TUN-4926: Implement --region configuration option

cmd/cloudflared/tunnel/cmd.go

@@ -494,6 +494,11 @@ func tunnelFlags(shouldHide bool) []cli.Flag {
 			EnvVars: []string{"TUNNEL_EDGE"},
 			Hidden:  true,
 		}),
+		altsrc.NewStringSliceFlag(&cli.StringSliceFlag{
+			Name:    "region",
+			Usage:   "Cloudflare Edge region to connect to. Omit or set to empty to connect to the global region.",
+			EnvVars: []string{"TUNNEL_REGION"},
+		}),
 		altsrc.NewStringFlag(&cli.StringFlag{
 			Name:    tlsconfig.CaCertFlag,
 			Usage:   "Certificate Authority authenticating connections with Cloudflare's edge network.",

cmd/cloudflared/tunnel/configuration.go

@@ -279,6 +279,7 @@ func prepareTunnelConfig(
 		OSArch:           buildInfo.OSArch(),
 		ClientID:         clientID,
 		EdgeAddrs:        c.StringSlice("edge"),
+		Region:           c.String("region"),
 		HAConnections:    c.Int("ha-connections"),
 		IncidentLookup:   origin.NewIncidentLookup(),
 		IsAutoupdated:    c.Bool("is-autoupdated"),