Added LeveledFormatLogger (Printf-like logger)

client.go

@@ -277,6 +277,15 @@ type Logger interface {
 	Printf(string, ...interface{})
 }
 
+// LeveledFormatLogger interface allows to use logger libraries that use formatted
+// leveled methods for loging
+type LeveledFormatLogger interface {
+	Infof(string, ...interface{})
+	Debugf(string, ...interface{})
+	Warnf(string, ...interface{})
+	Errorf(string, ...interface{})
+}
+
 // LeveledLogger is an interface that can be implemented by any logger or a
 // logger wrapper to provide leveled logging. The methods accept a message
 // string and a variadic number of key-value pairs. For log.Printf style
@@ -299,6 +308,16 @@ func (h hookLogger) Printf(s string, args ...interface{}) {
 	h.Info(fmt.Sprintf(s, args...))
 }
 
+// hookFormatLogger adapts an LeveledFormatLogger to Logger for use by the existing hook
+// functions without changing the API.
+type hookFormatLogger struct {
+	LeveledFormatLogger
+}
+
+func (h hookFormatLogger) Printf(s string, args ...interface{}) {
+	h.Infof(fmt.Sprintf(s, args...))
+}
+
 // RequestLogHook allows a function to run before each retry. The HTTP
 // request which will be made, and the retry number (0 for the initial
 // request) are available to users. The internal logger is exposed to
@@ -385,11 +404,11 @@ func (c *Client) logger() interface{} {
 		}
 
 		switch c.Logger.(type) {
-		case Logger, LeveledLogger:
+		case Logger, LeveledLogger, LeveledFormatLogger:
 			// ok
 		default:
 			// This should happen in dev when they are setting Logger and work on code, not in prod.
-			panic(fmt.Sprintf("invalid logger type passed, must be Logger or LeveledLogger, was %T", c.Logger))
+			panic(fmt.Sprintf("invalid logger type passed, must be Logger, LeveledLogger or LeveledFormatLogger, was %T", c.Logger))
 		}
 	})
 
@@ -569,6 +588,8 @@ func (c *Client) Do(req *Request) (*http.Response, error) {
 
 	if logger != nil {
 		switch v := logger.(type) {
+		case LeveledFormatLogger:
+			v.Debugf("%s %s: performing request", req.Method, req.URL)
 		case LeveledLogger:
 			v.Debug("performing request", "method", req.Method, "url", req.URL)
 		case Logger:
@@ -602,6 +623,8 @@ func (c *Client) Do(req *Request) (*http.Response, error) {
 
 		if c.RequestLogHook != nil {
 			switch v := logger.(type) {
+			case LeveledFormatLogger:
+				c.RequestLogHook(hookFormatLogger{v}, req.Request, i)
 			case LeveledLogger:
 				c.RequestLogHook(hookLogger{v}, req.Request, i)
 			case Logger:
@@ -622,6 +645,8 @@ func (c *Client) Do(req *Request) (*http.Response, error) {
 
 		if doErr != nil {
 			switch v := logger.(type) {
+			case LeveledFormatLogger:
+				v.Errorf("%s %s: request failed: %s", req.Method, req.URL, doErr)
 			case LeveledLogger:
 				v.Error("request failed", "error", doErr, "method", req.Method, "url", req.URL)
 			case Logger:
@@ -633,6 +658,8 @@ func (c *Client) Do(req *Request) (*http.Response, error) {
 			if c.ResponseLogHook != nil {
 				// Call the response logger function if provided.
 				switch v := logger.(type) {
+				case LeveledFormatLogger:
+					c.ResponseLogHook(hookFormatLogger{v}, resp)
 				case LeveledLogger:
 					c.ResponseLogHook(hookLogger{v}, resp)
 				case Logger:
@@ -666,6 +693,8 @@ func (c *Client) Do(req *Request) (*http.Response, error) {
 		}
 		if logger != nil {
 			switch v := logger.(type) {
+			case LeveledFormatLogger:
+				v.Debugf("%s: retrying request in %s (%d left)", desc, wait, remain)
 			case LeveledLogger:
 				v.Debug("retrying request", "request", desc, "timeout", wait, "remaining", remain)
 			case Logger:
@@ -720,6 +749,8 @@ func (c *Client) drainBody(body io.ReadCloser) {
 	if err != nil {
 		if c.logger() != nil {
 			switch v := c.logger().(type) {
+			case LeveledFormatLogger:
+				v.Errorf("error reading response body: %s", err)
 			case LeveledLogger:
 				v.Error("error reading response body", "error", err)
 			case Logger: