Add request id to logs.

This change adds a GRPC interceptor that fetches the header
`Grpc-Metadata-Request-Id` and adds it to the logger. It also returns
the request id to the client in the trailer, which is helpful for
debugging.

CLI command `minder history list` was modified to show its usage, but
those changes should be reverted.

cmd/cli/app/history/history_list.go

@@ -22,9 +22,11 @@ import (
 	"strings"
 	"time"
 
+	"github.com/google/uuid"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
 	"github.com/stacklok/minder/cmd/cli/app"
@@ -116,7 +118,12 @@ func listCommand(ctx context.Context, cmd *cobra.Command, _ []string, conn *grpc
 		req.To = timestamppb.New(to)
 	}
 
-	resp, err := client.ListEvaluationHistory(ctx, req)
+	rID := uuid.New().String()
+	md := metadata.Pairs("request-id", rID)
+	ctx = metadata.NewOutgoingContext(ctx, md)
+
+	var header, trailer metadata.MD
+	resp, err := client.ListEvaluationHistory(ctx, req, grpc.Header(&header), grpc.Trailer(&trailer))
 	if err != nil {
 		return cli.MessageAndError("Error getting profile status", err)
 	}

internal/controlplane/server.go

@@ -247,6 +247,7 @@ func (s *Server) StartGRPCServer(ctx context.Context) error {
 		// TODO: this has no test coverage!
 		util.SanitizingInterceptor(),
 		logger.Interceptor(s.cfg.LoggingConfig),
+		logger.RequestIDInterceptor(),
 		TokenValidationInterceptor,
 		EntityContextProjectInterceptor,
 		ProjectAuthorizationInterceptor,

internal/logger/logging_interceptor.go

@@ -21,6 +21,7 @@ import (
 	"path"
 	"time"
 
+	"github.com/google/uuid"
 	"github.com/rs/zerolog"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/metadata"
@@ -101,3 +102,45 @@ func Interceptor(cfg config.LoggingConfig) grpc.UnaryServerInterceptor {
 		return resp, err
 	}
 }
+
+// RequestIDInterceptor traces request ids.
+//
+// It tries to use the request id from the request context, creating a
+// new one if that is missing. It also sends back in the trailer the
+// request id, ensuring that the client receives it.
+func RequestIDInterceptor() grpc.UnaryServerInterceptor {
+	return func(ctx context.Context, req interface{}, _ *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+		rID := maybeGetRequestID(ctx)
+		ctx = zerolog.Ctx(ctx).With().Str("request_id", rID).Logger().WithContext(ctx)
+
+		resp, err := handler(ctx, req)
+
+		if err := grpc.SetTrailer(ctx, metadata.Pairs("request-id", rID)); err != nil {
+			zerolog.Ctx(ctx).Trace().Err(err).Msg("unable to attach request id to trailer")
+		}
+
+		return resp, err
+	}
+}
+
+func maybeGetRequestID(ctx context.Context) string {
+	var rID string
+	if md, ok := metadata.FromIncomingContext(ctx); ok {
+		if rIDs, ok := md["request-id"]; ok {
+			if len(rIDs) != 0 {
+				rID = rIDs[0]
+			}
+		}
+	}
+
+	if rID == "" {
+		return uuid.New().String()
+	}
+
+	if _, err := uuid.Parse(rID); err != nil {
+		zerolog.Ctx(ctx).Trace().Err(err).Msg("request id is not valid uuid")
+		return uuid.New().String()
+	}
+
+	return rID
+}