TUN-8914: Create a flags module to group all cloudflared cli flags

## Summary

This commit refactors some of the flags of cloudflared to their own module, so that they can be used across the code without requiring to literal strings which are much more error prone.

 Closes TUN-8914

cmd/cloudflared/tunnel/subcommands.go

@@ -16,15 +16,16 @@ import (
 	"time"
 
 	"github.com/google/uuid"
-	homedir "github.com/mitchellh/go-homedir"
+	"github.com/mitchellh/go-homedir"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli/v2"
 	"github.com/urfave/cli/v2/altsrc"
 	"golang.org/x/net/idna"
-	yaml "gopkg.in/yaml.v3"
+	"gopkg.in/yaml.v3"
 
 	"github.com/cloudflare/cloudflared/cfapi"
 	"github.com/cloudflare/cloudflared/cmd/cloudflared/cliutil"
+	"github.com/cloudflare/cloudflared/cmd/cloudflared/flags"
 	"github.com/cloudflare/cloudflared/cmd/cloudflared/updater"
 	"github.com/cloudflare/cloudflared/config"
 	"github.com/cloudflare/cloudflared/connection"
@@ -48,7 +49,6 @@ const (
 	noDiagNetworkFlagName   = "no-diag-network"
 	diagContainerIDFlagName = "diag-container-id"
 	diagPodFlagName         = "diag-pod-id"
-	metricsFlagName         = "metrics"
 
 	LogFieldTunnelID = "tunnelID"
 )
@@ -60,7 +60,7 @@ var (
 		Usage:   "Include deleted tunnels in the list",
 	}
 	listNameFlag = &cli.StringFlag{
-		Name:    "name",
+		Name:    flags.Name,
 		Aliases: []string{"n"},
 		Usage:   "List tunnels with the given `NAME`",
 	}
@@ -108,7 +108,7 @@ var (
 		EnvVars: []string{"TUNNEL_LIST_INVERT_SORT"},
 	}
 	featuresFlag = altsrc.NewStringSliceFlag(&cli.StringSliceFlag{
-		Name:    "features",
+		Name:    flags.Features,
 		Aliases: []string{"F"},
 		Usage:   "Opt into various features that are still being developed or tested.",
 	})
@@ -130,14 +130,14 @@ var (
 		EnvVars: []string{"TUNNEL_TOKEN"},
 	})
 	forceDeleteFlag = &cli.BoolFlag{
-		Name:    "force",
+		Name:    flags.Force,
 		Aliases: []string{"f"},
 		Usage: "Deletes a tunnel even if tunnel is connected and it has dependencies associated to it. (eg. IP routes)." +
 			" It is not possible to delete tunnels that have connections or non-deleted dependencies, without this flag.",
 		EnvVars: []string{"TUNNEL_RUN_FORCE_OVERWRITE"},
 	}
 	selectProtocolFlag = altsrc.NewStringFlag(&cli.StringFlag{
-		Name:    "protocol",
+		Name:    flags.Protocol,
 		Value:   connection.AutoSelectFlag,
 		Aliases: []string{"p"},
 		Usage:   fmt.Sprintf("Protocol implementation to connect with Cloudflare's edge network. %s", connection.AvailableProtocolFlagMessage),
@@ -145,7 +145,7 @@ var (
 		Hidden:  true,
 	})
 	postQuantumFlag = altsrc.NewBoolFlag(&cli.BoolFlag{
-		Name:    "post-quantum",
+		Name:    flags.PostQuantum,
 		Usage:   "When given creates an experimental post-quantum secure tunnel",
 		Aliases: []string{"pq"},
 		EnvVars: []string{"TUNNEL_POST_QUANTUM"},
@@ -181,17 +181,17 @@ var (
 		EnvVars: []string{"TUNNEL_CREATE_SECRET"},
 	}
 	icmpv4SrcFlag = &cli.StringFlag{
-		Name:    "icmpv4-src",
+		Name:    flags.ICMPV4Src,
 		Usage:   "Source address to send/receive ICMPv4 messages. If not provided cloudflared will dial a local address to determine the source IP or fallback to 0.0.0.0.",
 		EnvVars: []string{"TUNNEL_ICMPV4_SRC"},
 	}
 	icmpv6SrcFlag = &cli.StringFlag{
-		Name:    "icmpv6-src",
+		Name:    flags.ICMPV6Src,
 		Usage:   "Source address and the interface name to send/receive ICMPv6 messages. If not provided cloudflared will dial a local address to determine the source IP or fallback to ::.",
 		EnvVars: []string{"TUNNEL_ICMPV6_SRC"},
 	}
 	metricsFlag = &cli.StringFlag{
-		Name:  metricsFlagName,
+		Name:  flags.Metrics,
 		Usage: "The metrics server address i.e.: 127.0.0.1:12345. If your instance is running in a Docker/Kubernetes environment you need to setup port forwarding for your application.",
 		Value: "",
 	}
@@ -231,7 +231,7 @@ var (
 		Value: false,
 	}
 	maxActiveFlowsFlag = &cli.Uint64Flag{
-		Name:    "max-active-flows",
+		Name:    flags.MaxActiveFlows,
 		Usage:   "Overrides the remote configuration for max active private network flows (TCP/UDP) that this cloudflared instance supports",
 		EnvVars: []string{"TUNNEL_MAX_ACTIVE_FLOWS"},
 	}
@@ -337,7 +337,7 @@ func listCommand(c *cli.Context) error {
 	if !c.Bool("show-deleted") {
 		filter.NoDeleted()
 	}
-	if name := c.String("name"); name != "" {
+	if name := c.String(flags.Name); name != "" {
 		filter.ByName(name)
 	}
 	if namePrefix := c.String("name-prefix"); namePrefix != "" {
@@ -467,9 +467,9 @@ func buildReadyCommand() *cli.Command {
 }
 
 func readyCommand(c *cli.Context) error {
-	metricsOpts := c.String("metrics")
-	if !c.IsSet("metrics") {
-		return fmt.Errorf("--metrics has to be provided")
+	metricsOpts := c.String(flags.Metrics)
+	if !c.IsSet(flags.Metrics) {
+		return errors.New("--metrics has to be provided")
 	}
 
 	requestURL := fmt.Sprintf("http://%s/ready", metricsOpts)
@@ -1079,7 +1079,7 @@ func diagCommand(ctx *cli.Context) error {
 	log := sctx.log
 	options := diagnostic.Options{
 		KnownAddresses: metrics.GetMetricsKnownAddresses(metrics.Runtime),
-		Address:        sctx.c.String(metricsFlagName),
+		Address:        sctx.c.String(flags.Metrics),
 		ContainerID:    sctx.c.String(diagContainerIDFlagName),
 		PodID:          sctx.c.String(diagPodFlagName),
 		Toggles: diagnostic.Toggles{