 @@ func Name(name string) Option {
 
 // Name sets the logger to be used.
 // The default is the logrus default logger.
-func Logger(logger *logrus.Logger) Option {
+func Logger(logger LoggerContract) Option {
 	return func(c *config) {
 		c.logger = logger
 	}

cachemap.go

@@ -16,7 +16,7 @@ type CacheMap struct {
 	lock   *sync.RWMutex
 
 	name      string
-	logger    *logrus.Logger
+	logger    LoggerContract
 	headroom  time.Duration
 	tokenFunc func(ctx context.Context, key string) (string, error)
 }
@@ -51,7 +51,7 @@ func NewCacheMap(opts ...MapOption) *CacheMap {
 
 type mapConfig struct {
 	name      string
-	logger    *logrus.Logger
+	logger    LoggerContract
 	headroom  time.Duration
 	tokenFunc func(ctx context.Context, key string) (string, error)
 }
@@ -69,7 +69,7 @@ func MapName(name string) MapOption {
 
 // MapLogger sets the logger to be used.
 // The default is the logrus default logger.
-func MapLogger(logger *logrus.Logger) MapOption {
+func MapLogger(logger LoggerContract) MapOption {
 	return func(c *mapConfig) {
 		c.logger = logger
 	}