TUN-8786: calculate cli flags once for the diagnostic procedure

## Summary

The flags were always being computed when their value is static.

 Closes TUN-8786

cmd/cloudflared/tunnel/cmd.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/url"
 	"os"
+	"path/filepath"
 	"runtime/trace"
 	"strings"
 	"sync"
@@ -560,15 +561,15 @@ func StartServer(
 		}
 
 		readinessServer := metrics.NewReadyServer(clientID, tracker)
+		cliFlags := nonSecretCliFlags(log, c, nonSecretFlagsList)
 		diagnosticHandler := diagnostic.NewDiagnosticHandler(
 			log,
 			0,
 			diagnostic.NewSystemCollectorImpl(buildInfo.CloudflaredVersion),
 			tunnelConfig.NamedTunnel.Credentials.TunnelID,
 			clientID,
 			tracker,
-			c,
-			nonSecretFlagsList,
+			cliFlags,
 			sources,
 		)
 		metricsConfig := metrics.Config{
@@ -1309,3 +1310,46 @@ reconnect [delay]
 		}
 	}
 }
+
+func nonSecretCliFlags(log *zerolog.Logger, cli *cli.Context, flagInclusionList []string) map[string]string {
+	flagsNames := cli.FlagNames()
+	flags := make(map[string]string, len(flagsNames))
+
+	for _, flag := range flagsNames {
+		value := cli.String(flag)
+
+		if value == "" {
+			continue
+		}
+
+		isIncluded := isFlagIncluded(flagInclusionList, flag)
+		if !isIncluded {
+			continue
+		}
+
+		switch flag {
+		case logger.LogDirectoryFlag, logger.LogFileFlag:
+			{
+				absolute, err := filepath.Abs(value)
+				if err != nil {
+					log.Error().Err(err).Msgf("could not convert %s path to absolute", flag)
+				} else {
+					flags[flag] = absolute
+				}
+			}
+		default:
+			flags[flag] = value
+		}
+	}
+	return flags
+}
+
+func isFlagIncluded(flagInclusionList []string, flag string) bool {
+	for _, include := range flagInclusionList {
+		if include == flag {
+			return true
+		}
+	}
+
+	return false
+}

diagnostic/diagnostic_utils_test.go

@@ -25,7 +25,7 @@ func helperCreateServer(t *testing.T, listeners *gracenet.Net, tunnelID uuid.UUI
 	require.NoError(t, err)
 	log := zerolog.Nop()
 	tracker := tunnelstate.NewConnTracker(&log)
-	handler := diagnostic.NewDiagnosticHandler(&log, 0, nil, tunnelID, connectorID, tracker, nil, []string{}, []string{})
+	handler := diagnostic.NewDiagnosticHandler(&log, 0, nil, tunnelID, connectorID, tracker, map[string]string{}, []string{})
 	router := http.NewServeMux()
 	router.HandleFunc("/diag/tunnel", handler.TunnelStateHandler)
 	server := &http.Server{

diagnostic/handlers.go

@@ -5,28 +5,24 @@ import (
 	"encoding/json"
 	"net/http"
 	"os"
-	"path/filepath"
 	"strconv"
 	"time"
 
 	"github.com/google/uuid"
 	"github.com/rs/zerolog"
-	"github.com/urfave/cli/v2"
 
-	"github.com/cloudflare/cloudflared/logger"
 	"github.com/cloudflare/cloudflared/tunnelstate"
 )
 
 type Handler struct {
-	log               *zerolog.Logger
-	timeout           time.Duration
-	systemCollector   SystemCollector
-	tunnelID          uuid.UUID
-	connectorID       uuid.UUID
-	tracker           *tunnelstate.ConnTracker
-	cli               *cli.Context
-	flagInclusionList []string
-	icmpSources       []string
+	log             *zerolog.Logger
+	timeout         time.Duration
+	systemCollector SystemCollector
+	tunnelID        uuid.UUID
+	connectorID     uuid.UUID
+	tracker         *tunnelstate.ConnTracker
+	cliFlags        map[string]string
+	icmpSources     []string
 }
 
 func NewDiagnosticHandler(
@@ -36,25 +32,24 @@ func NewDiagnosticHandler(
 	tunnelID uuid.UUID,
 	connectorID uuid.UUID,
 	tracker *tunnelstate.ConnTracker,
-	cli *cli.Context,
-	flagInclusionList []string,
+	cliFlags map[string]string,
 	icmpSources []string,
 ) *Handler {
 	logger := log.With().Logger()
 	if timeout == 0 {
 		timeout = defaultCollectorTimeout
 	}
 
+	cliFlags[configurationKeyUID] = strconv.Itoa(os.Getuid())
 	return &Handler{
-		log:               &logger,
-		timeout:           timeout,
-		systemCollector:   systemCollector,
-		tunnelID:          tunnelID,
-		connectorID:       connectorID,
-		tracker:           tracker,
-		cli:               cli,
-		flagInclusionList: flagInclusionList,
-		icmpSources:       icmpSources,
+		log:             &logger,
+		timeout:         timeout,
+		systemCollector: systemCollector,
+		tunnelID:        tunnelID,
+		connectorID:     connectorID,
+		tracker:         tracker,
+		cliFlags:        cliFlags,
+		icmpSources:     icmpSources,
 	}
 }
 
@@ -140,68 +135,15 @@ func (handler *Handler) ConfigurationHandler(writer http.ResponseWriter, _ *http
 		log.Info().Msg("Collection finished")
 	}()
 
-	flagsNames := handler.cli.FlagNames()
-	flags := make(map[string]string, len(flagsNames))
-
-	for _, flag := range flagsNames {
-		value := handler.cli.String(flag)
-
-		// empty values are not relevant
-		if value == "" {
-			continue
-		}
-
-		// exclude flags that are sensitive
-		isIncluded := handler.isFlagIncluded(flag)
-		if !isIncluded {
-			continue
-		}
-
-		switch flag {
-		case logger.LogDirectoryFlag:
-			fallthrough
-		case logger.LogFileFlag:
-			{
-				// the log directory may be relative to the instance thus it must be resolved
-				absolute, err := filepath.Abs(value)
-				if err != nil {
-					handler.log.Error().Err(err).Msgf("could not convert %s path to absolute", flag)
-				} else {
-					flags[flag] = absolute
-				}
-			}
-		default:
-			flags[flag] = value
-		}
-	}
-
-	// The UID is included to help the
-	// diagnostic tool to understand
-	// if this instance is managed or not.
-	flags[configurationKeyUID] = strconv.Itoa(os.Getuid())
 	encoder := json.NewEncoder(writer)
 
-	err := encoder.Encode(flags)
+	err := encoder.Encode(handler.cliFlags)
 	if err != nil {
 		handler.log.Error().Err(err).Msgf("error occurred whilst serializing response")
 		writer.WriteHeader(http.StatusInternalServerError)
 	}
 }
 
-func (handler *Handler) isFlagIncluded(flag string) bool {
-	isIncluded := false
-
-	for _, include := range handler.flagInclusionList {
-		if include == flag {
-			isIncluded = true
-
-			break
-		}
-	}
-
-	return isIncluded
-}
-
 func writeResponse(w http.ResponseWriter, bytes []byte, logger *zerolog.Logger) {
 	bytesWritten, err := w.Write(bytes)
 	if err != nil {

diagnostic/handlers_test.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
-	"flag"
 	"io"
 	"net"
 	"net/http"
@@ -15,7 +14,6 @@ import (
 	"github.com/rs/zerolog"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"github.com/urfave/cli/v2"
 
 	"github.com/cloudflare/cloudflared/connection"
 	"github.com/cloudflare/cloudflared/diagnostic"
@@ -30,21 +28,6 @@ const (
 	errorKey             = "errkey"
 )
 
-func buildCliContext(t *testing.T, flags map[string]string) *cli.Context {
-	t.Helper()
-
-	flagSet := flag.NewFlagSet("", flag.PanicOnError)
-	ctx := cli.NewContext(cli.NewApp(), flagSet, nil)
-
-	for k, v := range flags {
-		flagSet.String(k, v, "")
-		err := ctx.Set(k, v)
-		require.NoError(t, err)
-	}
-
-	return ctx
-}
-
 func newTrackerFromConns(t *testing.T, connections []tunnelstate.IndexedConnectionInfo) *tunnelstate.ConnTracker {
 	t.Helper()
 
@@ -80,7 +63,6 @@ func (*SystemCollectorMock) Collect(ctx context.Context) (*diagnostic.SystemInfo
 	si, _ := ctx.Value(systemInformationKey).(*diagnostic.SystemInformation)
 	ri, _ := ctx.Value(rawInformationKey).(string)
 	err, _ := ctx.Value(errorKey).(error)
-
 	return si, ri, err
 }
 
@@ -122,8 +104,7 @@ func TestSystemHandler(t *testing.T) {
 	for _, tCase := range tests {
 		t.Run(tCase.name, func(t *testing.T) {
 			t.Parallel()
-
-			handler := diagnostic.NewDiagnosticHandler(&log, 0, &SystemCollectorMock{}, uuid.New(), uuid.New(), nil, nil, nil, nil)
+			handler := diagnostic.NewDiagnosticHandler(&log, 0, &SystemCollectorMock{}, uuid.New(), uuid.New(), nil, map[string]string{}, nil)
 			recorder := httptest.NewRecorder()
 			ctx := setCtxValuesForSystemCollector(tCase.systemInfo, tCase.rawInfo, tCase.err)
 			request, err := http.NewRequestWithContext(ctx, http.MethodGet, "/diag/syste,", nil)
@@ -190,8 +171,7 @@ func TestTunnelStateHandler(t *testing.T) {
 				tCase.tunnelID,
 				tCase.clientID,
 				tracker,
-				nil,
-				nil,
+				map[string]string{},
 				tCase.icmpSources,
 			)
 			recorder := httptest.NewRecorder()
@@ -230,10 +210,10 @@ func TestConfigurationHandler(t *testing.T) {
 		{
 			name: "cli with flags",
 			flags: map[string]string{
-				"a": "a",
-				"b": "a",
-				"c": "a",
-				"d": "a",
+				"b":   "a",
+				"c":   "a",
+				"d":   "a",
+				"uid": "0",
 			},
 			expected: map[string]string{
 				"b":   "a",
@@ -246,11 +226,11 @@ func TestConfigurationHandler(t *testing.T) {
 
 	for _, tCase := range tests {
 		t.Run(tCase.name, func(t *testing.T) {
+			t.Parallel()
+
 			var response map[string]string
 
-			t.Parallel()
-			ctx := buildCliContext(t, tCase.flags)
-			handler := diagnostic.NewDiagnosticHandler(&log, 0, nil, uuid.New(), uuid.New(), nil, ctx, []string{"b", "c", "d"}, nil)
+			handler := diagnostic.NewDiagnosticHandler(&log, 0, nil, uuid.New(), uuid.New(), nil, tCase.flags, nil)
 			recorder := httptest.NewRecorder()
 			handler.ConfigurationHandler(recorder, nil)
 			decoder := json.NewDecoder(recorder.Body)