[#498] middleware: Add spans to detail the trace

Spans are added only to the following middleware:
* PolicyCheck
* Auth
* FrostfsIDValidation

This is done this way because these middleware are basic and
they interact with frostfs-storage.

Signed-off-by: Roman Loginov <r.loginov@yadro.com>

api/auth/center.go

@@ -120,7 +120,7 @@ func IsStandardContentSHA256(key string) bool {
 	return ok
 }
 
-func (c *Center) Authenticate(r *http.Request) (*middleware.Box, error) {
+func (c *Center) Authenticate(ctx context.Context, r *http.Request) (*middleware.Box, error) {
 	var (
 		err                  error
 		authHdr              *AuthHeader
@@ -152,7 +152,7 @@ func (c *Center) Authenticate(r *http.Request) (*middleware.Box, error) {
 		authHeaderField := r.Header[AuthorizationHdr]
 		if len(authHeaderField) != 1 {
 			if strings.HasPrefix(r.Header.Get(ContentTypeHdr), "multipart/form-data") {
-				return c.checkFormData(r)
+				return c.checkFormData(ctx, r)
 			}
 			return nil, fmt.Errorf("%w: %v", middleware.ErrNoAuthorizationHeader, authHeaderField)
 		}
@@ -178,7 +178,7 @@ func (c *Center) Authenticate(r *http.Request) (*middleware.Box, error) {
 		return nil, err
 	}
 
-	box, attrs, err := c.cli.GetBox(r.Context(), cnrID, authHdr.AccessKeyID)
+	box, attrs, err := c.cli.GetBox(ctx, cnrID, authHdr.AccessKeyID)
 	if err != nil {
 		return nil, fmt.Errorf("get box by access key '%s': %w", authHdr.AccessKeyID, err)
 	}
@@ -251,7 +251,7 @@ func (c Center) checkAccessKeyID(accessKeyID string) error {
 	return fmt.Errorf("%w: accesskeyID prefix isn't allowed", apierr.GetAPIError(apierr.ErrAccessDenied))
 }
 
-func (c *Center) checkFormData(r *http.Request) (*middleware.Box, error) {
+func (c *Center) checkFormData(ctx context.Context, r *http.Request) (*middleware.Box, error) {
 	if err := r.ParseMultipartForm(maxFormSizeMemory); err != nil {
 		return nil, fmt.Errorf("%w: parse multipart form with max size %d", apierr.GetAPIError(apierr.ErrInvalidArgument), maxFormSizeMemory)
 	}
@@ -283,7 +283,7 @@ func (c *Center) checkFormData(r *http.Request) (*middleware.Box, error) {
 		return nil, err
 	}
 
-	box, attrs, err := c.cli.GetBox(r.Context(), cnrID, accessKeyID)
+	box, attrs, err := c.cli.GetBox(ctx, cnrID, accessKeyID)
 	if err != nil {
 		return nil, fmt.Errorf("get box by accessKeyID '%s': %w", accessKeyID, err)
 	}

api/auth/center_test.go

@@ -385,7 +385,7 @@ func TestAuthenticate(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			creds := tokens.New(bigConfig)
 			cntr := New(creds, tc.prefixes, &centerSettingsMock{})
-			box, err := cntr.Authenticate(tc.request)
+			box, err := cntr.Authenticate(context.Background(), tc.request)
 
 			if tc.err {
 				require.Error(t, err)
@@ -563,7 +563,7 @@ func TestHTTPPostAuthenticate(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			creds := tokens.New(bigConfig)
 			cntr := New(creds, tc.prefixes, &centerSettingsMock{})
-			box, err := cntr.Authenticate(tc.request)
+			box, err := cntr.Authenticate(context.Background(), tc.request)
 
 			if tc.err {
 				require.Error(t, err)

api/auth/presign_test.go

@@ -89,7 +89,7 @@ func TestCheckSign(t *testing.T) {
 		postReg:  NewRegexpMatcher(postPolicyCredentialRegexp),
 		settings: &centerSettingsMock{},
 	}
-	box, err := c.Authenticate(req)
+	box, err := c.Authenticate(context.Background(), req)
 	require.NoError(t, err)
 	require.EqualValues(t, expBox, box.AccessBox)
 }

api/middleware/auth.go

@@ -1,6 +1,7 @@
 package middleware
 
 import (
+	"context"
 	"crypto/elliptic"
 	"errors"
 	"fmt"
@@ -8,6 +9,7 @@ import (
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/acl"
+	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
 	apierr "git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/errors"
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/creds/accessbox"
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/logs"
@@ -30,7 +32,7 @@ type (
 	Center interface {
 		// Authenticate validate and authenticate request.
 		// Must return ErrNoAuthorizationHeader if auth header is missed.
-		Authenticate(request *http.Request) (*Box, error)
+		Authenticate(ctx context.Context, request *http.Request) (*Box, error)
 	}
 
 	//nolint:revive
@@ -47,34 +49,38 @@ var ErrNoAuthorizationHeader = errors.New("no authorization header")
 func Auth(center Center, log *zap.Logger) Func {
 	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			ctx := r.Context()
-			reqInfo := GetReqInfo(ctx)
+			reqCtx := r.Context()
+			ctx, span := tracing.StartSpanFromContext(reqCtx, "middleware.Auth")
+
+			reqInfo := GetReqInfo(reqCtx)
 			reqInfo.User = "anon"
-			box, err := center.Authenticate(r)
+			box, err := center.Authenticate(ctx, r)
 			if err != nil {
 				if errors.Is(err, ErrNoAuthorizationHeader) {
-					reqLogOrDefault(ctx, log).Debug(logs.CouldntReceiveAccessBoxForGateKeyRandomKeyWillBeUsed, zap.Error(err))
+					reqLogOrDefault(reqCtx, log).Debug(logs.CouldntReceiveAccessBoxForGateKeyRandomKeyWillBeUsed, zap.Error(err))
 				} else {
-					reqLogOrDefault(ctx, log).Error(logs.FailedToPassAuthentication, zap.Error(err))
+					reqLogOrDefault(reqCtx, log).Error(logs.FailedToPassAuthentication, zap.Error(err))
 					err = apierr.TransformToS3Error(err)
 					if err.(apierr.Error).ErrCode == apierr.ErrInternalError {
 						err = apierr.GetAPIError(apierr.ErrAccessDenied)
 					}
 					if _, wrErr := WriteErrorResponse(w, GetReqInfo(r.Context()), err); wrErr != nil {
-						reqLogOrDefault(ctx, log).Error(logs.FailedToWriteResponse, zap.Error(wrErr))
+						reqLogOrDefault(reqCtx, log).Error(logs.FailedToWriteResponse, zap.Error(wrErr))
 					}
+					span.End()
 					return
 				}
 			} else {
-				ctx = SetBox(ctx, box)
+				reqCtx = SetBox(reqCtx, box)
 
 				if box.AccessBox.Gate.BearerToken != nil {
 					reqInfo.User = bearer.ResolveIssuer(*box.AccessBox.Gate.BearerToken).String()
 				}
-				reqLogOrDefault(ctx, log).Debug(logs.SuccessfulAuth, zap.String("accessKeyID", box.AuthHeaders.AccessKeyID))
+				reqLogOrDefault(reqCtx, log).Debug(logs.SuccessfulAuth, zap.String("accessKeyID", box.AuthHeaders.AccessKeyID))
 			}
 
-			h.ServeHTTP(w, r.WithContext(ctx))
+			span.End()
+			h.ServeHTTP(w, r.WithContext(reqCtx))
 		})
 	}
 }
@@ -86,22 +92,26 @@ type FrostFSIDValidator interface {
 func FrostfsIDValidation(frostfsID FrostFSIDValidator, log *zap.Logger) Func {
 	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			ctx := r.Context()
+			ctx, span := tracing.StartSpanFromContext(r.Context(), "middleware.FrostfsIDValidation")
+
 			bd, err := GetBoxData(ctx)
 			if err != nil || bd.Gate.BearerToken == nil {
 				reqLogOrDefault(ctx, log).Debug(logs.AnonRequestSkipFrostfsIDValidation)
+				span.End()
 				h.ServeHTTP(w, r)
 				return
 			}
 
 			if err = validateBearerToken(frostfsID, bd.Gate.BearerToken); err != nil {
 				reqLogOrDefault(ctx, log).Error(logs.FrostfsIDValidationFailed, zap.Error(err))
-				if _, wrErr := WriteErrorResponse(w, GetReqInfo(r.Context()), err); wrErr != nil {
+				if _, wrErr := WriteErrorResponse(w, GetReqInfo(ctx), err); wrErr != nil {
 					reqLogOrDefault(ctx, log).Error(logs.FailedToWriteResponse, zap.Error(wrErr))
 				}
+				span.End()
 				return
 			}
 
+			span.End()
 			h.ServeHTTP(w, r)
 		})
 	}

api/middleware/policy.go

@@ -10,6 +10,7 @@ import (
 	"net/url"
 	"strings"
 
+	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/data"
 	apierr "git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/errors"
 	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/logs"
@@ -85,23 +86,26 @@ type PolicyConfig struct {
 func PolicyCheck(cfg PolicyConfig) Func {
 	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			ctx := r.Context()
-			if err := policyCheck(r, cfg); err != nil {
+			ctx, span := tracing.StartSpanFromContext(r.Context(), "middleware.PolicyCheck")
+
+			if err := policyCheck(ctx, r, cfg); err != nil {
 				reqLogOrDefault(ctx, cfg.Log).Error(logs.PolicyValidationFailed, zap.Error(err))
 				err = apierr.TransformToS3Error(err)
 				if _, wrErr := WriteErrorResponse(w, GetReqInfo(ctx), err); wrErr != nil {
 					reqLogOrDefault(ctx, cfg.Log).Error(logs.FailedToWriteResponse, zap.Error(wrErr))
 				}
+				span.End()
 				return
 			}
 
+			span.End()
 			h.ServeHTTP(w, r)
 		})
 	}
 }
 
-func policyCheck(r *http.Request, cfg PolicyConfig) error {
-	reqInfo := GetReqInfo(r.Context())
+func policyCheck(ctx context.Context, r *http.Request, cfg PolicyConfig) error {
+	reqInfo := GetReqInfo(ctx)
 
 	req, userKey, userGroups, err := getPolicyRequest(r, cfg, reqInfo.RequestType, reqInfo.BucketName, reqInfo.ObjectName)
 	if err != nil {
@@ -110,7 +114,7 @@ func policyCheck(r *http.Request, cfg PolicyConfig) error {
 
 	var bktInfo *data.BucketInfo
 	if reqInfo.RequestType != noneType && !strings.HasSuffix(req.Operation(), CreateBucketOperation) {
-		bktInfo, err = cfg.BucketResolver(r.Context(), reqInfo.BucketName)
+		bktInfo, err = cfg.BucketResolver(ctx, reqInfo.BucketName)
 		if err != nil {
 			return err
 		}

api/router_mock_test.go

@@ -45,7 +45,7 @@ type centerMock struct {
 	key          *keys.PrivateKey
 }
 
-func (c *centerMock) Authenticate(*http.Request) (*middleware.Box, error) {
+func (c *centerMock) Authenticate(context.Context, *http.Request) (*middleware.Box, error) {
 	if c.noAuthHeader {
 		return nil, middleware.ErrNoAuthorizationHeader
 	}