feat(config): autoreload on config changes

cmd/gobgpd/main.go

@@ -28,6 +28,7 @@ import (
 	"os/signal"
 	"runtime"
 	"syscall"
+	"time"
 
 	"github.com/coreos/go-systemd/v22/daemon"
 	grpc_prometheus "github.com/grpc-ecosystem/go-grpc-prometheus"
@@ -36,6 +37,7 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/sirupsen/logrus"
+	"golang.org/x/time/rate"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 
@@ -52,26 +54,27 @@ func main() {
 	signal.Notify(sigCh, syscall.SIGTERM, syscall.SIGINT)
 
 	var opts struct {
-		ConfigFile      string `short:"f" long:"config-file" description:"specifying a config file"`
-		ConfigType      string `short:"t" long:"config-type" description:"specifying config type (toml, yaml, json)" default:"toml"`
-		LogLevel        string `short:"l" long:"log-level" description:"specifying log level"`
-		LogPlain        bool   `short:"p" long:"log-plain" description:"use plain format for logging (json by default)"`
-		UseSyslog       string `short:"s" long:"syslog" description:"use syslogd"`
-		Facility        string `long:"syslog-facility" description:"specify syslog facility"`
-		DisableStdlog   bool   `long:"disable-stdlog" description:"disable standard logging"`
-		CPUs            int    `long:"cpus" description:"specify the number of CPUs to be used"`
-		GrpcHosts       string `long:"api-hosts" description:"specify the hosts that gobgpd listens on" default:":50051"`
-		GracefulRestart bool   `short:"r" long:"graceful-restart" description:"flag restart-state in graceful-restart capability"`
-		Dry             bool   `short:"d" long:"dry-run" description:"check configuration"`
-		PProfHost       string `long:"pprof-host" description:"specify the host that gobgpd listens on for pprof and metrics" default:"localhost:6060"`
-		PProfDisable    bool   `long:"pprof-disable" description:"disable pprof profiling"`
-		MetricsPath     string `long:"metrics-path" description:"specify path for prometheus metrics, empty value disables them" default:"/metrics"`
-		UseSdNotify     bool   `long:"sdnotify" description:"use sd_notify protocol"`
-		TLS             bool   `long:"tls" description:"enable TLS authentication for gRPC API"`
-		TLSCertFile     string `long:"tls-cert-file" description:"The TLS cert file"`
-		TLSKeyFile      string `long:"tls-key-file" description:"The TLS key file"`
-		TLSClientCAFile string `long:"tls-client-ca-file" description:"Optional TLS client CA file to authenticate clients against"`
-		Version         bool   `long:"version" description:"show version number"`
+		ConfigFile       string `short:"f" long:"config-file" description:"specifying a config file"`
+		ConfigType       string `short:"t" long:"config-type" description:"specifying config type (toml, yaml, json)" default:"toml"`
+		ConfigAutoReload bool   `short:"a" long:"config-auto-reload" description:"activate config auto reload on changes"`
+		LogLevel         string `short:"l" long:"log-level" description:"specifying log level"`
+		LogPlain         bool   `short:"p" long:"log-plain" description:"use plain format for logging (json by default)"`
+		UseSyslog        string `short:"s" long:"syslog" description:"use syslogd"`
+		Facility         string `long:"syslog-facility" description:"specify syslog facility"`
+		DisableStdlog    bool   `long:"disable-stdlog" description:"disable standard logging"`
+		CPUs             int    `long:"cpus" description:"specify the number of CPUs to be used"`
+		GrpcHosts        string `long:"api-hosts" description:"specify the hosts that gobgpd listens on" default:":50051"`
+		GracefulRestart  bool   `short:"r" long:"graceful-restart" description:"flag restart-state in graceful-restart capability"`
+		Dry              bool   `short:"d" long:"dry-run" description:"check configuration"`
+		PProfHost        string `long:"pprof-host" description:"specify the host that gobgpd listens on for pprof and metrics" default:"localhost:6060"`
+		PProfDisable     bool   `long:"pprof-disable" description:"disable pprof profiling"`
+		MetricsPath      string `long:"metrics-path" description:"specify path for prometheus metrics, empty value disables them" default:"/metrics"`
+		UseSdNotify      bool   `long:"sdnotify" description:"use sd_notify protocol"`
+		TLS              bool   `long:"tls" description:"enable TLS authentication for gRPC API"`
+		TLSCertFile      string `long:"tls-cert-file" description:"The TLS cert file"`
+		TLSKeyFile       string `long:"tls-key-file" description:"The TLS key file"`
+		TLSClientCAFile  string `long:"tls-client-ca-file" description:"Optional TLS client CA file to authenticate clients against"`
+		Version          bool   `long:"version" description:"show version number"`
 	}
 	_, err := flags.Parse(&opts)
 	if err != nil {
@@ -235,6 +238,26 @@ func main() {
 		}).Fatalf("Failed to apply initial configuration %s", opts.ConfigFile)
 	}
 
+	if opts.ConfigAutoReload {
+		logger.WithFields(logrus.Fields{
+			"Topic": "Config",
+		}).Info("Watching for config changes to trigger auto-reload")
+
+		// Writing to the config may trigger many events in quick successions
+		// To prevent abusive reloads, we ignore any event in a 100ms window
+		rateLimiter := rate.Sometimes{Interval: 100 * time.Millisecond}
+
+		config.WatchConfigFile(opts.ConfigFile, opts.ConfigType, func() {
+			rateLimiter.Do(func() {
+				logger.WithFields(logrus.Fields{
+					"Topic": "Config",
+				}).Info("Config changes detected, reloading configuration")
+
+				sigCh <- syscall.SIGHUP
+			})
+		})
+	}
+
 	for sig := range sigCh {
 		if sig != syscall.SIGHUP {
 			stopServer(bgpServer, opts.UseSdNotify)

docs/sources/getting-started.md

@@ -44,7 +44,7 @@ $ sudo -E gobgpd -f gobgpd.conf
 If you use a configuration format other than `toml`, you must specify the format
 by `-t` option.
 
-equivalent yaml configuration.
+Equivalent yaml configuration.
 
 ```yaml
 global:
@@ -66,6 +66,9 @@ $ sudo -E gobgpd -t yaml -f gobgpd.yml
 {"level":"info","msg":"Peer 10.0.255.2 is added","time":"2015-04-06T20:32:28+09:00"}
 ```
 
+Sending the `SIGHUP` signal to `gobgpd` triggers a configuration reload.
+The `-a` option enables the auto reloading of the configuration whenever a change is detected.
+
 Let's show the information of all the peers.
 
 ```bash

go.mod

@@ -5,6 +5,7 @@ require (
 	github.com/coreos/go-systemd/v22 v22.5.0
 	github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13
 	github.com/eapache/channels v1.1.0
+	github.com/fsnotify/fsnotify v1.6.0
 	github.com/go-test/deep v1.1.0
 	github.com/google/go-cmp v0.5.9
 	github.com/google/uuid v1.3.0
@@ -20,6 +21,7 @@ require (
 	github.com/vishvananda/netlink v1.2.1-beta.2
 	golang.org/x/sys v0.6.0
 	golang.org/x/text v0.8.0
+	golang.org/x/time v0.3.0
 	google.golang.org/grpc v1.53.0
 	google.golang.org/protobuf v1.30.0
 )
@@ -29,7 +31,6 @@ require (
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/eapache/queue v1.1.0 // indirect
-	github.com/fsnotify/fsnotify v1.6.0 // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect

go.sum

@@ -466,6 +466,10 @@ golang.org/x/text v0.8.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
+golang.org/x/time v0.1.0 h1:xYY+Bajn2a7VBmTM5GikTmnK8ZuX8YgnQCqZpbBNtmA=
+golang.org/x/time v0.1.0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
+golang.org/x/time v0.3.0 h1:rg5rLMjNzMS1RkNLzCG38eapWhnYLFYXDXj2gOlr8j4=
+golang.org/x/time v0.3.0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=

internal/pkg/config/serve.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"github.com/fsnotify/fsnotify"
 	"github.com/spf13/viper"
 
 	"github.com/osrg/gobgp/v3/pkg/log"
@@ -42,6 +43,18 @@ func ReadConfigfile(path, format string) (*BgpConfigSet, error) {
 	return config, nil
 }
 
+func WatchConfigFile(path, format string, callBack func()) {
+	v := viper.New()
+	v.SetConfigFile(path)
+	v.SetConfigType(format)
+
+	v.OnConfigChange(func(e fsnotify.Event) {
+		callBack()
+	})
+
+	v.WatchConfig()
+}
+
 func ConfigSetToRoutingPolicy(c *BgpConfigSet) *RoutingPolicy {
 	return &RoutingPolicy{
 		DefinedSets:       c.DefinedSets,

pkg/config/config.go

@@ -20,6 +20,12 @@ func ReadConfigFile(configFile, configType string) (*config.BgpConfigSet, error)
 	return config.ReadConfigfile(configFile, configType)
 }
 
+// WatchConfigFile calls the callback function anytime an update to the
+// config file is detected.
+func WatchConfigFile(configFile, configType string, callBack func()) {
+	config.WatchConfigFile(configFile, configType, callBack)
+}
+
 func marshalRouteTargets(l []string) ([]*apb.Any, error) {
 	rtList := make([]*apb.Any, 0, len(l))
 	for _, rtString := range l {