Allow registrar services to run in isolation (#151)

* allow separate registrars to be run in isolation using cli flag

* small cleanup so we don't have to parse unused key

Author: jmwample

cmd/registration-server/main.go

@@ -134,8 +134,11 @@ func loadConfig(configPath string) (*config, error) {
 
 func main() {
 	var configPath string
+	var apiOnly, dnsOnly bool
 
 	flag.StringVar(&configPath, "config", "", "configuration file path")
+	flag.BoolVar(&apiOnly, "api-only", false, "run only the API registrar")
+	flag.BoolVar(&dnsOnly, "dns-only", false, "run only the DNS registrar")
 	flag.Parse()
 
 	if configPath == "" {
@@ -189,22 +192,32 @@ func main() {
 		log.Fatal(err)
 	}
 
-	dnsPrivKey, err := readKey(conf.DNSPrivkeyPath)
-	if err != nil {
-		log.Fatal(err)
-	}
+	regServers := []regServer{}
+	var dnsRegServer *dnsregserver.DNSRegServer
+	var apiRegServer *apiregserver.APIRegServer
 
-	dnsRegServer, err := dnsregserver.NewDNSRegServer(conf.Domain, conf.DNSListenAddr, dnsPrivKey, processor, conf.latestClientConf.GetGeneration(), log.WithField("registrar", "DNS"), metrics)
-	if err != nil {
-		log.Fatal(err)
-	}
+	if !apiOnly {
+		dnsPrivKey, err := readKey(conf.DNSPrivkeyPath)
+		if err != nil {
+			log.Fatal(err)
+		}
 
-	apiRegServer, err := apiregserver.NewAPIRegServer(conf.APIPort, processor, conf.latestClientConf, log.WithField("registrar", "API"), logClientIP, metrics)
-	if err != nil {
-		log.Fatal(err)
+		dnsRegServer, err = dnsregserver.NewDNSRegServer(conf.Domain, conf.DNSListenAddr, dnsPrivKey, processor, conf.latestClientConf.GetGeneration(), log.WithField("registrar", "DNS"), metrics)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		regServers = append(regServers, dnsRegServer)
 	}
 
-	regServers := []regServer{dnsRegServer, apiRegServer}
+	if !dnsOnly {
+		apiRegServer, err = apiregserver.NewAPIRegServer(conf.APIPort, processor, conf.latestClientConf, log.WithField("registrar", "API"), logClientIP, metrics)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		regServers = append(regServers, apiRegServer)
+	}
 
 	signalChan := make(chan os.Signal, 1)
 
@@ -227,8 +240,13 @@ func main() {
 					if err != nil {
 						log.Errorf("failed to reload phantom subnets - aborting reload: %v", err)
 					}
-					apiRegServer.NewClientConf(conf.latestClientConf)
-					dnsRegServer.UpdateLatestCCGen(conf.latestClientConf.GetGeneration())
+					if !dnsOnly && apiRegServer != nil {
+						apiRegServer.NewClientConf(conf.latestClientConf)
+					}
+
+					if !apiOnly && dnsRegServer != nil {
+						dnsRegServer.UpdateLatestCCGen(conf.latestClientConf.GetGeneration())
+					}
 				}
 			}
 		}

pkg/dnsregserver/dnsregserver.go

@@ -3,6 +3,7 @@ package dnsregserver
 import (
 	"encoding/hex"
 	"errors"
+	"fmt"
 	"sync/atomic"
 
 	"github.com/refraction-networking/conjure/pkg/metrics"
@@ -37,7 +38,7 @@ func NewDNSRegServer(domain string, udpAddr string, privkey []byte, regprocessor
 
 	respder, err := responder.NewDnsResponder(domain, udpAddr, privkey)
 	if err != nil {
-		return nil, errors.New("failed to create DNS responder")
+		return nil, fmt.Errorf("failed to create DNS responder: %v", err)
 	}
 
 	return &DNSRegServer{