interceptors: Update logging interceptor Reporter to re-extract field…

…s from context before logging (#702)

When using logging.WithFieldsFromContext, if the value being extracted
as a log field is modified after the logging interceptor initializes the
Reporter before the underlying handler is called, then the updated value
will not be reflected in the log message.

To fix this, re-extract fields from the context before logging them in
PostCall, PostMsgSend and PostMsgReceive, ensuring the updated values in
the context are logged.

Signed-off-by: Chance Zibolski <chance.zibolski@gmail.com>

interceptors/logging/interceptors.go

@@ -41,6 +41,10 @@ func (c *reporter) PostCall(err error, duration time.Duration) {
 	if err != nil {
 		fields = fields.AppendUnique(Fields{"grpc.error", fmt.Sprintf("%v", err)})
 	}
+	if c.opts.fieldsFromCtxCallMetaFn != nil {
+		// fieldsFromCtxFn dups override the existing fields.
+		fields = c.opts.fieldsFromCtxCallMetaFn(c.ctx, c.CallMeta).AppendUnique(fields)
+	}
 	c.logger.Log(c.ctx, c.opts.levelFunc(code), "finished call", fields.AppendUnique(c.opts.durationFieldFunc(duration))...)
 }
 
@@ -50,6 +54,10 @@ func (c *reporter) PostMsgSend(payload any, err error, duration time.Duration) {
 	if err != nil {
 		fields = fields.AppendUnique(Fields{"grpc.error", fmt.Sprintf("%v", err)})
 	}
+	if c.opts.fieldsFromCtxCallMetaFn != nil {
+		// fieldsFromCtxFn dups override the existing fields.
+		fields = c.opts.fieldsFromCtxCallMetaFn(c.ctx, c.CallMeta).AppendUnique(fields)
+	}
 	if !c.startCallLogged && has(c.opts.loggableEvents, StartCall) {
 		c.startCallLogged = true
 		c.logger.Log(c.ctx, logLvl, "started call", fields.AppendUnique(c.opts.durationFieldFunc(duration))...)
@@ -97,6 +105,10 @@ func (c *reporter) PostMsgReceive(payload any, err error, duration time.Duration
 	if err != nil {
 		fields = fields.AppendUnique(Fields{"grpc.error", fmt.Sprintf("%v", err)})
 	}
+	if c.opts.fieldsFromCtxCallMetaFn != nil {
+		// fieldsFromCtxFn dups override the existing fields.
+		fields = c.opts.fieldsFromCtxCallMetaFn(c.ctx, c.CallMeta).AppendUnique(fields)
+	}
 	if !c.startCallLogged && has(c.opts.loggableEvents, StartCall) {
 		c.startCallLogged = true
 		c.logger.Log(c.ctx, logLvl, "started call", fields.AppendUnique(c.opts.durationFieldFunc(duration))...)

interceptors/logging/interceptors_test.go

@@ -11,6 +11,7 @@ import (
 	"io"
 	"runtime"
 	"sort"
+	"strconv"
 	"strings"
 	"sync"
 	"testing"
@@ -172,9 +173,14 @@ type loggingClientServerSuite struct {
 	*baseLoggingSuite
 }
 
-func customFields(_ context.Context) logging.Fields {
+func customFields(ctx context.Context) logging.Fields {
+	var val string
+	n := testpb.ExtractCtxTestNumber(ctx)
+	if n != nil {
+		val = strconv.Itoa(*n)
+	}
 	// Add custom fields. The second one overrides the first one.
-	return logging.Fields{"custom-field", "foo", "custom-field", "yolo"}
+	return logging.Fields{"custom-field", "foo", "custom-field", "yolo", "custom-ctx-field", val}
 }
 
 func TestSuite(t *testing.T) {
@@ -232,13 +238,17 @@ func (s *loggingClientServerSuite) TestPing() {
 	assert.Equal(s.T(), logging.LevelDebug, serverStartCallLogLine.lvl)
 	assert.Equal(s.T(), "started call", serverStartCallLogLine.msg)
 	_ = assertStandardFields(s.T(), logging.KindServerFieldValue, serverStartCallLogLine.fields, "Ping", interceptors.Unary)
+	// This field is zero initially, but will be updated by the service, which we should see after the call is finished
+	serverStartCallLogLine.fields.AssertField(s.T(), "custom-ctx-field", "0")
 
 	serverFinishCallLogLine := lines[2]
 	assert.Equal(s.T(), logging.LevelDebug, serverFinishCallLogLine.lvl)
 	assert.Equal(s.T(), "finished call", serverFinishCallLogLine.msg)
 	serverFinishCallFields := assertStandardFields(s.T(), logging.KindServerFieldValue, serverFinishCallLogLine.fields, "Ping", interceptors.Unary)
 	serverFinishCallFields.AssertFieldNotEmpty(s.T(), "peer.address").
 		AssertField(s.T(), "custom-field", "yolo").
+		// should be updated from 0 to 42
+		AssertField(s.T(), "custom-ctx-field", "42").
 		AssertFieldNotEmpty(s.T(), "grpc.start_time").
 		AssertFieldNotEmpty(s.T(), "grpc.request.deadline").
 		AssertField(s.T(), "grpc.code", "OK").
@@ -249,6 +259,8 @@ func (s *loggingClientServerSuite) TestPing() {
 	assert.Equal(s.T(), "finished call", clientFinishCallLogLine.msg)
 	clientFinishCallFields := assertStandardFields(s.T(), logging.KindClientFieldValue, clientFinishCallLogLine.fields, "Ping", interceptors.Unary)
 	clientFinishCallFields.AssertField(s.T(), "custom-field", "yolo").
+		// should be updated from 0 to 42
+		AssertField(s.T(), "custom-ctx-field", "42").
 		AssertField(s.T(), "grpc.request.value", "something").
 		AssertFieldNotEmpty(s.T(), "grpc.start_time").
 		AssertFieldNotEmpty(s.T(), "grpc.request.deadline").
@@ -285,6 +297,8 @@ func (s *loggingClientServerSuite) TestPingList() {
 	assert.Equal(s.T(), "finished call", serverFinishCallLogLine.msg)
 	serverFinishCallFields := assertStandardFields(s.T(), logging.KindServerFieldValue, serverFinishCallLogLine.fields, "PingList", interceptors.ServerStream)
 	serverFinishCallFields.AssertField(s.T(), "custom-field", "yolo").
+		// should be updated from 0 to 42
+		AssertField(s.T(), "custom-ctx-field", "42").
 		AssertFieldNotEmpty(s.T(), "peer.address").
 		AssertFieldNotEmpty(s.T(), "grpc.start_time").
 		AssertFieldNotEmpty(s.T(), "grpc.request.deadline").
@@ -297,6 +311,8 @@ func (s *loggingClientServerSuite) TestPingList() {
 	clientFinishCallFields := assertStandardFields(s.T(), logging.KindClientFieldValue, clientFinishCallLogLine.fields, "PingList", interceptors.ServerStream)
 	clientFinishCallFields.AssertFieldNotEmpty(s.T(), "grpc.start_time").
 		AssertField(s.T(), "custom-field", "yolo").
+		// should be updated from 0 to 42
+		AssertField(s.T(), "custom-ctx-field", "42").
 		AssertFieldNotEmpty(s.T(), "grpc.request.deadline").
 		AssertField(s.T(), "grpc.code", "OK").
 		AssertFieldNotEmpty(s.T(), "grpc.time_ms").AssertNoMoreTags(s.T())
@@ -344,23 +360,27 @@ func (s *loggingClientServerSuite) TestPingError_WithCustomLevels() {
 			assert.Equal(t, "finished call", serverFinishCallLogLine.msg)
 			serverFinishCallFields := assertStandardFields(t, logging.KindServerFieldValue, serverFinishCallLogLine.fields, "PingError", interceptors.Unary)
 			serverFinishCallFields.AssertField(s.T(), "custom-field", "yolo").
+				// should be updated from 0 to 42
+				AssertField(s.T(), "custom-ctx-field", "42").
 				AssertFieldNotEmpty(t, "peer.address").
 				AssertFieldNotEmpty(t, "grpc.start_time").
 				AssertFieldNotEmpty(t, "grpc.request.deadline").
 				AssertField(t, "grpc.code", tcase.code.String()).
 				AssertField(t, "grpc.error", fmt.Sprintf("rpc error: code = %s desc = Userspace error", tcase.code.String())).
-				AssertFieldNotEmpty(t, "grpc.time_ms").AssertNoMoreTags(t)
+				AssertFieldNotEmpty(s.T(), "grpc.time_ms").AssertNoMoreTags(s.T())
 
 			clientFinishCallLogLine := lines[0]
 			assert.Equal(t, tcase.level, clientFinishCallLogLine.lvl)
 			assert.Equal(t, "finished call", clientFinishCallLogLine.msg)
 			clientFinishCallFields := assertStandardFields(t, logging.KindClientFieldValue, clientFinishCallLogLine.fields, "PingError", interceptors.Unary)
 			clientFinishCallFields.AssertField(s.T(), "custom-field", "yolo").
+				// should be updated from 0 to 42
+				AssertField(s.T(), "custom-ctx-field", "42").
 				AssertFieldNotEmpty(t, "grpc.start_time").
 				AssertFieldNotEmpty(t, "grpc.request.deadline").
 				AssertField(t, "grpc.code", tcase.code.String()).
 				AssertField(t, "grpc.error", fmt.Sprintf("rpc error: code = %s desc = Userspace error", tcase.code.String())).
-				AssertFieldNotEmpty(t, "grpc.time_ms").AssertNoMoreTags(t)
+				AssertFieldNotEmpty(s.T(), "grpc.time_ms").AssertNoMoreTags(s.T())
 		})
 	}
 }

testing/testpb/interceptor_suite.go

@@ -136,8 +136,33 @@ func (s *InterceptorTestSuite) ServerAddr() string {
 	return s.serverAddr
 }
 
+type ctxTestNumber struct{}
+
+var (
+	ctxTestNumberKey = &ctxTestNumber{}
+	zero             = 0
+)
+
+func ExtractCtxTestNumber(ctx context.Context) *int {
+	if v, ok := ctx.Value(ctxTestNumberKey).(*int); ok {
+		return v
+	}
+	return &zero
+}
+
+// UnaryServerInterceptor returns a new unary server interceptors that adds query information logging.
+func UnaryServerInterceptor() grpc.UnaryServerInterceptor {
+	return func(ctx context.Context, req any, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {
+		// newCtx := newContext(ctx, log, opts)
+		newCtx := ctx
+		resp, err := handler(newCtx, req)
+		return resp, err
+	}
+}
+
 func (s *InterceptorTestSuite) SimpleCtx() context.Context {
 	ctx, cancel := context.WithTimeout(context.TODO(), 2*time.Second)
+	ctx = context.WithValue(ctx, ctxTestNumberKey, 1)
 	s.cancels = append(s.cancels, cancel)
 	return ctx
 }

testing/testpb/pingservice.go

@@ -33,7 +33,12 @@ func (s *TestPingService) PingEmpty(_ context.Context, _ *PingEmptyRequest) (*Pi
 	return &PingEmptyResponse{}, nil
 }
 
-func (s *TestPingService) Ping(_ context.Context, ping *PingRequest) (*PingResponse, error) {
+func (s *TestPingService) Ping(ctx context.Context, ping *PingRequest) (*PingResponse, error) {
+	// Modify the ctx value to verify the logger sees the value updated from the initial value
+	n := ExtractCtxTestNumber(ctx)
+	if n != nil {
+		*n = 42
+	}
 	// Send user trailers and headers.
 	return &PingResponse{Value: ping.Value, Counter: 0}, nil
 }