finish the check

16 files changed, 491 insertions, 109 deletions

diff --git a/service/health/service.go b/service/health/service.go
index c0be68e0..a730de7e 100644
--- a/service/health/service.go
+++ b/service/health/service.go
@@ -2,6 +2,7 @@ package health
 
 import (
 	"context"
+	"fmt"
 	"net/http"
 	"sync"
 
@@ -47,7 +48,13 @@ func (s *Service) Stop() {
 
 	if s.http != nil {
 		// gracefully stop the server
-		go s.http.Shutdown(context.Background())
+		go func() {
+			err := s.http.Shutdown(context.Background())
+			if err != nil {
+				// TODO how to log error here?
+				fmt.Println(fmt.Errorf("error shutting down the server: error %v", err))
+			}
+		}()
 	}
 }
 
diff --git a/service/http/h2c_test.go b/service/http/h2c_test.go
index d806e5ff..7bbc30ac 100644
--- a/service/http/h2c_test.go
+++ b/service/http/h2c_test.go
@@ -36,7 +36,12 @@ func Test_Service_H2C(t *testing.T) {
 	// should do nothing
 	s.(*Service).Stop()
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error serving: %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -49,7 +54,12 @@ func Test_Service_H2C(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("fail to close the Body: error %v", err)
+		}
+	}()
 
 	assert.Equal(t, "101 Switching Protocols", r.Status)
 
diff --git a/service/http/handler.go b/service/http/handler.go
index a4da224d..4de33844 100644
--- a/service/http/handler.go
+++ b/service/http/handler.go
@@ -120,7 +120,10 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	h.handleResponse(req, resp, start)
-	resp.Write(w)
+	err = resp.Write(w)
+	if err != nil {
+		h.handleError(w, r, err, start)
+	}
 }
 
 // handleError sends error.
@@ -128,7 +131,10 @@ func (h *Handler) handleError(w http.ResponseWriter, r *http.Request, err error,
 	h.throw(EventError, &ErrorEvent{Request: r, Error: err, start: start, elapsed: time.Since(start)})
 
 	w.WriteHeader(500)
-	w.Write([]byte(err.Error()))
+	_, err = w.Write([]byte(err.Error()))
+	if err != nil {
+		h.throw(EventError, &ErrorEvent{Request: r, Error: err, start: start, elapsed: time.Since(start)})
+	}
 }
 
 // handleResponse triggers response event.
diff --git a/service/http/handler_test.go b/service/http/handler_test.go
index 91f0ca2b..0db999c9 100644
--- a/service/http/handler_test.go
+++ b/service/http/handler_test.go
@@ -24,6 +24,9 @@ func get(url string) (string, *http.Response, error) {
 		return "", nil, err
 	}
 	b, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return "", nil, err
+	}
 
 	err = r.Body.Close()
 	if err != nil {
@@ -49,6 +52,9 @@ func getHeader(url string, h map[string]string) (string, *http.Response, error)
 	}
 
 	b, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return "", nil, err
+	}
 
 	err = r.Body.Close()
 	if err != nil {
diff --git a/service/http/response.go b/service/http/response.go
index 8bd770ec..7102f078 100644
--- a/service/http/response.go
+++ b/service/http/response.go
@@ -35,7 +35,10 @@ func (r *Response) Write(w http.ResponseWriter) error {
 		for _, v := range h {
 			if n == "http2-push" {
 				if pusher, ok := w.(http.Pusher); ok {
-					pusher.Push(v, nil)
+					err := pusher.Push(v, nil)
+					if err != nil {
+						return err
+					}
 				}
 
 				continue
@@ -48,7 +51,10 @@ func (r *Response) Write(w http.ResponseWriter) error {
 	w.WriteHeader(r.Status)
 
 	if data, ok := r.body.([]byte); ok {
-		w.Write(data)
+		_, err := w.Write(data)
+		if err != nil {
+			return err
+		}
 	}
 
 	if rc, ok := r.body.(io.Reader); ok {
diff --git a/service/http/rpc_test.go b/service/http/rpc_test.go
index 669b201c..0e4b2c0a 100644
--- a/service/http/rpc_test.go
+++ b/service/http/rpc_test.go
@@ -49,7 +49,12 @@ func Test_RPC(t *testing.T) {
 	s2, _ := c.Get(rpc.ID)
 	rs := s2.(*rpc.Service)
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -110,7 +115,12 @@ func Test_RPC_Unix(t *testing.T) {
 	s2, _ := c.Get(rpc.ID)
 	rs := s2.(*rpc.Service)
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -164,7 +174,12 @@ func Test_Workers(t *testing.T) {
 	s2, _ := c.Get(rpc.ID)
 	rs := s2.(*rpc.Service)
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
diff --git a/service/http/service.go b/service/http/service.go
index 58038acb..1547538b 100644
--- a/service/http/service.go
+++ b/service/http/service.go
@@ -157,15 +157,36 @@ func (s *Service) Stop() {
 	defer s.mu.Unlock()
 
 	if s.fcgi != nil {
-		go s.fcgi.Shutdown(context.Background())
+		go func() {
+			err := s.fcgi.Shutdown(context.Background())
+			if err != nil {
+				// TODO think about returning error from this Stop function
+				// Stop() error
+				// push error from goroutines to the channel and block unil error or success shutdown or timeout
+				fmt.Println(fmt.Errorf("error shutting down the server, error: %v", err))
+				return
+			}
+		}()
 	}
 
 	if s.https != nil {
-		go s.https.Shutdown(context.Background())
+		go func() {
+			err := s.fcgi.Shutdown(context.Background())
+			if err != nil {
+				fmt.Println(fmt.Errorf("error shutting down the server, error: %v", err))
+				return
+			}
+		}()
 	}
 
 	if s.http != nil {
-		go s.http.Shutdown(context.Background())
+		go func() {
+			err := s.fcgi.Shutdown(context.Background())
+			if err != nil {
+				fmt.Println(fmt.Errorf("error shutting down the server, error: %v", err))
+				return
+			}
+		}()
 	}
 }
 
diff --git a/service/http/service_test.go b/service/http/service_test.go
index 69cb7003..bfc10971 100644
--- a/service/http/service_test.go
+++ b/service/http/service_test.go
@@ -53,7 +53,10 @@ func Test_Service_NoConfig(t *testing.T) {
 	c := service.NewContainer(logger)
 	c.Register(ID, &Service{})
 
-	c.Init(&testCfg{httpCfg: `{"Enable":true}`})
+	err := c.Init(&testCfg{httpCfg: `{"Enable":true}`})
+	if err != nil {
+		t.Errorf("error during the Init: error %v", err)
+	}
 
 	s, st := c.Get(ID)
 	assert.NotNil(t, s)
@@ -138,7 +141,12 @@ func Test_Service_Echo(t *testing.T) {
 	// should do nothing
 	s.(*Service).Stop()
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("serve error: %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -147,7 +155,12 @@ func Test_Service_Echo(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("error closing the Body: error %v", err)
+		}
+	}()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -191,7 +204,12 @@ func Test_Service_Env(t *testing.T) {
 	// should do nothing
 	s.(*Service).Stop()
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("serve error: %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -200,7 +218,12 @@ func Test_Service_Env(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("error closing the Body: error %v", err)
+		}
+	}()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -249,7 +272,12 @@ func Test_Service_ErrorEcho(t *testing.T) {
 		}
 	})
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("serve error: %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -258,7 +286,12 @@ func Test_Service_ErrorEcho(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("error closing the Body: error %v", err)
+		}
+	}()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -304,14 +337,22 @@ func Test_Service_Middleware(t *testing.T) {
 		return func(w http.ResponseWriter, r *http.Request) {
 			if r.URL.Path == "/halt" {
 				w.WriteHeader(500)
-				w.Write([]byte("halted"))
+				_, err := w.Write([]byte("halted"))
+				if err != nil {
+					t.Errorf("error writing the data to the http reply: error %v", err)
+				}
 			} else {
 				f(w, r)
 			}
 		}
 	})
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("serve error: %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -320,7 +361,6 @@ func Test_Service_Middleware(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -329,19 +369,27 @@ func Test_Service_Middleware(t *testing.T) {
 	assert.Equal(t, 201, r.StatusCode)
 	assert.Equal(t, "WORLD", string(b))
 
+	err = r.Body.Close()
+	if err != nil {
+		t.Errorf("error closing the Body: error %v", err)
+	}
+
 	req, err = http.NewRequest("GET", "http://localhost:6029/halt", nil)
 	assert.NoError(t, err)
 
 	r, err = http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
-
 	b, err = ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
 
 	assert.NoError(t, err)
 	assert.Equal(t, 500, r.StatusCode)
 	assert.Equal(t, "halted", string(b))
+
+	err = r.Body.Close()
+	if err != nil {
+		t.Errorf("error closing the Body: error %v", err)
+	}
 }
 
 func Test_Service_Listener(t *testing.T) {
@@ -381,7 +429,12 @@ func Test_Service_Listener(t *testing.T) {
 		}
 	})
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("serve error: %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 
 	c.Stop()
diff --git a/service/http/ssl_test.go b/service/http/ssl_test.go
index 63eb90b1..c9b4d090 100644
--- a/service/http/ssl_test.go
+++ b/service/http/ssl_test.go
@@ -47,7 +47,12 @@ func Test_SSL_Service_Echo(t *testing.T) {
 	// should do nothing
 	s.(*Service).Stop()
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -56,7 +61,12 @@ func Test_SSL_Service_Echo(t *testing.T) {
 
 	r, err := sslClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("fail to close the Body: error %v", err)
+		}
+	}()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -93,7 +103,12 @@ func Test_SSL_Service_NoRedirect(t *testing.T) {
 	// should do nothing
 	s.(*Service).Stop()
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -102,7 +117,12 @@ func Test_SSL_Service_NoRedirect(t *testing.T) {
 
 	r, err := sslClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("fail to close the Body: error %v", err)
+		}
+	}()
 
 	assert.Nil(t, r.TLS)
 
@@ -142,7 +162,12 @@ func Test_SSL_Service_Redirect(t *testing.T) {
 	// should do nothing
 	s.(*Service).Stop()
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -151,7 +176,12 @@ func Test_SSL_Service_Redirect(t *testing.T) {
 
 	r, err := sslClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("fail to close the Body: error %v", err)
+		}
+	}()
 
 	assert.NotNil(t, r.TLS)
 
@@ -191,7 +221,12 @@ func Test_SSL_Service_Push(t *testing.T) {
 	// should do nothing
 	s.(*Service).Stop()
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -200,7 +235,12 @@ func Test_SSL_Service_Push(t *testing.T) {
 
 	r, err := sslClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("fail to close the Body: error %v", err)
+		}
+	}()
 
 	assert.NotNil(t, r.TLS)
 
diff --git a/service/http/uploads.go b/service/http/uploads.go
index 7610ab28..7efa7e4a 100644
--- a/service/http/uploads.go
+++ b/service/http/uploads.go
@@ -2,6 +2,7 @@ package http
 
 import (
 	"encoding/json"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"mime/multipart"
@@ -51,7 +52,11 @@ func (u *Uploads) Open() {
 		wg.Add(1)
 		go func(f *FileUpload) {
 			defer wg.Done()
-			f.Open(u.cfg)
+			err := f.Open(u.cfg)
+			if err != nil {
+				// TODO handle error mechanism in goroutines
+				fmt.Println(fmt.Errorf("error opening the file: error %v", err))
+			}
 		}(f)
 	}
 
@@ -62,7 +67,11 @@ func (u *Uploads) Open() {
 func (u *Uploads) Clear() {
 	for _, f := range u.list {
 		if f.TempFilename != "" && exists(f.TempFilename) {
-			os.Remove(f.TempFilename)
+			err := os.Remove(f.TempFilename)
+			if err != nil {
+				// TODO error handling mechanism
+				fmt.Println(fmt.Errorf("error removing the file: error %v", err))
+			}
 		}
 	}
 }
@@ -99,7 +108,13 @@ func NewUpload(f *multipart.FileHeader) *FileUpload {
 }
 
 // Open moves file content into temporary file available for PHP.
-func (f *FileUpload) Open(cfg *UploadsConfig) error {
+// NOTE:
+// There is 2 deferred functions, and in case of getting 2 errors from both functions
+// error from close of temp file would be overwritten by error from the main file
+// STACK
+// DEFER FILE CLOSE (2)
+// DEFER TMP CLOSE  (1)
+func (f *FileUpload) Open(cfg *UploadsConfig) (err error) {
 	if cfg.Forbids(f.Name) {
 		f.Error = UploadErrorExtension
 		return nil
@@ -110,7 +125,12 @@ func (f *FileUpload) Open(cfg *UploadsConfig) error {
 		f.Error = UploadErrorNoFile
 		return err
 	}
-	defer file.Close()
+
+	defer func() {
+		// close the main file
+		err = file.Close()
+	}()
+
 
 	tmp, err := ioutil.TempFile(cfg.TmpDir(), "upload")
 	if err != nil {
@@ -120,7 +140,10 @@ func (f *FileUpload) Open(cfg *UploadsConfig) error {
 	}
 
 	f.TempFilename = tmp.Name()
-	defer tmp.Close()
+	defer func() {
+		// close the temp file
+		err = tmp.Close()
+	}()
 
 	if f.Size, err = io.Copy(tmp, file); err != nil {
 		f.Error = UploadErrorCantWrite
@@ -131,10 +154,8 @@ func (f *FileUpload) Open(cfg *UploadsConfig) error {
 
 // exists if file exists.
 func exists(path string) bool {
-	_, err := os.Stat(path)
-	if err == nil {
-		return true
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		return false
 	}
-
-	return false
+	return true
 }
diff --git a/service/http/uploads_test.go b/service/http/uploads_test.go
index 0fbf0e14..c5de224b 100644
--- a/service/http/uploads_test.go
+++ b/service/http/uploads_test.go
@@ -6,6 +6,7 @@ import (
 	"crypto/md5"
 	"encoding/hex"
 	"encoding/json"
+	"fmt"
 	"github.com/spiral/roadrunner"
 	"github.com/stretchr/testify/assert"
 	"io"
@@ -41,22 +42,43 @@ func TestHandler_Upload_File(t *testing.T) {
 	defer h.rr.Stop()
 
 	hs := &http.Server{Addr: ":8021", Handler: h}
-	defer hs.Shutdown(context.Background())
-
-	go func() { hs.ListenAndServe() }()
+	defer func() {
+		err := hs.Shutdown(context.Background())
+		if err != nil {
+			t.Errorf("error during the shutdown: error %v", err)
+		}
+	}()
+
+	go func() {
+		err := hs.ListenAndServe()
+		if err != nil {
+			t.Errorf("error listening the interface: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 10)
 
 	var mb bytes.Buffer
 	w := multipart.NewWriter(&mb)
 
 	f := mustOpen("uploads_test.go")
-	defer f.Close()
+	defer func() {
+		err := f.Close()
+		if err != nil {
+			t.Errorf("failed to close a file: error %v", err)
+		}
+	}()
 	fw, err := w.CreateFormFile("upload", f.Name())
 	assert.NotNil(t, fw)
 	assert.NoError(t, err)
-	io.Copy(fw, f)
+	_, err = io.Copy(fw, f)
+	if err != nil {
+		t.Errorf("error copying the file: error %v", err)
+	}
 
-	w.Close()
+	err = w.Close()
+	if err != nil {
+		t.Errorf("error closing the file: error %v", err)
+	}
 
 	req, err := http.NewRequest("POST", "http://localhost"+hs.Addr, &mb)
 	assert.NoError(t, err)
@@ -65,7 +87,12 @@ func TestHandler_Upload_File(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("error closing the Body: error %v", err)
+		}
+	}()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -102,22 +129,43 @@ func TestHandler_Upload_NestedFile(t *testing.T) {
 	defer h.rr.Stop()
 
 	hs := &http.Server{Addr: ":8021", Handler: h}
-	defer hs.Shutdown(context.Background())
-
-	go func() { hs.ListenAndServe() }()
+	defer func() {
+		err := hs.Shutdown(context.Background())
+		if err != nil {
+			t.Errorf("error during the shutdown: error %v", err)
+		}
+	}()
+
+	go func() {
+		err := hs.ListenAndServe()
+		if err != nil {
+			t.Errorf("error listening the interface: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 10)
 
 	var mb bytes.Buffer
 	w := multipart.NewWriter(&mb)
 
 	f := mustOpen("uploads_test.go")
-	defer f.Close()
+	defer func() {
+		err := f.Close()
+		if err != nil {
+			t.Errorf("failed to close a file: error %v", err)
+		}
+	}()
 	fw, err := w.CreateFormFile("upload[x][y][z][]", f.Name())
 	assert.NotNil(t, fw)
 	assert.NoError(t, err)
-	io.Copy(fw, f)
+	_, err = io.Copy(fw, f)
+	if err != nil {
+		t.Errorf("error copying the file: error %v", err)
+	}
 
-	w.Close()
+	err = w.Close()
+	if err != nil {
+		t.Errorf("error closing the file: error %v", err)
+	}
 
 	req, err := http.NewRequest("POST", "http://localhost"+hs.Addr, &mb)
 	assert.NoError(t, err)
@@ -126,7 +174,12 @@ func TestHandler_Upload_NestedFile(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("error closing the Body: error %v", err)
+		}
+	}()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -163,22 +216,43 @@ func TestHandler_Upload_File_NoTmpDir(t *testing.T) {
 	defer h.rr.Stop()
 
 	hs := &http.Server{Addr: ":8021", Handler: h}
-	defer hs.Shutdown(context.Background())
-
-	go func() { hs.ListenAndServe() }()
+	defer func() {
+		err := hs.Shutdown(context.Background())
+		if err != nil {
+			t.Errorf("error during the shutdown: error %v", err)
+		}
+	}()
+
+	go func() {
+		err := hs.ListenAndServe()
+		if err != nil {
+			t.Errorf("error listening the interface: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 10)
 
 	var mb bytes.Buffer
 	w := multipart.NewWriter(&mb)
 
 	f := mustOpen("uploads_test.go")
-	defer f.Close()
+	defer func() {
+		err := f.Close()
+		if err != nil {
+			t.Errorf("failed to close a file: error %v", err)
+		}
+	}()
 	fw, err := w.CreateFormFile("upload", f.Name())
 	assert.NotNil(t, fw)
 	assert.NoError(t, err)
-	io.Copy(fw, f)
+	_, err = io.Copy(fw, f)
+	if err != nil {
+		t.Errorf("error copying the file: error %v", err)
+	}
 
-	w.Close()
+	err = w.Close()
+	if err != nil {
+		t.Errorf("error closing the file: error %v", err)
+	}
 
 	req, err := http.NewRequest("POST", "http://localhost"+hs.Addr, &mb)
 	assert.NoError(t, err)
@@ -187,7 +261,12 @@ func TestHandler_Upload_File_NoTmpDir(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("error closing the Body: error %v", err)
+		}
+	}()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -224,22 +303,43 @@ func TestHandler_Upload_File_Forbids(t *testing.T) {
 	defer h.rr.Stop()
 
 	hs := &http.Server{Addr: ":8021", Handler: h}
-	defer hs.Shutdown(context.Background())
-
-	go func() { hs.ListenAndServe() }()
+	defer func() {
+		err := hs.Shutdown(context.Background())
+		if err != nil {
+			t.Errorf("error during the shutdown: error %v", err)
+		}
+	}()
+
+	go func() {
+		err := hs.ListenAndServe()
+		if err != nil {
+			t.Errorf("error listening the interface: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 10)
 
 	var mb bytes.Buffer
 	w := multipart.NewWriter(&mb)
 
 	f := mustOpen("uploads_test.go")
-	defer f.Close()
+	defer func() {
+		err := f.Close()
+		if err != nil {
+			t.Errorf("failed to close a file: error %v", err)
+		}
+	}()
 	fw, err := w.CreateFormFile("upload", f.Name())
 	assert.NotNil(t, fw)
 	assert.NoError(t, err)
-	io.Copy(fw, f)
+	_, err = io.Copy(fw, f)
+	if err != nil {
+		t.Errorf("error copying the file: error %v", err)
+	}
 
-	w.Close()
+	err = w.Close()
+	if err != nil {
+		t.Errorf("error closing the file: error %v", err)
+	}
 
 	req, err := http.NewRequest("POST", "http://localhost"+hs.Addr, &mb)
 	assert.NoError(t, err)
@@ -248,7 +348,12 @@ func TestHandler_Upload_File_Forbids(t *testing.T) {
 
 	r, err := http.DefaultClient.Do(req)
 	assert.NoError(t, err)
-	defer r.Body.Close()
+	defer func() {
+		err := r.Body.Close()
+		if err != nil {
+			t.Errorf("error closing the Body: error %v", err)
+		}
+	}()
 
 	b, err := ioutil.ReadAll(r.Body)
 	assert.NoError(t, err)
@@ -282,28 +387,47 @@ type fInfo struct {
 	MD5   string `json:"md5,omitempty"`
 }
 
-func fileString(f string, err int, mime string) string {
-	s, _ := os.Stat(f)
+func fileString(f string, errNo int, mime string) string {
+	s, err := os.Stat(f)
+	if err != nil {
+		fmt.Println(fmt.Errorf("error stat the file, error: %v", err))
+	}
+
+	ff, err := os.Open(f)
+	if err != nil {
+		fmt.Println(fmt.Errorf("error opening the file, error: %v", err))
+	}
+
+	defer func() {
+		er := ff.Close()
+		if er != nil {
+			fmt.Println(fmt.Errorf("error closing the file, error: %v", er))
+		}
+	}()
 
-	ff, _ := os.Open(f)
-	defer ff.Close()
 	h := md5.New()
-	io.Copy(h, ff)
+	_, err = io.Copy(h, ff)
+	if err != nil {
+		fmt.Println(fmt.Errorf("error copying the file, error: %v", err))
+	}
 
 	v := &fInfo{
 		Name:  s.Name(),
 		Size:  s.Size(),
-		Error: err,
+		Error: errNo,
 		Mime:  mime,
 		MD5:   hex.EncodeToString(h.Sum(nil)),
 	}
 
-	if err != 0 {
+	if errNo != 0 {
 		v.MD5 = ""
 		v.Size = 0
 	}
 
-	r, _ := json.Marshal(v)
+	r, err := json.Marshal(v)
+	if err != nil {
+		fmt.Println(fmt.Errorf("error marshalling fInfo, error: %v", err))
+	}
 	return string(r)
 
 }
diff --git a/service/metrics/rpc.go b/service/metrics/rpc.go
index ee8ef984..9e7de640 100644
--- a/service/metrics/rpc.go
+++ b/service/metrics/rpc.go
@@ -32,26 +32,26 @@ func (rpc *rpcServer) Add(m *Metric, ok *bool) (err error) {
 		return fmt.Errorf("undefined collector `%s`", m.Name)
 	}
 
-	switch c.(type) {
+	switch c := c.(type) {
 	case prometheus.Gauge:
-		c.(prometheus.Gauge).Add(m.Value)
+		c.Add(m.Value)
 
 	case *prometheus.GaugeVec:
 		if len(m.Labels) == 0 {
 			return fmt.Errorf("required labels for collector `%s`", m.Name)
 		}
 
-		c.(*prometheus.GaugeVec).WithLabelValues(m.Labels...).Add(m.Value)
+		c.WithLabelValues(m.Labels...).Add(m.Value)
 
 	case prometheus.Counter:
-		c.(prometheus.Counter).Add(m.Value)
+		c.Add(m.Value)
 
 	case *prometheus.CounterVec:
 		if len(m.Labels) == 0 {
 			return fmt.Errorf("required labels for collector `%s`", m.Name)
 		}
 
-		c.(*prometheus.CounterVec).WithLabelValues(m.Labels...).Add(m.Value)
+		c.WithLabelValues(m.Labels...).Add(m.Value)
 
 	default:
 		return fmt.Errorf("collector `%s` does not support method `Add`", m.Name)
@@ -74,16 +74,16 @@ func (rpc *rpcServer) Sub(m *Metric, ok *bool) (err error) {
 		return fmt.Errorf("undefined collector `%s`", m.Name)
 	}
 
-	switch c.(type) {
+	switch c := c.(type) {
 	case prometheus.Gauge:
-		c.(prometheus.Gauge).Sub(m.Value)
+		c.Sub(m.Value)
 
 	case *prometheus.GaugeVec:
 		if len(m.Labels) == 0 {
 			return fmt.Errorf("required labels for collector `%s`", m.Name)
 		}
 
-		c.(*prometheus.GaugeVec).WithLabelValues(m.Labels...).Sub(m.Value)
+		c.WithLabelValues(m.Labels...).Sub(m.Value)
 	default:
 		return fmt.Errorf("collector `%s` does not support method `Sub`", m.Name)
 	}
@@ -105,23 +105,23 @@ func (rpc *rpcServer) Observe(m *Metric, ok *bool) (err error) {
 		return fmt.Errorf("undefined collector `%s`", m.Name)
 	}
 
-	switch c.(type) {
+	switch c := c.(type) {
 	case *prometheus.SummaryVec:
 		if len(m.Labels) == 0 {
 			return fmt.Errorf("required labels for collector `%s`", m.Name)
 		}
 
-		c.(*prometheus.SummaryVec).WithLabelValues(m.Labels...).Observe(m.Value)
+		c.WithLabelValues(m.Labels...).Observe(m.Value)
 
 	case prometheus.Histogram:
-		c.(prometheus.Histogram).Observe(m.Value)
+		c.Observe(m.Value)
 
 	case *prometheus.HistogramVec:
 		if len(m.Labels) == 0 {
 			return fmt.Errorf("required labels for collector `%s`", m.Name)
 		}
 
-		c.(*prometheus.HistogramVec).WithLabelValues(m.Labels...).Observe(m.Value)
+		c.WithLabelValues(m.Labels...).Observe(m.Value)
 	default:
 		return fmt.Errorf("collector `%s` does not support method `Observe`", m.Name)
 	}
@@ -143,16 +143,16 @@ func (rpc *rpcServer) Set(m *Metric, ok *bool) (err error) {
 		return fmt.Errorf("undefined collector `%s`", m.Name)
 	}
 
-	switch c.(type) {
+	switch c := c.(type) {
 	case prometheus.Gauge:
-		c.(prometheus.Gauge).Set(m.Value)
+		c.Set(m.Value)
 
 	case *prometheus.GaugeVec:
 		if len(m.Labels) == 0 {
 			return fmt.Errorf("required labels for collector `%s`", m.Name)
 		}
 
-		c.(*prometheus.GaugeVec).WithLabelValues(m.Labels...).Set(m.Value)
+		c.WithLabelValues(m.Labels...).Set(m.Value)
 
 	default:
 		return fmt.Errorf("collector `%s` does not support method `Set`", m.Name)
diff --git a/service/metrics/rpc_test.go b/service/metrics/rpc_test.go
index 6d061f1d..feae927a 100644
--- a/service/metrics/rpc_test.go
+++ b/service/metrics/rpc_test.go
@@ -42,7 +42,12 @@ func setup(t *testing.T, metric string, portNum string) (*rpc2.Client, service.C
 
 	assert.True(t, s.(*Service).Enabled())
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 
 	client, err := rs.Client()
diff --git a/service/metrics/service.go b/service/metrics/service.go
index 4916b3e0..9e2a1a71 100644
--- a/service/metrics/service.go
+++ b/service/metrics/service.go
@@ -2,6 +2,7 @@ package metrics
 
 import (
 	"context"
+	"fmt"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/spiral/roadrunner/service/rpc"
@@ -86,7 +87,14 @@ func (s *Service) Stop() {
 
 	if s.http != nil {
 		// gracefully stop server
-		go s.http.Shutdown(context.Background())
+		go func() {
+			err := s.http.Shutdown(context.Background())
+			if err != nil {
+				// TODO how to show error message?
+				// Function should be Stop() error
+				fmt.Println(fmt.Errorf("error shutting down the server: error %v", err))
+			}
+		}()
 	}
 }
 
diff --git a/service/metrics/service_test.go b/service/metrics/service_test.go
index 0cf6fd95..62e6f6d7 100644
--- a/service/metrics/service_test.go
+++ b/service/metrics/service_test.go
@@ -43,9 +43,16 @@ func get(url string) (string, *http.Response, error) {
 	if err != nil {
 		return "", nil, err
 	}
-	defer r.Body.Close()
 
 	b, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		return "", nil, err
+	}
+
+	err = r.Body.Close()
+	if err != nil {
+		return "", nil, err
+	}
 	return string(b), r, err
 }
 
@@ -63,7 +70,12 @@ func TestService_Serve(t *testing.T) {
 	s, _ := c.Get(ID)
 	assert.NotNil(t, s)
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -94,7 +106,12 @@ func Test_ServiceCustomMetric(t *testing.T) {
 
 	assert.NoError(t, s.(*Service).Register(collector))
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -127,7 +144,12 @@ func Test_ServiceCustomMetricMust(t *testing.T) {
 
 	s.(*Service).MustRegister(collector)
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
@@ -160,7 +182,12 @@ func Test_ConfiguredMetric(t *testing.T) {
 
 	assert.True(t, s.(*Service).Enabled())
 
-	go func() { c.Serve() }()
+	go func() {
+		err := c.Serve()
+		if err != nil {
+			t.Errorf("error during the Serve: error %v", err)
+		}
+	}()
 	time.Sleep(time.Millisecond * 100)
 	defer c.Stop()
 
diff --git a/service/rpc/config_test.go b/service/rpc/config_test.go
index af261698..6791128b 100644
--- a/service/rpc/config_test.go
+++ b/service/rpc/config_test.go
@@ -40,7 +40,12 @@ func TestConfig_Listener(t *testing.T) {
 	ln, err := cfg.Listener()
 	assert.NoError(t, err)
 	assert.NotNil(t, ln)
-	defer ln.Close()
+	defer func() {
+		err := ln.Close()
+		if err != nil {
+			t.Errorf("error closing the listener: error %v", err)
+		}
+	}()
 
 	assert.Equal(t, "tcp", ln.Addr().Network())
 	assert.Equal(t, "[::]:18001", ln.Addr().String())
@@ -56,7 +61,12 @@ func TestConfig_ListenerUnix(t *testing.T) {
 	ln, err := cfg.Listener()
 	assert.NoError(t, err)
 	assert.NotNil(t, ln)
-	defer ln.Close()
+	defer func() {
+		err := ln.Close()
+		if err != nil {
+			t.Errorf("error closing the listener: error %v", err)
+		}
+	}()
 
 	assert.Equal(t, "unix", ln.Addr().Network())
 	assert.Equal(t, "file.sock", ln.Addr().String())
@@ -86,12 +96,22 @@ func TestConfig_Dialer(t *testing.T) {
 	cfg := &Config{Listen: "tcp://:18001"}
 
 	ln, _ := cfg.Listener()
-	defer ln.Close()
+	defer func() {
+		err := ln.Close()
+		if err != nil {
+			t.Errorf("error closing the listener: error %v", err)
+		}
+	}()
 
 	conn, err := cfg.Dialer()
 	assert.NoError(t, err)
 	assert.NotNil(t, conn)
-	defer conn.Close()
+	defer func() {
+		err := conn.Close()
+		if err != nil {
+			t.Errorf("error closing the connection: error %v", err)
+		}
+	}()
 
 	assert.Equal(t, "tcp", conn.RemoteAddr().Network())
 	assert.Equal(t, "127.0.0.1:18001", conn.RemoteAddr().String())
@@ -105,12 +125,22 @@ func TestConfig_DialerUnix(t *testing.T) {
 	cfg := &Config{Listen: "unix://file.sock"}
 
 	ln, _ := cfg.Listener()
-	defer ln.Close()
+	defer func() {
+		err := ln.Close()
+		if err != nil {
+			t.Errorf("error closing the listener: error %v", err)
+		}
+	}()
 
 	conn, err := cfg.Dialer()
 	assert.NoError(t, err)
 	assert.NotNil(t, conn)
-	defer conn.Close()
+	defer func() {
+		err := conn.Close()
+		if err != nil {
+			t.Errorf("error closing the connection: error %v", err)
+		}
+	}()
 
 	assert.Equal(t, "unix", conn.RemoteAddr().Network())
 	assert.Equal(t, "file.sock", conn.RemoteAddr().String())
@@ -138,7 +168,10 @@ func Test_Config_DialerErrorMethod(t *testing.T) {
 
 func Test_Config_Defaults(t *testing.T) {
 	c := &Config{}
-	c.InitDefaults()
+	err := c.InitDefaults()
+	if err != nil {
+		t.Errorf("error during the InitDefaults: error %v", err)
+	}
 	assert.Equal(t, true, c.Enable)
 	assert.Equal(t, "tcp://127.0.0.1:6001", c.Listen)
 }