use http consts for request methods

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

context/http_test.go

@@ -14,7 +14,7 @@ func TestWithRequest(t *testing.T) {
 	var req http.Request
 
 	start := time.Now()
-	req.Method = "GET"
+	req.Method = http.MethodGet
 	req.Host = "example.com"
 	req.RequestURI = "/test-test"
 	req.Header = make(http.Header)
@@ -253,7 +253,7 @@ func TestRemoteAddr(t *testing.T) {
 
 	// X-Forwarded-For set by proxy
 	expectedRemote = "127.0.0.1"
-	proxyReq, err := http.NewRequest("GET", frontend.URL, nil)
+	proxyReq, err := http.NewRequest(http.MethodGet, frontend.URL, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -264,7 +264,7 @@ func TestRemoteAddr(t *testing.T) {
 	}
 
 	// RemoteAddr in X-Real-Ip
-	getReq, err := http.NewRequest("GET", backend.URL, nil)
+	getReq, err := http.NewRequest(http.MethodGet, backend.URL, nil)
 	if err != nil {
 		t.Fatal(err)
 	}

contrib/token-server/main.go

@@ -96,8 +96,8 @@ func main() {
 	}
 
 	router := mux.NewRouter()
-	router.Path("/token/").Methods("GET").Handler(handlerWithContext(ctx, ts.getToken))
+	router.Path("/token/").Methods(http.MethodGet).Handler(handlerWithContext(ctx, ts.getToken))
-	router.Path("/token/").Methods("POST").Handler(handlerWithContext(ctx, ts.postToken))
+	router.Path("/token/").Methods(http.MethodPost).Handler(handlerWithContext(ctx, ts.postToken))
 
 	if cert == "" {
 		err = http.ListenAndServe(addr, router)

health/api/api.go

@@ -13,7 +13,7 @@ var (
 
 // DownHandler registers a manual_http_status that always returns an Error
 func DownHandler(w http.ResponseWriter, r *http.Request) {
-	if r.Method == "POST" {
+	if r.Method == http.MethodPost {
 		updater.Update(errors.New("manual Check"))
 	} else {
 		w.WriteHeader(http.StatusNotFound)
@@ -22,7 +22,7 @@ func DownHandler(w http.ResponseWriter, r *http.Request) {
 
 // UpHandler registers a manual_http_status that always returns nil
 func UpHandler(w http.ResponseWriter, r *http.Request) {
-	if r.Method == "POST" {
+	if r.Method == http.MethodPost {
 		updater.Update(nil)
 	} else {
 		w.WriteHeader(http.StatusNotFound)

health/api/api_test.go

@@ -13,7 +13,7 @@ import (
 func TestGETDownHandlerDoesNotChangeStatus(t *testing.T) {
 	recorder := httptest.NewRecorder()
 
-	req, err := http.NewRequest("GET", "https://fakeurl.com/debug/health/down", nil)
+	req, err := http.NewRequest(http.MethodGet, "https://fakeurl.com/debug/health/down", nil)
 	if err != nil {
 		t.Errorf("Failed to create request.")
 	}
@@ -30,7 +30,7 @@ func TestGETDownHandlerDoesNotChangeStatus(t *testing.T) {
 func TestGETUpHandlerDoesNotChangeStatus(t *testing.T) {
 	recorder := httptest.NewRecorder()
 
-	req, err := http.NewRequest("GET", "https://fakeurl.com/debug/health/up", nil)
+	req, err := http.NewRequest(http.MethodGet, "https://fakeurl.com/debug/health/up", nil)
 	if err != nil {
 		t.Errorf("Failed to create request.")
 	}
@@ -48,7 +48,7 @@ func TestGETUpHandlerDoesNotChangeStatus(t *testing.T) {
 func TestPOSTDownHandlerChangeStatus(t *testing.T) {
 	recorder := httptest.NewRecorder()
 
-	req, err := http.NewRequest("POST", "https://fakeurl.com/debug/health/down", nil)
+	req, err := http.NewRequest(http.MethodPost, "https://fakeurl.com/debug/health/down", nil)
 	if err != nil {
 		t.Errorf("Failed to create request.")
 	}
@@ -69,7 +69,7 @@ func TestPOSTDownHandlerChangeStatus(t *testing.T) {
 func TestPOSTUpHandlerChangeStatus(t *testing.T) {
 	recorder := httptest.NewRecorder()
 
-	req, err := http.NewRequest("POST", "https://fakeurl.com/debug/health/up", nil)
+	req, err := http.NewRequest(http.MethodPost, "https://fakeurl.com/debug/health/up", nil)
 	if err != nil {
 		t.Errorf("Failed to create request.")
 	}

health/checks/checks.go

@@ -40,7 +40,7 @@ func HTTPChecker(r string, statusCode int, timeout time.Duration, headers http.H
 		client := http.Client{
 			Timeout: timeout,
 		}
-		req, err := http.NewRequest("HEAD", r, nil)
+		req, err := http.NewRequest(http.MethodHead, r, nil)
 		if err != nil {
 			return errors.New("error creating request: " + r)
 		}

health/health.go

@@ -242,7 +242,7 @@ func RegisterPeriodicThresholdFunc(name string, period time.Duration, threshold
 // and their corresponding status.
 // Returns 503 if any Error status exists, 200 otherwise
 func StatusHandler(w http.ResponseWriter, r *http.Request) {
-	if r.Method == "GET" {
+	if r.Method == http.MethodGet {
 		checks := CheckStatus()
 		status := http.StatusOK
 

health/health_test.go

@@ -13,7 +13,7 @@ import (
 func TestReturns200IfThereAreNoChecks(t *testing.T) {
 	recorder := httptest.NewRecorder()
 
-	req, err := http.NewRequest("GET", "https://fakeurl.com/debug/health", nil)
+	req, err := http.NewRequest(http.MethodGet, "https://fakeurl.com/debug/health", nil)
 	if err != nil {
 		t.Errorf("Failed to create request.")
 	}
@@ -30,7 +30,7 @@ func TestReturns200IfThereAreNoChecks(t *testing.T) {
 func TestReturns503IfThereAreErrorChecks(t *testing.T) {
 	recorder := httptest.NewRecorder()
 
-	req, err := http.NewRequest("GET", "https://fakeurl.com/debug/health", nil)
+	req, err := http.NewRequest(http.MethodGet, "https://fakeurl.com/debug/health", nil)
 	if err != nil {
 		t.Errorf("Failed to create request.")
 	}

notifications/http_test.go

@@ -22,7 +22,7 @@ import (
 func TestHTTPSink(t *testing.T) {
 	serverHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()
-		if r.Method != "POST" {
+		if r.Method != http.MethodPost {
 			w.WriteHeader(http.StatusMethodNotAllowed)
 			t.Fatalf("unexpected request method: %v", r.Method)
 			return

registry/api/v2/descriptors.go

@@ -381,7 +381,7 @@ var routeDescriptors = []RouteDescriptor{
 		Description: `Base V2 API route. Typically, this can be used for lightweight version checks and to validate registry authentication.`,
 		Methods: []MethodDescriptor{
 			{
-				Method:      "GET",
+				Method:      http.MethodGet,
 				Description: "Check that the endpoint implements Docker Registry API V2.",
 				Requests: []RequestDescriptor{
 					{
@@ -415,7 +415,7 @@ var routeDescriptors = []RouteDescriptor{
 		Description: "Retrieve information about tags.",
 		Methods: []MethodDescriptor{
 			{
-				Method:      "GET",
+				Method:      http.MethodGet,
 				Description: "Fetch the tags under the repository identified by `name`.",
 				Requests: []RequestDescriptor{
 					{
@@ -519,7 +519,7 @@ var routeDescriptors = []RouteDescriptor{
 		Description: "Create, update, delete and retrieve manifests.",
 		Methods: []MethodDescriptor{
 			{
-				Method:      "GET",
+				Method:      http.MethodGet,
 				Description: "Fetch the manifest identified by `name` and `reference` where `reference` can be a tag or digest. A `HEAD` request can also be issued to this endpoint to obtain resource information without receiving all data.",
 				Requests: []RequestDescriptor{
 					{
@@ -566,7 +566,7 @@ var routeDescriptors = []RouteDescriptor{
 				},
 			},
 			{
-				Method:      "PUT",
+				Method:      http.MethodPut,
 				Description: "Put the manifest identified by `name` and `reference` where `reference` can be a tag or digest.",
 				Requests: []RequestDescriptor{
 					{
@@ -654,7 +654,7 @@ var routeDescriptors = []RouteDescriptor{
 				},
 			},
 			{
-				Method:      "DELETE",
+				Method:      http.MethodDelete,
 				Description: "Delete the manifest or tag identified by `name` and `reference` where `reference` can be a tag or digest. Note that a manifest can _only_ be deleted by digest.",
 				Requests: []RequestDescriptor{
 					{
@@ -724,7 +724,7 @@ var routeDescriptors = []RouteDescriptor{
 		Description: "Operations on blobs identified by `name` and `digest`. Used to fetch or delete layers by digest.",
 		Methods: []MethodDescriptor{
 			{
-				Method:      "GET",
+				Method:      http.MethodGet,
 				Description: "Retrieve the blob from the registry identified by `digest`. A `HEAD` request can also be issued to this endpoint to obtain resource information without receiving all data.",
 				Requests: []RequestDescriptor{
 					{
@@ -878,7 +878,7 @@ var routeDescriptors = []RouteDescriptor{
 				},
 			},
 			{
-				Method:      "DELETE",
+				Method:      http.MethodDelete,
 				Description: "Delete the blob identified by `name` and `digest`",
 				Requests: []RequestDescriptor{
 					{
@@ -958,7 +958,7 @@ var routeDescriptors = []RouteDescriptor{
 		Description: "Initiate a blob upload. This endpoint can be used to create resumable uploads or monolithic uploads.",
 		Methods: []MethodDescriptor{
 			{
-				Method:      "POST",
+				Method:      http.MethodPost,
 				Description: "Initiate a resumable blob upload. If successful, an upload location will be provided to complete the upload. Optionally, if the `digest` parameter is present, the request body will be used to complete the upload in a single request.",
 				Requests: []RequestDescriptor{
 					{
@@ -1151,7 +1151,7 @@ var routeDescriptors = []RouteDescriptor{
 		Description: "Interact with blob uploads. Clients should never assemble URLs for this endpoint and should only take it through the `Location` header on related API requests. The `Location` header and its parameters should be preserved by clients, using the latest value returned via upload related API calls.",
 		Methods: []MethodDescriptor{
 			{
-				Method:      "GET",
+				Method:      http.MethodGet,
 				Description: "Retrieve status of upload identified by `uuid`. The primary purpose of this endpoint is to resolve the current status of a resumable upload.",
 				Requests: []RequestDescriptor{
 					{
@@ -1215,7 +1215,7 @@ var routeDescriptors = []RouteDescriptor{
 				},
 			},
 			{
-				Method:      "PATCH",
+				Method:      http.MethodPatch,
 				Description: "Upload a chunk of data for the specified upload.",
 				Requests: []RequestDescriptor{
 					{
@@ -1376,7 +1376,7 @@ var routeDescriptors = []RouteDescriptor{
 				},
 			},
 			{
-				Method:      "PUT",
+				Method:      http.MethodPut,
 				Description: "Complete the upload specified by `uuid`, optionally appending the body as the final chunk.",
 				Requests: []RequestDescriptor{
 					{
@@ -1467,7 +1467,7 @@ var routeDescriptors = []RouteDescriptor{
 				},
 			},
 			{
-				Method:      "DELETE",
+				Method:      http.MethodDelete,
 				Description: "Cancel outstanding upload processes, releasing associated resources. If this is not called, the unfinished uploads will eventually timeout.",
 				Requests: []RequestDescriptor{
 					{
@@ -1532,7 +1532,7 @@ var routeDescriptors = []RouteDescriptor{
 		Description: "List a set of available repositories in the local registry cluster. Does not provide any indication of what may be available upstream. Applications can only determine if a repository is available but not if it is not available.",
 		Methods: []MethodDescriptor{
 			{
-				Method:      "GET",
+				Method:      http.MethodGet,
 				Description: "Retrieve a sorted, json list of repositories available in the registry.",
 				Requests: []RequestDescriptor{
 					{

registry/auth/htpasswd/access_test.go

@@ -74,7 +74,7 @@ func TestBasicAccessController(t *testing.T) {
 		CheckRedirect: nil,
 	}
 
-	req, _ := http.NewRequest("GET", server.URL, nil)
+	req, _ := http.NewRequest(http.MethodGet, server.URL, nil)
 	resp, err := client.Do(req)
 
 	if err != nil {
@@ -94,7 +94,7 @@ func TestBasicAccessController(t *testing.T) {
 
 	for i := 0; i < len(testUsers); i++ {
 		userNumber = i
-		req, err := http.NewRequest("GET", server.URL, nil)
+		req, err := http.NewRequest(http.MethodGet, server.URL, nil)
 		if err != nil {
 			t.Fatalf("error allocating new request: %v", err)
 		}

registry/auth/silly/access_test.go

@@ -52,7 +52,7 @@ func TestSillyAccessController(t *testing.T) {
 		t.Fatalf("unexpected response status: %v != %v", resp.StatusCode, http.StatusUnauthorized)
 	}
 
-	req, err := http.NewRequest("GET", server.URL, nil)
+	req, err := http.NewRequest(http.MethodGet, server.URL, nil)
 	if err != nil {
 		t.Fatalf("unexpected error creating new request: %v", err)
 	}

registry/auth/token/token_test.go

@@ -342,7 +342,7 @@ func TestAccessController(t *testing.T) {
 	}
 
 	// 1. Make a mock http.Request with no token.
-	req, err := http.NewRequest("GET", "http://example.com/foo", nil)
+	req, err := http.NewRequest(http.MethodGet, "http://example.com/foo", nil)
 	if err != nil {
 		t.Fatal(err)
 	}

registry/client/auth/session_test.go

@@ -109,7 +109,7 @@ func TestEndpointAuthorizeToken(t *testing.T) {
 	tokenMap := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  fmt.Sprintf("/token?scope=%s&service=%s", url.QueryEscape(scope1), service),
 			},
 			Response: testutil.Response{
@@ -119,7 +119,7 @@ func TestEndpointAuthorizeToken(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  fmt.Sprintf("/token?scope=%s&service=%s", url.QueryEscape(scope2), service),
 			},
 			Response: testutil.Response{
@@ -134,7 +134,7 @@ func TestEndpointAuthorizeToken(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -164,7 +164,7 @@ func TestEndpointAuthorizeToken(t *testing.T) {
 	transport1 := transport.NewTransport(nil, NewAuthorizer(challengeManager1, NewTokenHandler(nil, nil, repo1, "pull", "push")))
 	client := &http.Client{Transport: transport1}
 
-	req, _ := http.NewRequest("GET", e+"/v2/hello", nil)
+	req, _ := http.NewRequest(http.MethodGet, e+"/v2/hello", nil)
 	resp, err := client.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -197,7 +197,7 @@ func TestEndpointAuthorizeToken(t *testing.T) {
 	transport2 := transport.NewTransport(nil, NewAuthorizer(challengeManager2, NewTokenHandler(nil, nil, repo2, "pull", "push")))
 	client2 := &http.Client{Transport: transport2}
 
-	req, _ = http.NewRequest("GET", e2+"/v2/hello", nil)
+	req, _ = http.NewRequest(http.MethodGet, e2+"/v2/hello", nil)
 	resp, err = client2.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -219,7 +219,7 @@ func TestEndpointAuthorizeRefreshToken(t *testing.T) {
 	tokenMap := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "POST",
+				Method: http.MethodPost,
 				Route:  "/token",
 				Body:   []byte(fmt.Sprintf("client_id=registry-client&grant_type=refresh_token&refresh_token=%s&scope=%s&service=%s", refreshToken1, url.QueryEscape(scope1), service)),
 			},
@@ -231,7 +231,7 @@ func TestEndpointAuthorizeRefreshToken(t *testing.T) {
 		{
 			// In the future this test may fail and require using basic auth to get a different refresh token
 			Request: testutil.Request{
-				Method: "POST",
+				Method: http.MethodPost,
 				Route:  "/token",
 				Body:   []byte(fmt.Sprintf("client_id=registry-client&grant_type=refresh_token&refresh_token=%s&scope=%s&service=%s", refreshToken1, url.QueryEscape(scope2), service)),
 			},
@@ -242,7 +242,7 @@ func TestEndpointAuthorizeRefreshToken(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "POST",
+				Method: http.MethodPost,
 				Route:  "/token",
 				Body:   []byte(fmt.Sprintf("client_id=registry-client&grant_type=refresh_token&refresh_token=%s&scope=%s&service=%s", refreshToken2, url.QueryEscape(scope2), service)),
 			},
@@ -258,7 +258,7 @@ func TestEndpointAuthorizeRefreshToken(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -293,7 +293,7 @@ func TestEndpointAuthorizeRefreshToken(t *testing.T) {
 	transport1 := transport.NewTransport(nil, NewAuthorizer(challengeManager1, NewTokenHandler(nil, creds, repo1, "pull", "push")))
 	client := &http.Client{Transport: transport1}
 
-	req, _ := http.NewRequest("GET", e+"/v2/hello", nil)
+	req, _ := http.NewRequest(http.MethodGet, e+"/v2/hello", nil)
 	resp, err := client.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -322,7 +322,7 @@ func TestEndpointAuthorizeRefreshToken(t *testing.T) {
 	transport2 := transport.NewTransport(nil, NewAuthorizer(challengeManager2, NewTokenHandler(nil, creds, repo2, "pull", "push")))
 	client2 := &http.Client{Transport: transport2}
 
-	req, _ = http.NewRequest("GET", e2+"/v2/hello", nil)
+	req, _ = http.NewRequest(http.MethodGet, e2+"/v2/hello", nil)
 	resp, err = client2.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -352,7 +352,7 @@ func TestEndpointAuthorizeRefreshToken(t *testing.T) {
 	transport3 := transport.NewTransport(nil, NewAuthorizer(challengeManager3, NewTokenHandler(nil, creds, repo2, "pull", "push")))
 	client3 := &http.Client{Transport: transport3}
 
-	req, _ = http.NewRequest("GET", e3+"/v2/hello", nil)
+	req, _ = http.NewRequest(http.MethodGet, e3+"/v2/hello", nil)
 	resp, err = client3.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -370,7 +370,7 @@ func TestEndpointAuthorizeV2RefreshToken(t *testing.T) {
 	tokenMap := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "POST",
+				Method: http.MethodPost,
 				Route:  "/token",
 				Body:   []byte(fmt.Sprintf("client_id=registry-client&grant_type=refresh_token&refresh_token=%s&scope=%s&service=%s", refreshToken1, url.QueryEscape(scope1), service)),
 			},
@@ -386,7 +386,7 @@ func TestEndpointAuthorizeV2RefreshToken(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v1/search",
 			},
 			Response: testutil.Response{
@@ -430,7 +430,7 @@ func TestEndpointAuthorizeV2RefreshToken(t *testing.T) {
 	transport1 := transport.NewTransport(nil, NewAuthorizer(challengeManager1, NewTokenHandlerWithOptions(tho)))
 	client := &http.Client{Transport: transport1}
 
-	req, _ := http.NewRequest("GET", e+"/v1/search", nil)
+	req, _ := http.NewRequest(http.MethodGet, e+"/v1/search", nil)
 	resp, err := client.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -456,7 +456,7 @@ func TestEndpointAuthorizeTokenBasic(t *testing.T) {
 	tokenMap := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  fmt.Sprintf("/token?account=%s&scope=%s&service=%s", username, url.QueryEscape(scope), service),
 			},
 			Response: testutil.Response{
@@ -476,7 +476,7 @@ func TestEndpointAuthorizeTokenBasic(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -505,7 +505,7 @@ func TestEndpointAuthorizeTokenBasic(t *testing.T) {
 	transport1 := transport.NewTransport(nil, NewAuthorizer(challengeManager, NewTokenHandler(nil, creds, repo, "pull", "push"), NewBasicHandler(creds)))
 	client := &http.Client{Transport: transport1}
 
-	req, _ := http.NewRequest("GET", e+"/v2/hello", nil)
+	req, _ := http.NewRequest(http.MethodGet, e+"/v2/hello", nil)
 	resp, err := client.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -526,7 +526,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 	tokenMap := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  fmt.Sprintf("/token?account=%s&scope=%s&service=%s", username, url.QueryEscape(scope), service),
 			},
 			Response: testutil.Response{
@@ -536,7 +536,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  fmt.Sprintf("/token?account=%s&scope=%s&service=%s", username, url.QueryEscape(scope), service),
 			},
 			Response: testutil.Response{
@@ -558,7 +558,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -567,7 +567,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -576,7 +576,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -585,7 +585,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -594,7 +594,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -640,7 +640,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 	// Subsequent calls should recycle the token from the first request, until the expiration has lapsed.
 	timeIncrement := 1000 * time.Second
 	for i := 0; i < 4; i++ {
-		req, _ := http.NewRequest("GET", e+"/v2/hello", nil)
+		req, _ := http.NewRequest(http.MethodGet, e+"/v2/hello", nil)
 		resp, err := client.Do(req)
 		if err != nil {
 			t.Fatalf("Error sending get request: %s", err)
@@ -655,7 +655,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresIn(t *testing.T) {
 	}
 
 	// After we've exceeded the expiration, we should see a second token exchange.
-	req, _ := http.NewRequest("GET", e+"/v2/hello", nil)
+	req, _ := http.NewRequest(http.MethodGet, e+"/v2/hello", nil)
 	resp, err := client.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -686,7 +686,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresInAndIssuedAt(t *testing.T) {
 	tokenMap := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  fmt.Sprintf("/token?account=%s&scope=%s&service=%s", username, url.QueryEscape(scope), service),
 			},
 			Response: testutil.Response{
@@ -696,7 +696,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresInAndIssuedAt(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  fmt.Sprintf("/token?account=%s&scope=%s&service=%s", username, url.QueryEscape(scope), service),
 			},
 			Response: testutil.Response{
@@ -718,7 +718,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresInAndIssuedAt(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -727,7 +727,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresInAndIssuedAt(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -736,7 +736,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresInAndIssuedAt(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -745,7 +745,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresInAndIssuedAt(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -792,7 +792,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresInAndIssuedAt(t *testing.T) {
 	// We shaved one increment off of the equivalent logic in TestEndpointAuthorizeTokenBasicWithExpiresIn
 	// so this loop should have one fewer iteration.
 	for i := 0; i < 3; i++ {
-		req, _ := http.NewRequest("GET", e+"/v2/hello", nil)
+		req, _ := http.NewRequest(http.MethodGet, e+"/v2/hello", nil)
 		resp, err := client.Do(req)
 		if err != nil {
 			t.Fatalf("Error sending get request: %s", err)
@@ -807,7 +807,7 @@ func TestEndpointAuthorizeTokenBasicWithExpiresInAndIssuedAt(t *testing.T) {
 	}
 
 	// After we've exceeded the expiration, we should see a second token exchange.
-	req, _ := http.NewRequest("GET", e+"/v2/hello", nil)
+	req, _ := http.NewRequest(http.MethodGet, e+"/v2/hello", nil)
 	resp, err := client.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)
@@ -824,7 +824,7 @@ func TestEndpointAuthorizeBasic(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/hello",
 			},
 			Response: testutil.Response{
@@ -854,7 +854,7 @@ func TestEndpointAuthorizeBasic(t *testing.T) {
 	transport1 := transport.NewTransport(nil, NewAuthorizer(challengeManager, NewBasicHandler(creds)))
 	client := &http.Client{Transport: transport1}
 
-	req, _ := http.NewRequest("GET", e+"/v2/hello", nil)
+	req, _ := http.NewRequest(http.MethodGet, e+"/v2/hello", nil)
 	resp, err := client.Do(req)
 	if err != nil {
 		t.Fatalf("Error sending get request: %s", err)

registry/client/blob_writer.go

@@ -38,7 +38,7 @@ func (hbu *httpBlobUpload) handleErrorResponse(resp *http.Response) error {
 }
 
 func (hbu *httpBlobUpload) ReadFrom(r io.Reader) (n int64, err error) {
-	req, err := http.NewRequestWithContext(hbu.ctx, "PATCH", hbu.location, ioutil.NopCloser(r))
+	req, err := http.NewRequestWithContext(hbu.ctx, http.MethodPatch, hbu.location, ioutil.NopCloser(r))
 	if err != nil {
 		return 0, err
 	}
@@ -71,7 +71,7 @@ func (hbu *httpBlobUpload) ReadFrom(r io.Reader) (n int64, err error) {
 }
 
 func (hbu *httpBlobUpload) Write(p []byte) (n int, err error) {
-	req, err := http.NewRequestWithContext(hbu.ctx, "PATCH", hbu.location, bytes.NewReader(p))
+	req, err := http.NewRequestWithContext(hbu.ctx, http.MethodPatch, hbu.location, bytes.NewReader(p))
 	if err != nil {
 		return 0, err
 	}
@@ -119,7 +119,7 @@ func (hbu *httpBlobUpload) StartedAt() time.Time {
 
 func (hbu *httpBlobUpload) Commit(ctx context.Context, desc distribution.Descriptor) (distribution.Descriptor, error) {
 	// TODO(dmcgowan): Check if already finished, if so just fetch
-	req, err := http.NewRequestWithContext(hbu.ctx, "PUT", hbu.location, nil)
+	req, err := http.NewRequestWithContext(hbu.ctx, http.MethodPut, hbu.location, nil)
 	if err != nil {
 		return distribution.Descriptor{}, err
 	}
@@ -142,7 +142,7 @@ func (hbu *httpBlobUpload) Commit(ctx context.Context, desc distribution.Descrip
 }
 
 func (hbu *httpBlobUpload) Cancel(ctx context.Context) error {
-	req, err := http.NewRequestWithContext(hbu.ctx, "DELETE", hbu.location, nil)
+	req, err := http.NewRequestWithContext(hbu.ctx, http.MethodDelete, hbu.location, nil)
 	if err != nil {
 		return err
 	}

registry/client/blob_writer_test.go

@@ -24,7 +24,7 @@ func TestUploadReadFrom(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/",
 			},
 			Response: testutil.Response{
@@ -37,7 +37,7 @@ func TestUploadReadFrom(t *testing.T) {
 		// Test Valid case
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -53,7 +53,7 @@ func TestUploadReadFrom(t *testing.T) {
 		// Test invalid range
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -69,7 +69,7 @@ func TestUploadReadFrom(t *testing.T) {
 		// Test 404
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -80,7 +80,7 @@ func TestUploadReadFrom(t *testing.T) {
 		// Test 400 valid json
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -101,7 +101,7 @@ func TestUploadReadFrom(t *testing.T) {
 		// Test 400 invalid json
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -113,7 +113,7 @@ func TestUploadReadFrom(t *testing.T) {
 		// Test 500
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -220,7 +220,7 @@ func TestUploadSize(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/",
 			},
 			Response: testutil.Response{
@@ -232,7 +232,7 @@ func TestUploadSize(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  readFromLocationPath,
 				Body:   b,
 			},
@@ -247,7 +247,7 @@ func TestUploadSize(t *testing.T) {
 		},
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  writeLocationPath,
 				Body:   b,
 			},
@@ -310,7 +310,7 @@ func TestUploadWrite(t *testing.T) {
 	m := testutil.RequestResponseMap([]testutil.RequestResponseMapping{
 		{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/",
 			},
 			Response: testutil.Response{
@@ -323,7 +323,7 @@ func TestUploadWrite(t *testing.T) {
 		// Test Valid case
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -339,7 +339,7 @@ func TestUploadWrite(t *testing.T) {
 		// Test invalid range
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -355,7 +355,7 @@ func TestUploadWrite(t *testing.T) {
 		// Test 404
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -366,7 +366,7 @@ func TestUploadWrite(t *testing.T) {
 		// Test 400 valid json
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -387,7 +387,7 @@ func TestUploadWrite(t *testing.T) {
 		// Test 400 invalid json
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},
@@ -399,7 +399,7 @@ func TestUploadWrite(t *testing.T) {
 		// Test 500
 		{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  locationPath,
 				Body:   b,
 			},

registry/client/repository.go

@@ -98,7 +98,7 @@ func (r *registry) Repositories(ctx context.Context, entries []string, last stri
 		return 0, err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "GET", u, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u, nil)
 	if err != nil {
 		return 0, err
 	}
@@ -216,7 +216,7 @@ func (t *tags) All(ctx context.Context) ([]string, error) {
 	}
 
 	for {
-		req, err := http.NewRequestWithContext(ctx, "GET", listURL.String(), nil)
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, listURL.String(), nil)
 		if err != nil {
 			return nil, err
 		}
@@ -268,11 +268,11 @@ func descriptorFromResponse(response *http.Response) (distribution.Descriptor, e
 
 	digestHeader := headers.Get("Docker-Content-Digest")
 	if digestHeader == "" {
-		bytes, err := ioutil.ReadAll(response.Body)
+		data, err := ioutil.ReadAll(response.Body)
 		if err != nil {
 			return distribution.Descriptor{}, err
 		}
-		_, desc, err := distribution.UnmarshalManifest(ctHeader, bytes)
+		_, desc, err := distribution.UnmarshalManifest(ctHeader, data)
 		if err != nil {
 			return distribution.Descriptor{}, err
 		}
@@ -325,7 +325,7 @@ func (t *tags) Get(ctx context.Context, tag string) (distribution.Descriptor, er
 		return resp, err
 	}
 
-	resp, err := newRequest("HEAD")
+	resp, err := newRequest(http.MethodHead)
 	if err != nil {
 		return distribution.Descriptor{}, err
 	}
@@ -340,7 +340,7 @@ func (t *tags) Get(ctx context.Context, tag string) (distribution.Descriptor, er
 		// Issue a GET request:
 		//   - for data from a server that does not handle HEAD
 		//   - to get error details in case of a failure
-		resp, err = newRequest("GET")
+		resp, err = newRequest(http.MethodGet)
 		if err != nil {
 			return distribution.Descriptor{}, err
 		}
@@ -371,7 +371,7 @@ func (t *tags) Untag(ctx context.Context, tag string) error {
 		return err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "DELETE", u, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodDelete, u, nil)
 	if err != nil {
 		return err
 	}
@@ -405,7 +405,7 @@ func (ms *manifests) Exists(ctx context.Context, dgst digest.Digest) (bool, erro
 		return false, err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "HEAD", u, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodHead, u, nil)
 	if err != nil {
 		return false, err
 	}
@@ -500,7 +500,7 @@ func (ms *manifests) Get(ctx context.Context, dgst digest.Digest, options ...dis
 		return nil, err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "GET", u, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -585,7 +585,7 @@ func (ms *manifests) Put(ctx context.Context, m distribution.Manifest, options .
 		return "", err
 	}
 
-	putRequest, err := http.NewRequestWithContext(ctx, "PUT", manifestURL, bytes.NewReader(p))
+	putRequest, err := http.NewRequestWithContext(ctx, http.MethodPut, manifestURL, bytes.NewReader(p))
 	if err != nil {
 		return "", err
 	}
@@ -620,7 +620,7 @@ func (ms *manifests) Delete(ctx context.Context, dgst digest.Digest) error {
 	if err != nil {
 		return err
 	}
-	req, err := http.NewRequestWithContext(ctx, "DELETE", u, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodDelete, u, nil)
 	if err != nil {
 		return err
 	}
@@ -790,7 +790,7 @@ func (bs *blobs) Create(ctx context.Context, options ...distribution.BlobCreateO
 		return nil, err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "POST", u, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, u, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -873,7 +873,7 @@ func (bs *blobStatter) Stat(ctx context.Context, dgst digest.Digest) (distributi
 		return distribution.Descriptor{}, err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "HEAD", u, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodHead, u, nil)
 	if err != nil {
 		return distribution.Descriptor{}, err
 	}
@@ -929,7 +929,7 @@ func (bs *blobStatter) Clear(ctx context.Context, dgst digest.Digest) error {
 		return err
 	}
 
-	req, err := http.NewRequestWithContext(ctx, "DELETE", blobURL, nil)
+	req, err := http.NewRequestWithContext(ctx, http.MethodDelete, blobURL, nil)
 	if err != nil {
 		return err
 	}

registry/client/repository_test.go

@@ -50,7 +50,7 @@ func newRandomBlob(size int) (digest.Digest, []byte) {
 func addTestFetch(repo string, dgst digest.Digest, content []byte, m *testutil.RequestResponseMap) {
 	*m = append(*m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "GET",
+			Method: http.MethodGet,
 			Route:  "/v2/" + repo + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -66,7 +66,7 @@ func addTestFetch(repo string, dgst digest.Digest, content []byte, m *testutil.R
 
 	*m = append(*m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -91,7 +91,7 @@ func addTestCatalog(route string, content []byte, link string, m *testutil.Reque
 
 	*m = append(*m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "GET",
+			Method: http.MethodGet,
 			Route:  route,
 		},
 		Response: testutil.Response{
@@ -119,7 +119,7 @@ func TestBlobServeBlob(t *testing.T) {
 	l := r.Blobs(ctx)
 
 	resp := httptest.NewRecorder()
-	req := httptest.NewRequest("GET", "/", nil)
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
 
 	err = l.ServeBlob(ctx, resp, req, dgst)
 	if err != nil {
@@ -168,7 +168,7 @@ func TestBlobServeBlobHEAD(t *testing.T) {
 	l := r.Blobs(ctx)
 
 	resp := httptest.NewRecorder()
-	req := httptest.NewRequest("HEAD", "/", nil)
+	req := httptest.NewRequest(http.MethodHead, "/", nil)
 
 	err = l.ServeBlob(ctx, resp, req, dgst)
 	if err != nil {
@@ -207,7 +207,7 @@ func TestBlobResume(t *testing.T) {
 	repo, _ := reference.WithName("test.example.com/repo1")
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PATCH",
+			Method: http.MethodPatch,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/" + id,
 			Body:   b1,
 		},
@@ -221,7 +221,7 @@ func TestBlobResume(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PUT",
+			Method: http.MethodPut,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/" + id,
 			QueryParams: map[string][]string{
 				"digest": {dgst.String()},
@@ -237,7 +237,7 @@ func TestBlobResume(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -295,7 +295,7 @@ func TestBlobDelete(t *testing.T) {
 	repo, _ := reference.WithName("test.example.com/repo1")
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "DELETE",
+			Method: http.MethodDelete,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -356,7 +356,7 @@ func TestBlobExistsNoContentLength(t *testing.T) {
 	dgst, content := newRandomBlob(1024)
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "GET",
+			Method: http.MethodGet,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -371,7 +371,7 @@ func TestBlobExistsNoContentLength(t *testing.T) {
 
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -447,7 +447,7 @@ func TestBlobUploadChunked(t *testing.T) {
 	uuids := []string{uuid.Generate().String()}
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "POST",
+			Method: http.MethodPost,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/",
 		},
 		Response: testutil.Response{
@@ -466,7 +466,7 @@ func TestBlobUploadChunked(t *testing.T) {
 		newOffset := offset + len(chunk)
 		m = append(m, testutil.RequestResponseMapping{
 			Request: testutil.Request{
-				Method: "PATCH",
+				Method: http.MethodPatch,
 				Route:  "/v2/" + repo.Name() + "/blobs/uploads/" + uuids[i],
 				Body:   chunk,
 			},
@@ -484,7 +484,7 @@ func TestBlobUploadChunked(t *testing.T) {
 	}
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PUT",
+			Method: http.MethodPut,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/" + uuids[len(uuids)-1],
 			QueryParams: map[string][]string{
 				"digest": {dgst.String()},
@@ -501,7 +501,7 @@ func TestBlobUploadChunked(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -562,7 +562,7 @@ func TestBlobUploadMonolithic(t *testing.T) {
 	uploadID := uuid.Generate().String()
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "POST",
+			Method: http.MethodPost,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/",
 		},
 		Response: testutil.Response{
@@ -577,7 +577,7 @@ func TestBlobUploadMonolithic(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PATCH",
+			Method: http.MethodPatch,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/" + uploadID,
 			Body:   b1,
 		},
@@ -594,7 +594,7 @@ func TestBlobUploadMonolithic(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PUT",
+			Method: http.MethodPut,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/" + uploadID,
 			QueryParams: map[string][]string{
 				"digest": {dgst.String()},
@@ -611,7 +611,7 @@ func TestBlobUploadMonolithic(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -670,7 +670,7 @@ func TestBlobUploadMonolithicDockerUploadUUIDFromURL(t *testing.T) {
 	uploadID := uuid.Generate().String()
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "POST",
+			Method: http.MethodPost,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/",
 		},
 		Response: testutil.Response{
@@ -684,7 +684,7 @@ func TestBlobUploadMonolithicDockerUploadUUIDFromURL(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PATCH",
+			Method: http.MethodPatch,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/" + uploadID,
 			Body:   b1,
 		},
@@ -700,7 +700,7 @@ func TestBlobUploadMonolithicDockerUploadUUIDFromURL(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PUT",
+			Method: http.MethodPut,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/" + uploadID,
 			QueryParams: map[string][]string{
 				"digest": {dgst.String()},
@@ -717,7 +717,7 @@ func TestBlobUploadMonolithicDockerUploadUUIDFromURL(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -775,7 +775,7 @@ func TestBlobUploadMonolithicNoDockerUploadUUID(t *testing.T) {
 	repo, _ := reference.WithName("test.example.com/uploadrepo")
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "POST",
+			Method: http.MethodPost,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/",
 		},
 		Response: testutil.Response{
@@ -789,7 +789,7 @@ func TestBlobUploadMonolithicNoDockerUploadUUID(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PATCH",
+			Method: http.MethodPatch,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/",
 			Body:   b1,
 		},
@@ -805,7 +805,7 @@ func TestBlobUploadMonolithicNoDockerUploadUUID(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PUT",
+			Method: http.MethodPut,
 			Route:  "/v2/" + repo.Name() + "/blobs/uploads/",
 			QueryParams: map[string][]string{
 				"digest": {dgst.String()},
@@ -822,7 +822,7 @@ func TestBlobUploadMonolithicNoDockerUploadUUID(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -865,7 +865,7 @@ func TestBlobMount(t *testing.T) {
 
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method:      "POST",
+			Method:      http.MethodPost,
 			Route:       "/v2/" + repo.Name() + "/blobs/uploads/",
 			QueryParams: map[string][]string{"from": {sourceRepo.Name()}, "mount": {dgst.String()}},
 		},
@@ -880,7 +880,7 @@ func TestBlobMount(t *testing.T) {
 	})
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/blobs/" + dgst.String(),
 		},
 		Response: testutil.Response{
@@ -958,7 +958,7 @@ func newRandomSchemaV1Manifest(name reference.Named, tag string, blobCount int)
 func addTestManifestWithEtag(repo reference.Named, reference string, content []byte, m *testutil.RequestResponseMap, dgst string) {
 	actualDigest := digest.FromBytes(content)
 	getReqWithEtag := testutil.Request{
-		Method: "GET",
+		Method: http.MethodGet,
 		Route:  "/v2/" + repo.Name() + "/manifests/" + reference,
 		Headers: http.Header(map[string][]string{
 			"If-None-Match": {fmt.Sprintf(`"%s"`, dgst)},
@@ -1002,7 +1002,7 @@ func contentDigestString(mediatype string, content []byte) string {
 func addTestManifest(repo reference.Named, reference string, mediatype string, content []byte, m *testutil.RequestResponseMap) {
 	*m = append(*m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "GET",
+			Method: http.MethodGet,
 			Route:  "/v2/" + repo.Name() + "/manifests/" + reference,
 		},
 		Response: testutil.Response{
@@ -1018,7 +1018,7 @@ func addTestManifest(repo reference.Named, reference string, mediatype string, c
 	})
 	*m = append(*m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/manifests/" + reference,
 		},
 		Response: testutil.Response{
@@ -1036,7 +1036,7 @@ func addTestManifest(repo reference.Named, reference string, mediatype string, c
 func addTestManifestWithoutDigestHeader(repo reference.Named, reference string, mediatype string, content []byte, m *testutil.RequestResponseMap) {
 	*m = append(*m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "GET",
+			Method: http.MethodGet,
 			Route:  "/v2/" + repo.Name() + "/manifests/" + reference,
 		},
 		Response: testutil.Response{
@@ -1051,7 +1051,7 @@ func addTestManifestWithoutDigestHeader(repo reference.Named, reference string,
 	})
 	*m = append(*m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "HEAD",
+			Method: http.MethodHead,
 			Route:  "/v2/" + repo.Name() + "/manifests/" + reference,
 		},
 		Response: testutil.Response{
@@ -1265,7 +1265,7 @@ func TestManifestDelete(t *testing.T) {
 	var m testutil.RequestResponseMap
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "DELETE",
+			Method: http.MethodDelete,
 			Route:  "/v2/" + repo.Name() + "/manifests/" + dgst1.String(),
 		},
 		Response: testutil.Response{
@@ -1310,7 +1310,7 @@ func TestManifestPut(t *testing.T) {
 	var m testutil.RequestResponseMap
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PUT",
+			Method: http.MethodPut,
 			Route:  "/v2/" + repo.Name() + "/manifests/other",
 			Body:   payload,
 		},
@@ -1326,7 +1326,7 @@ func TestManifestPut(t *testing.T) {
 	putDgst := digest.FromBytes(m1.Canonical)
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "PUT",
+			Method: http.MethodPut,
 			Route:  "/v2/" + repo.Name() + "/manifests/" + putDgst.String(),
 			Body:   payload,
 		},
@@ -1379,7 +1379,7 @@ func TestManifestTags(t *testing.T) {
 	for i := 0; i < 3; i++ {
 		m = append(m, testutil.RequestResponseMapping{
 			Request: testutil.Request{
-				Method: "GET",
+				Method: http.MethodGet,
 				Route:  "/v2/" + repo.Name() + "/tags/list",
 			},
 			Response: testutil.Response{
@@ -1433,7 +1433,7 @@ func TestTagDelete(t *testing.T) {
 	var m testutil.RequestResponseMap
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "DELETE",
+			Method: http.MethodDelete,
 			Route:  "/v2/" + repo.Name() + "/manifests/" + tag,
 		},
 		Response: testutil.Response{
@@ -1474,7 +1474,7 @@ func TestObtainsErrorForMissingTag(t *testing.T) {
 	}
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "GET",
+			Method: http.MethodGet,
 			Route:  "/v2/" + repo.Name() + "/manifests/1.0.0",
 		},
 		Response: testutil.Response{
@@ -1578,7 +1578,7 @@ func TestManifestTagsPaginated(t *testing.T) {
 
 		m = append(m, testutil.RequestResponseMapping{
 			Request: testutil.Request{
-				Method:      "GET",
+				Method:      http.MethodGet,
 				Route:       "/v2/" + repo.Name() + "/tags/list",
 				QueryParams: queryParams,
 			},
@@ -1628,7 +1628,7 @@ func TestManifestUnauthorized(t *testing.T) {
 
 	m = append(m, testutil.RequestResponseMapping{
 		Request: testutil.Request{
-			Method: "GET",
+			Method: http.MethodGet,
 			Route:  "/v2/" + repo.Name() + "/manifests/" + dgst.String(),
 		},
 		Response: testutil.Response{

registry/client/transport/http_reader.go

@@ -171,7 +171,7 @@ func (hrs *httpReadSeeker) reader() (io.Reader, error) {
 		return hrs.rc, nil
 	}
 
-	req, err := http.NewRequestWithContext(hrs.ctx, "GET", hrs.url, nil)
+	req, err := http.NewRequestWithContext(hrs.ctx, http.MethodGet, hrs.url, nil)
 	if err != nil {
 		return nil, err
 	}

registry/handlers/api_test.go

@@ -613,7 +613,7 @@ func testBlobAPI(t *testing.T, env *testEnv, args blobArgs) *testEnv {
 		"Docker-Upload-UUID": []string{uploadUUID},
 	})
 
-	req, err := http.NewRequest("DELETE", uploadURLBase, nil)
+	req, err := http.NewRequest(http.MethodDelete, uploadURLBase, nil)
 	if err != nil {
 		t.Fatalf("unexpected error creating delete request: %v", err)
 	}
@@ -786,7 +786,7 @@ func testBlobAPI(t *testing.T, env *testEnv, args blobArgs) *testEnv {
 
 	// Matching etag, gives 304
 	etag := resp.Header.Get("Etag")
-	req, err = http.NewRequest("GET", layerURL, nil)
+	req, err = http.NewRequest(http.MethodGet, layerURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -800,7 +800,7 @@ func testBlobAPI(t *testing.T, env *testEnv, args blobArgs) *testEnv {
 	checkResponse(t, "fetching layer with etag", resp, http.StatusNotModified)
 
 	// Non-matching etag, gives 200
-	req, err = http.NewRequest("GET", layerURL, nil)
+	req, err = http.NewRequest(http.MethodGet, layerURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -972,7 +972,7 @@ func TestStartPushReadOnly(t *testing.T) {
 }
 
 func httpDelete(url string) (*http.Response, error) {
-	req, err := http.NewRequest("DELETE", url, nil)
+	req, err := http.NewRequest(http.MethodDelete, url, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -1490,7 +1490,7 @@ func testManifestAPISchema1(t *testing.T, env *testEnv, imageName reference.Name
 
 	// Get by name with etag, gives 304
 	etag := resp.Header.Get("Etag")
-	req, err := http.NewRequest("GET", manifestURL, nil)
+	req, err := http.NewRequest(http.MethodGet, manifestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -1503,7 +1503,7 @@ func testManifestAPISchema1(t *testing.T, env *testEnv, imageName reference.Name
 	checkResponse(t, "fetching manifest by name with etag", resp, http.StatusNotModified)
 
 	// Get by digest with etag, gives 304
-	req, err = http.NewRequest("GET", manifestDigestURL, nil)
+	req, err = http.NewRequest(http.MethodGet, manifestDigestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -1732,7 +1732,7 @@ func testManifestAPISchema2(t *testing.T, env *testEnv, imageName reference.Name
 
 	// ------------------
 	// Fetch by tag name
-	req, err := http.NewRequest("GET", manifestURL, nil)
+	req, err := http.NewRequest(http.MethodGet, manifestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -1767,7 +1767,7 @@ func testManifestAPISchema2(t *testing.T, env *testEnv, imageName reference.Name
 
 	// ---------------
 	// Fetch by digest
-	req, err = http.NewRequest("GET", manifestDigestURL, nil)
+	req, err = http.NewRequest(http.MethodGet, manifestDigestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -1799,7 +1799,7 @@ func testManifestAPISchema2(t *testing.T, env *testEnv, imageName reference.Name
 
 	// Get by name with etag, gives 304
 	etag := resp.Header.Get("Etag")
-	req, err = http.NewRequest("GET", manifestURL, nil)
+	req, err = http.NewRequest(http.MethodGet, manifestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -1812,7 +1812,7 @@ func testManifestAPISchema2(t *testing.T, env *testEnv, imageName reference.Name
 	checkResponse(t, "fetching manifest by name with etag", resp, http.StatusNotModified)
 
 	// Get by digest with etag, gives 304
-	req, err = http.NewRequest("GET", manifestDigestURL, nil)
+	req, err = http.NewRequest(http.MethodGet, manifestDigestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -1992,7 +1992,7 @@ func testManifestAPIManifestList(t *testing.T, env *testEnv, args manifestArgs)
 
 	// ------------------
 	// Fetch by tag name
-	req, err := http.NewRequest("GET", manifestURL, nil)
+	req, err := http.NewRequest(http.MethodGet, manifestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -2029,7 +2029,7 @@ func testManifestAPIManifestList(t *testing.T, env *testEnv, args manifestArgs)
 
 	// ---------------
 	// Fetch by digest
-	req, err = http.NewRequest("GET", manifestDigestURL, nil)
+	req, err = http.NewRequest(http.MethodGet, manifestDigestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -2061,7 +2061,7 @@ func testManifestAPIManifestList(t *testing.T, env *testEnv, args manifestArgs)
 
 	// Get by name with etag, gives 304
 	etag := resp.Header.Get("Etag")
-	req, err = http.NewRequest("GET", manifestURL, nil)
+	req, err = http.NewRequest(http.MethodGet, manifestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -2074,7 +2074,7 @@ func testManifestAPIManifestList(t *testing.T, env *testEnv, args manifestArgs)
 	checkResponse(t, "fetching manifest by name with etag", resp, http.StatusNotModified)
 
 	// Get by digest with etag, gives 304
-	req, err = http.NewRequest("GET", manifestDigestURL, nil)
+	req, err = http.NewRequest(http.MethodGet, manifestDigestURL, nil)
 	if err != nil {
 		t.Fatalf("Error constructing request: %s", err)
 	}
@@ -2383,7 +2383,7 @@ func putManifest(t *testing.T, msg, url, contentType string, v interface{}) *htt
 		}
 	}
 
-	req, err := http.NewRequest("PUT", url, bytes.NewReader(body))
+	req, err := http.NewRequest(http.MethodPut, url, bytes.NewReader(body))
 	if err != nil {
 		t.Fatalf("error creating request for %s: %v", msg, err)
 	}
@@ -2457,7 +2457,7 @@ func doPushLayer(t *testing.T, ub *v2.URLBuilder, name reference.Named, dgst dig
 	uploadURL := u.String()
 
 	// Just do a monolithic upload
-	req, err := http.NewRequest("PUT", uploadURL, body)
+	req, err := http.NewRequest(http.MethodPut, uploadURL, body)
 	if err != nil {
 		t.Fatalf("unexpected error creating new request: %v", err)
 	}
@@ -2560,7 +2560,7 @@ func doPushChunk(t *testing.T, uploadURLBase string, body io.Reader, options chu
 
 	uploadURL := u.String()
 
-	req, err := http.NewRequest("PATCH", uploadURL, body)
+	req, err := http.NewRequest(http.MethodPatch, uploadURL, body)
 	if err != nil {
 		t.Fatalf("unexpected error creating new request: %v", err)
 	}

registry/handlers/app.go

@@ -838,7 +838,7 @@ func (app *App) authorized(w http.ResponseWriter, r *http.Request, context *Cont
 		if fromRepo := r.FormValue("from"); fromRepo != "" {
 			// mounting a blob from one repository to another requires pull (GET)
 			// access to the source repository.
-			accessRecords = appendAccessRecords(accessRecords, "GET", fromRepo)
+			accessRecords = appendAccessRecords(accessRecords, http.MethodGet, fromRepo)
 		}
 	} else {
 		// Only allow the name not to be set on the base route.
@@ -927,13 +927,13 @@ func appendAccessRecords(records []auth.Access, method string, repo string) []au
 	}
 
 	switch method {
-	case "GET", "HEAD":
+	case http.MethodGet, http.MethodHead:
 		records = append(records,
 			auth.Access{
 				Resource: resource,
 				Action:   "pull",
 			})
-	case "POST", "PUT", "PATCH":
+	case http.MethodPost, http.MethodPut, http.MethodPatch:
 		records = append(records,
 			auth.Access{
 				Resource: resource,
@@ -943,7 +943,7 @@ func appendAccessRecords(records []auth.Access, method string, repo string) []au
 				Resource: resource,
 				Action:   "push",
 			})
-	case "DELETE":
+	case http.MethodDelete:
 		records = append(records,
 			auth.Access{
 				Resource: resource,

registry/handlers/app_test.go

@@ -235,42 +235,42 @@ func TestAppendAccessRecords(t *testing.T) {
 	}
 
 	records := []auth.Access{}
-	result := appendAccessRecords(records, "GET", repo)
+	result := appendAccessRecords(records, http.MethodGet, repo)
 	expectedResult := []auth.Access{expectedPullRecord}
 	if ok := reflect.DeepEqual(result, expectedResult); !ok {
 		t.Fatalf("Actual access record differs from expected")
 	}
 
 	records = []auth.Access{}
-	result = appendAccessRecords(records, "HEAD", repo)
+	result = appendAccessRecords(records, http.MethodHead, repo)
 	expectedResult = []auth.Access{expectedPullRecord}
 	if ok := reflect.DeepEqual(result, expectedResult); !ok {
 		t.Fatalf("Actual access record differs from expected")
 	}
 
 	records = []auth.Access{}
-	result = appendAccessRecords(records, "POST", repo)
+	result = appendAccessRecords(records, http.MethodPost, repo)
 	expectedResult = []auth.Access{expectedPullRecord, expectedPushRecord}
 	if ok := reflect.DeepEqual(result, expectedResult); !ok {
 		t.Fatalf("Actual access record differs from expected")
 	}
 
 	records = []auth.Access{}
-	result = appendAccessRecords(records, "PUT", repo)
+	result = appendAccessRecords(records, http.MethodPut, repo)
 	expectedResult = []auth.Access{expectedPullRecord, expectedPushRecord}
 	if ok := reflect.DeepEqual(result, expectedResult); !ok {
 		t.Fatalf("Actual access record differs from expected")
 	}
 
 	records = []auth.Access{}
-	result = appendAccessRecords(records, "PATCH", repo)
+	result = appendAccessRecords(records, http.MethodPatch, repo)
 	expectedResult = []auth.Access{expectedPullRecord, expectedPushRecord}
 	if ok := reflect.DeepEqual(result, expectedResult); !ok {
 		t.Fatalf("Actual access record differs from expected")
 	}
 
 	records = []auth.Access{}
-	result = appendAccessRecords(records, "DELETE", repo)
+	result = appendAccessRecords(records, http.MethodDelete, repo)
 	expectedResult = []auth.Access{expectedDeleteRecord}
 	if ok := reflect.DeepEqual(result, expectedResult); !ok {
 		t.Fatalf("Actual access record differs from expected")

registry/handlers/blob.go

@@ -33,12 +33,12 @@ func blobDispatcher(ctx *Context, r *http.Request) http.Handler {
 	}
 
 	mhandler := handlers.MethodHandler{
-		"GET":  http.HandlerFunc(blobHandler.GetBlob),
+		http.MethodGet:  http.HandlerFunc(blobHandler.GetBlob),
-		"HEAD": http.HandlerFunc(blobHandler.GetBlob),
+		http.MethodHead: http.HandlerFunc(blobHandler.GetBlob),
 	}
 
 	if !ctx.readOnly {
-		mhandler["DELETE"] = http.HandlerFunc(blobHandler.DeleteBlob)
+		mhandler[http.MethodDelete] = http.HandlerFunc(blobHandler.DeleteBlob)
 	}
 
 	return mhandler

registry/handlers/blobupload.go

@@ -25,15 +25,15 @@ func blobUploadDispatcher(ctx *Context, r *http.Request) http.Handler {
 	}
 
 	handler := handlers.MethodHandler{
-		"GET":  http.HandlerFunc(buh.GetUploadStatus),
+		http.MethodGet:  http.HandlerFunc(buh.GetUploadStatus),
-		"HEAD": http.HandlerFunc(buh.GetUploadStatus),
+		http.MethodHead: http.HandlerFunc(buh.GetUploadStatus),
 	}
 
 	if !ctx.readOnly {
-		handler["POST"] = http.HandlerFunc(buh.StartBlobUpload)
+		handler[http.MethodPost] = http.HandlerFunc(buh.StartBlobUpload)
-		handler["PATCH"] = http.HandlerFunc(buh.PatchBlobData)
+		handler[http.MethodPatch] = http.HandlerFunc(buh.PatchBlobData)
-		handler["PUT"] = http.HandlerFunc(buh.PutBlobUploadComplete)
+		handler[http.MethodPut] = http.HandlerFunc(buh.PutBlobUploadComplete)
-		handler["DELETE"] = http.HandlerFunc(buh.CancelBlobUpload)
+		handler[http.MethodDelete] = http.HandlerFunc(buh.CancelBlobUpload)
 	}
 
 	if buh.UUID != "" {

registry/handlers/catalog.go

@@ -21,7 +21,7 @@ func catalogDispatcher(ctx *Context, r *http.Request) http.Handler {
 	}
 
 	return handlers.MethodHandler{
-		"GET": http.HandlerFunc(catalogHandler.GetCatalog),
+		http.MethodGet: http.HandlerFunc(catalogHandler.GetCatalog),
 	}
 }
 

registry/handlers/health_test.go

@@ -137,7 +137,7 @@ func TestHTTPHealthCheck(t *testing.T) {
 	stopFailing := make(chan struct{})
 
 	checkedServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if r.Method != "HEAD" {
+		if r.Method != http.MethodHead {
 			t.Fatalf("expected HEAD request, got %s", r.Method)
 		}
 		select {

registry/handlers/manifests.go

@@ -49,23 +49,23 @@ func manifestDispatcher(ctx *Context, r *http.Request) http.Handler {
 	manifestHandler := &manifestHandler{
 		Context: ctx,
 	}
-	reference := getReference(ctx)
+	ref := getReference(ctx)
-	dgst, err := digest.Parse(reference)
+	dgst, err := digest.Parse(ref)
 	if err != nil {
 		// We just have a tag
-		manifestHandler.Tag = reference
+		manifestHandler.Tag = ref
 	} else {
 		manifestHandler.Digest = dgst
 	}
 
 	mhandler := handlers.MethodHandler{
-		"GET":  http.HandlerFunc(manifestHandler.GetManifest),
+		http.MethodGet:  http.HandlerFunc(manifestHandler.GetManifest),
-		"HEAD": http.HandlerFunc(manifestHandler.GetManifest),
+		http.MethodHead: http.HandlerFunc(manifestHandler.GetManifest),
 	}
 
 	if !ctx.readOnly {
-		mhandler["PUT"] = http.HandlerFunc(manifestHandler.PutManifest)
+		mhandler[http.MethodPut] = http.HandlerFunc(manifestHandler.PutManifest)
-		mhandler["DELETE"] = http.HandlerFunc(manifestHandler.DeleteManifest)
+		mhandler[http.MethodDelete] = http.HandlerFunc(manifestHandler.DeleteManifest)
 	}
 
 	return mhandler

registry/handlers/tags.go

@@ -19,7 +19,7 @@ func tagsDispatcher(ctx *Context, r *http.Request) http.Handler {
 	}
 
 	return handlers.MethodHandler{
-		"GET": http.HandlerFunc(tagsHandler.GetTags),
+		http.MethodGet: http.HandlerFunc(tagsHandler.GetTags),
 	}
 }
 

registry/proxy/proxyblobstore_test.go

@@ -337,7 +337,7 @@ func testProxyStoreServe(t *testing.T, te *testEnv, numClients int) {
 			defer wg.Done()
 			for _, remoteBlob := range te.inRemote {
 				w := httptest.NewRecorder()
-				r, err := http.NewRequest("GET", "", nil)
+				r, err := http.NewRequest(http.MethodGet, "", nil)
 				if err != nil {
 					t.Error(err)
 					return
@@ -383,7 +383,7 @@ func testProxyStoreServe(t *testing.T, te *testEnv, numClients int) {
 	// Serveblob - blobs come from local
 	for _, dr := range te.inRemote {
 		w := httptest.NewRecorder()
-		r, err := http.NewRequest("GET", "", nil)
+		r, err := http.NewRequest(http.MethodGet, "", nil)
 		if err != nil {
 			t.Fatal(err)
 		}

registry/storage/driver/gcs/gcs.go

@@ -321,7 +321,7 @@ func getObject(client *http.Client, bucket string, name string, offset int64) (*
 		Host:   "storage.googleapis.com",
 		Path:   fmt.Sprintf("/%s/%s", bucket, name),
 	}
-	req, err := http.NewRequest("GET", u.String(), nil)
+	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
 	if err != nil {
 		return nil, err
 	}
@@ -808,11 +808,11 @@ func (d *driver) URLFor(context context.Context, path string, options map[string
 	}
 
 	name := d.pathToKey(path)
-	methodString := "GET"
+	methodString := http.MethodGet
 	method, ok := options["method"]
 	if ok {
 		methodString, ok = method.(string)
-		if !ok || (methodString != "GET" && methodString != "HEAD") {
+		if !ok || (methodString != http.MethodGet && methodString != http.MethodHead) {
 			return "", storagedriver.ErrUnsupportedMethod{}
 		}
 	}
@@ -849,7 +849,7 @@ func startSession(client *http.Client, bucket string, name string) (uri string,
 		RawQuery: fmt.Sprintf("uploadType=resumable&name=%v", name),
 	}
 	err = retry(func() error {
-		req, err := http.NewRequest("POST", u.String(), nil)
+		req, err := http.NewRequest(http.MethodPost, u.String(), nil)
 		if err != nil {
 			return err
 		}
@@ -873,7 +873,7 @@ func startSession(client *http.Client, bucket string, name string) (uri string,
 func putChunk(client *http.Client, sessionURI string, chunk []byte, from int64, totalSize int64) (int64, error) {
 	bytesPut := int64(0)
 	err := retry(func() error {
-		req, err := http.NewRequest("PUT", sessionURI, bytes.NewReader(chunk))
+		req, err := http.NewRequest(http.MethodPut, sessionURI, bytes.NewReader(chunk))
 		if err != nil {
 			return err
 		}

registry/storage/driver/oss/oss.go

@@ -465,11 +465,11 @@ func (d *driver) Delete(ctx context.Context, path string) error {
 // URLFor returns a URL which may be used to retrieve the content stored at the given path.
 // May return an UnsupportedMethodErr in certain StorageDriver implementations.
 func (d *driver) URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error) {
-	methodString := "GET"
+	methodString := http.MethodGet
 	method, ok := options["method"]
 	if ok {
 		methodString, ok = method.(string)
-		if !ok || (methodString != "GET") {
+		if !ok || (methodString != http.MethodGet) {
 			return "", storagedriver.ErrUnsupportedMethod{}
 		}
 	}

registry/storage/driver/s3-aws/s3.go

@@ -1005,11 +1005,11 @@ ListLoop:
 // URLFor returns a URL which may be used to retrieve the content stored at the given path.
 // May return an UnsupportedMethodErr in certain StorageDriver implementations.
 func (d *driver) URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error) {
-	methodString := "GET"
+	methodString := http.MethodGet
 	method, ok := options["method"]
 	if ok {
 		methodString, ok = method.(string)
-		if !ok || (methodString != "GET" && methodString != "HEAD") {
+		if !ok || (methodString != http.MethodGet && methodString != http.MethodHead) {
 			return "", storagedriver.ErrUnsupportedMethod{}
 		}
 	}
@@ -1026,12 +1026,12 @@ func (d *driver) URLFor(ctx context.Context, path string, options map[string]int
 	var req *request.Request
 
 	switch methodString {
-	case "GET":
+	case http.MethodGet:
 		req, _ = d.S3.GetObjectRequest(&s3.GetObjectInput{
 			Bucket: aws.String(d.Bucket),
 			Key:    aws.String(d.s3Path(path)),
 		})
-	case "HEAD":
+	case http.MethodHead:
 		req, _ = d.S3.HeadObjectRequest(&s3.HeadObjectInput{
 			Bucket: aws.String(d.Bucket),
 			Key:    aws.String(d.s3Path(path)),

registry/storage/driver/swift/swift.go

@@ -608,7 +608,7 @@ func (d *driver) URLFor(ctx context.Context, path string, options map[string]int
 		return "", storagedriver.ErrUnsupportedMethod{}
 	}
 
-	methodString := "GET"
+	methodString := http.MethodGet
 	method, ok := options["method"]
 	if ok {
 		if methodString, ok = method.(string); !ok {
@@ -616,10 +616,10 @@ func (d *driver) URLFor(ctx context.Context, path string, options map[string]int
 		}
 	}
 
-	if methodString == "HEAD" {
+	if methodString == http.MethodHead {
 		// A "HEAD" request on a temporary URL is allowed if the
 		// signature was generated with "GET", "POST" or "PUT"
-		methodString = "GET"
+		methodString = http.MethodGet
 	}
 
 	supported := false

registry/storage/driver/testsuites/testsuites.go

@@ -645,7 +645,7 @@ func (suite *DriverSuite) TestURLFor(c *check.C) {
 	c.Assert(err, check.IsNil)
 	c.Assert(read, check.DeepEquals, contents)
 
-	url, err = suite.StorageDriver.URLFor(suite.ctx, filename, map[string]interface{}{"method": "HEAD"})
+	url, err = suite.StorageDriver.URLFor(suite.ctx, filename, map[string]interface{}{"method": http.MethodHead})
 	if _, ok := err.(storagedriver.ErrUnsupportedMethod); ok {
 		return
 	}