add HEAD method support to Ping middleware, modernize code

- Ping middleware now handles both GET and HEAD methods for /ping endpoint
- HEAD returns 200 OK with headers but no body (useful for lightweight health checks)
- Update dependencies: golang.org/x/crypto 0.45.0 -> 0.46.0, golang.org/x/sys 0.38.0 -> 0.39.0
- Apply modernize linter fixes:
  - Replace interface{} with any
  - Use max() builtin instead of if/else
  - Use strings.SplitSeq for more efficient iteration

Author: umputun

.golangci.yml

@@ -19,6 +19,8 @@ linters:
     - unconvert
     - unparam
     - unused
+    - modernize
+    - testifylint
   settings:
     goconst:
       min-len: 2

benchmarks.go

@@ -156,10 +156,7 @@ func (b *Benchmarks) Stats(interval time.Duration) BenchmarkStats {
 	}
 
 	// ensure we calculate rate based on actual interval
-	actualInterval := fnInterval.Sub(stInterval)
-	if actualInterval < time.Second {
-		actualInterval = time.Second
-	}
+	actualInterval := max(fnInterval.Sub(stInterval), time.Second)
 
 	return BenchmarkStats{
 		Requests:        requests,

go.mod

@@ -4,12 +4,12 @@ go 1.24.0
 
 require (
 	github.com/stretchr/testify v1.10.0
-	golang.org/x/crypto v0.45.0
+	golang.org/x/crypto v0.46.0
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	golang.org/x/sys v0.38.0 // indirect
+	golang.org/x/sys v0.39.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -4,10 +4,10 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-golang.org/x/crypto v0.45.0 h1:jMBrvKuj23MTlT0bQEOBcAE0mjg8mK9RXFhRH6nyF3Q=
-golang.org/x/crypto v0.45.0/go.mod h1:XTGrrkGJve7CYK7J8PEww4aY7gM3qMCElcJQ8n8JdX4=
-golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
-golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
+golang.org/x/crypto v0.46.0 h1:cKRW/pmt1pKAfetfu+RCEvjvZkA9RimPbh7bhFjGVBU=
+golang.org/x/crypto v0.46.0/go.mod h1:Evb/oLKmMraqjZ2iQTwDwvCtJkczlDuTmdJXoZVzqU0=
+golang.org/x/sys v0.39.0 h1:CvCKL8MeisomCi6qNZ+wbb0DN9E5AATixKsvNtMoMFk=
+golang.org/x/sys v0.39.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

gzip.go

@@ -20,7 +20,7 @@ var gzDefaultContentTypes = []string{
 }
 
 var gzPool = sync.Pool{
-	New: func() interface{} { return gzip.NewWriter(io.Discard) },
+	New: func() any { return gzip.NewWriter(io.Discard) },
 }
 
 type gzipResponseWriter struct {

logger/logger.go

@@ -32,7 +32,7 @@ type Middleware struct {
 
 // Backend is logging backend
 type Backend interface {
-	Logf(format string, args ...interface{})
+	Logf(format string, args ...any)
 }
 
 type logParts struct {
@@ -51,7 +51,7 @@ type logParts struct {
 
 type stdBackend struct{}
 
-func (s stdBackend) Logf(format string, args ...interface{}) {
+func (s stdBackend) Logf(format string, args ...any) {
 	log.Printf(format, args...)
 }
 

middleware.go

@@ -36,14 +36,17 @@ func AppInfo(app, author, version string) func(http.Handler) http.Handler {
 	return f
 }
 
-// Ping middleware response with pong to /ping. Stops chain if ping request detected
+// Ping middleware response with pong to /ping. Stops chain if ping request detected.
+// Handles both GET and HEAD methods - HEAD returns headers only without body,
+// which is useful for lightweight health checks by monitoring tools.
 func Ping(next http.Handler) http.Handler {
 	fn := func(w http.ResponseWriter, r *http.Request) {
-
-		if r.Method == "GET" && strings.HasSuffix(strings.ToLower(r.URL.Path), "/ping") {
+		if (r.Method == "GET" || r.Method == "HEAD") && strings.HasSuffix(strings.ToLower(r.URL.Path), "/ping") {
 			w.Header().Set("Content-Type", "text/plain")
 			w.WriteHeader(http.StatusOK)
-			_, _ = w.Write([]byte("pong"))
+			if r.Method == "GET" {
+				_, _ = w.Write([]byte("pong"))
+			}
 			return
 		}
 		next.ServeHTTP(w, r)

middleware_test.go

@@ -46,29 +46,58 @@ func TestMiddleware_AppInfo(t *testing.T) {
 }
 
 func TestMiddleware_Ping(t *testing.T) {
-
 	handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		_, err := w.Write([]byte("blah blah"))
 		require.NoError(t, err)
 	})
 	ts := httptest.NewServer(Ping(handler))
 	defer ts.Close()
 
-	resp, err := http.Get(ts.URL + "/ping")
-	require.Nil(t, err)
-	assert.Equal(t, 200, resp.StatusCode)
-	defer resp.Body.Close()
-	b, err := io.ReadAll(resp.Body)
-	assert.NoError(t, err)
-	assert.Equal(t, "pong", string(b))
+	t.Run("GET returns pong", func(t *testing.T) {
+		resp, err := http.Get(ts.URL + "/ping")
+		require.NoError(t, err)
+		defer resp.Body.Close()
+		assert.Equal(t, http.StatusOK, resp.StatusCode)
+		assert.Equal(t, "text/plain", resp.Header.Get("Content-Type"))
+		b, err := io.ReadAll(resp.Body)
+		assert.NoError(t, err)
+		assert.Equal(t, "pong", string(b))
+	})
 
-	resp, err = http.Get(ts.URL + "/blah")
-	require.Nil(t, err)
-	assert.Equal(t, 200, resp.StatusCode)
-	defer resp.Body.Close()
-	b, err = io.ReadAll(resp.Body)
-	assert.NoError(t, err)
-	assert.Equal(t, "blah blah", string(b))
+	t.Run("HEAD returns 200 with no body", func(t *testing.T) {
+		req, err := http.NewRequest(http.MethodHead, ts.URL+"/ping", http.NoBody)
+		require.NoError(t, err)
+		resp, err := http.DefaultClient.Do(req)
+		require.NoError(t, err)
+		defer resp.Body.Close()
+		assert.Equal(t, http.StatusOK, resp.StatusCode)
+		assert.Equal(t, "text/plain", resp.Header.Get("Content-Type"))
+		b, err := io.ReadAll(resp.Body)
+		assert.NoError(t, err)
+		assert.Empty(t, b, "HEAD should return empty body")
+	})
+
+	t.Run("POST passes to next handler", func(t *testing.T) {
+		req, err := http.NewRequest(http.MethodPost, ts.URL+"/ping", http.NoBody)
+		require.NoError(t, err)
+		resp, err := http.DefaultClient.Do(req)
+		require.NoError(t, err)
+		defer resp.Body.Close()
+		assert.Equal(t, http.StatusOK, resp.StatusCode)
+		b, err := io.ReadAll(resp.Body)
+		assert.NoError(t, err)
+		assert.Equal(t, "blah blah", string(b))
+	})
+
+	t.Run("other paths pass to next handler", func(t *testing.T) {
+		resp, err := http.Get(ts.URL + "/blah")
+		require.NoError(t, err)
+		defer resp.Body.Close()
+		assert.Equal(t, http.StatusOK, resp.StatusCode)
+		b, err := io.ReadAll(resp.Body)
+		assert.NoError(t, err)
+		assert.Equal(t, "blah blah", string(b))
+	})
 }
 
 func TestMiddleware_Recoverer(t *testing.T) {

realip/real.go

@@ -58,8 +58,7 @@ func Get(r *http.Request) (string, error) {
 
 	// check X-Forwarded-For, find leftmost public IP
 	if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
-		addresses := strings.Split(xff, ",")
-		for _, addr := range addresses {
+		for addr := range strings.SplitSeq(xff, ",") {
 			ip := strings.TrimSpace(addr)
 			if parsedIP := net.ParseIP(ip); isPublicIP(parsedIP) {
 				return ip, nil

rest.go

@@ -13,7 +13,7 @@ import (
 type JSON map[string]any
 
 // RenderJSON sends data as json
-func RenderJSON(w http.ResponseWriter, data interface{}) {
+func RenderJSON(w http.ResponseWriter, data any) {
 	buf := &bytes.Buffer{}
 	enc := json.NewEncoder(buf)
 	enc.SetEscapeHTML(true)
@@ -35,9 +35,8 @@ func RenderJSONFromBytes(w http.ResponseWriter, r *http.Request, data []byte) er
 }
 
 // RenderJSONWithHTML allows html tags and forces charset=utf-8
-func RenderJSONWithHTML(w http.ResponseWriter, r *http.Request, v interface{}) error {
-
-	encodeJSONWithHTML := func(v interface{}) ([]byte, error) {
+func RenderJSONWithHTML(w http.ResponseWriter, r *http.Request, v any) error {
+	encodeJSONWithHTML := func(v any) ([]byte, error) {
 		buf := &bytes.Buffer{}
 		enc := json.NewEncoder(buf)
 		enc.SetEscapeHTML(false)
@@ -55,7 +54,7 @@ func RenderJSONWithHTML(w http.ResponseWriter, r *http.Request, v interface{}) e
 }
 
 // renderJSONWithStatus sends data as json and enforces status code
-func renderJSONWithStatus(w http.ResponseWriter, data interface{}, code int) {
+func renderJSONWithStatus(w http.ResponseWriter, data any, code int) {
 	buf := &bytes.Buffer{}
 	enc := json.NewEncoder(buf)
 	enc.SetEscapeHTML(true)