Merge branch 'feat/ping-fail2ban-server-over-socket' into 'main'

Feat/ping fail2ban server over socket

See merge request hectorjsmith/fail2ban-prometheus-exporter!23

src/cfg/cfg.go

@@ -15,6 +15,7 @@ type AppSettings struct {
 	VersionMode        bool
 	MetricsPort        int
 	Fail2BanDbPath     string
+	Fail2BanSocketPath string
 }
 
 func Parse() *AppSettings {
@@ -22,6 +23,7 @@ func Parse() *AppSettings {
 	flag.BoolVar(&appSettings.VersionMode, "version", false, "show version info and exit")
 	flag.IntVar(&appSettings.MetricsPort, "port", 9191, "port to use for the metrics server")
 	flag.StringVar(&appSettings.Fail2BanDbPath, "db", "", "path to the fail2ban sqlite database")
+	flag.StringVar(&appSettings.Fail2BanSocketPath, "socket", "", "path to the fail2ban server socket")
 
 	flag.Parse()
 	appSettings.validateFlags()
@@ -31,8 +33,8 @@ func Parse() *AppSettings {
 func (settings *AppSettings) validateFlags() {
 	var flagsValid = true
 	if !settings.VersionMode {
-		if settings.Fail2BanDbPath == "" {
-			fmt.Println("missing flag 'db'")
+		if settings.Fail2BanDbPath == "" && settings.Fail2BanSocketPath == "" {
+			fmt.Println("at least one of the following flags must be provided: 'db', 'socket'")
 			flagsValid = false
 		}
 		if settings.MetricsPort < minServerPort || settings.MetricsPort > maxServerPort {

src/exporter.go

@@ -3,15 +3,20 @@ package main
 import (
 	"fail2ban-prometheus-exporter/cfg"
 	fail2banDb "fail2ban-prometheus-exporter/db"
+	"fail2ban-prometheus-exporter/socket"
 	"fmt"
+	"log"
+	"net/http"
+
 	_ "github.com/mattn/go-sqlite3"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"log"
-	"net/http"
 )
 
-const namespace = "fail2ban"
+const (
+	namespace     = "fail2ban"
+	sockNamespace = "f2b"
+)
 
 var (
 	version = "dev"
@@ -44,29 +49,45 @@ var (
 		"Number of errors found since startup.",
 		[]string{"type"}, nil,
 	)
+	metricServerPing = prometheus.NewDesc(
+		prometheus.BuildFQName(sockNamespace, "", "up"),
+		"Check if the fail2ban server is up",
+		nil, nil,
+	)
 )
 
 type Exporter struct {
 	db           *fail2banDb.Fail2BanDB
+	socket       *socket.Fail2BanSocket
 	lastError    error
 	dbErrorCount int
 }
 
 func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
+	if e.db != nil {
 		ch <- metricUp
 		ch <- metricBadIpsPerJail
 		ch <- metricBannedIpsPerJail
 		ch <- metricEnabledJails
 		ch <- metricErrorCount
 	}
+	if e.socket != nil {
+		ch <- metricServerPing
+	}
+}
 
 func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
+	if e.db != nil {
 		e.collectBadIpsPerJailMetrics(ch)
 		e.collectBannedIpsPerJailMetrics(ch)
 		e.collectEnabledJailMetrics(ch)
 		e.collectUpMetric(ch)
 		e.collectErrorCountMetric(ch)
 	}
+	if e.socket != nil {
+		e.collectServerPingMetric(ch)
+	}
+}
 
 func (e *Exporter) collectUpMetric(ch chan<- prometheus.Metric) {
 	var upMetricValue float64 = 1
@@ -132,6 +153,17 @@ func (e *Exporter) collectEnabledJailMetrics(ch chan<- prometheus.Metric) {
 	}
 }
 
+func (e *Exporter) collectServerPingMetric(ch chan<- prometheus.Metric) {
+	pingSuccess := e.socket.Ping()
+	var pingSuccessInt float64 = 1
+	if !pingSuccess {
+		pingSuccessInt = 0
+	}
+	ch <- prometheus.MustNewConstMetric(
+		metricServerPing, prometheus.GaugeValue, pingSuccessInt,
+	)
+}
+
 func printAppVersion() {
 	fmt.Println(version)
 	fmt.Printf("    build date:  %s\r\n    commit hash: %s\r\n    built by:    %s\r\n", date, commit, builtBy)
@@ -144,8 +176,12 @@ func main() {
 	} else {
 		log.Print("starting fail2ban exporter")
 
-		exporter := &Exporter{
-			db: fail2banDb.MustConnectToDb(appSettings.Fail2BanDbPath),
+		exporter := &Exporter{}
+		if appSettings.Fail2BanDbPath != "" {
+			exporter.db = fail2banDb.MustConnectToDb(appSettings.Fail2BanDbPath)
+		}
+		if appSettings.Fail2BanSocketPath != "" {
+			exporter.socket = socket.MustConnectToSocket(appSettings.Fail2BanSocketPath)
 		}
 		prometheus.MustRegister(exporter)
 

src/go.mod

@@ -3,6 +3,8 @@ module fail2ban-prometheus-exporter
 go 1.15
 
 require (
+	github.com/kisielk/og-rek v1.1.0
 	github.com/mattn/go-sqlite3 v1.14.6
+	github.com/nlpodyssey/gopickle v0.1.0
 	github.com/prometheus/client_golang v1.9.0
 )

src/go.sum

@@ -137,6 +137,8 @@ github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7V
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
+github.com/kisielk/og-rek v1.1.0 h1:u10TvQbPtrlY/6H4+BiFsBywwSVTGFsx0YOVtpx3IbI=
+github.com/kisielk/og-rek v1.1.0/go.mod h1:6ihsOSzSAxR/65S3Bn9zNihoEqRquhDQZ2c6I2+MG3c=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.3/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=
@@ -175,6 +177,8 @@ github.com/nats-io/nats.go v1.9.1/go.mod h1:ZjDU1L/7fJ09jvUSRVBR2e7+RnLiiIQyqyzE
 github.com/nats-io/nkeys v0.1.0/go.mod h1:xpnFELMwJABBLVhffcfd1MZx6VsNRFpEugbxziKVo7w=
 github.com/nats-io/nkeys v0.1.3/go.mod h1:xpnFELMwJABBLVhffcfd1MZx6VsNRFpEugbxziKVo7w=
 github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
+github.com/nlpodyssey/gopickle v0.1.0 h1:9wjwRqXsOSYWZl4c4ko472b6RW+VB1I441ZcfFg1r5g=
+github.com/nlpodyssey/gopickle v0.1.0/go.mod h1:YIUwjJ2O7+vnBsxUN+MHAAI3N+adqEGiw+nDpwW95bY=
 github.com/oklog/oklog v0.3.2/go.mod h1:FCV+B7mhrz4o+ueLpx+KqkyXRGMWOYEvfiXtdGtbWGs=
 github.com/oklog/run v1.0.0/go.mod h1:dlhp/R75TPv97u0XWUtDeV/lRKWPKSdTuV0TZvrmrQA=
 github.com/olekukonko/tablewriter v0.0.0-20170122224234-a0225b3f23b5/go.mod h1:vsDQFd/mU46D+Z4whnwzcISnGGzXWMclvtLoiIKAKIo=

src/socket/decoder.go

@@ -0,0 +1,8 @@
+package socket
+
+// Py_builtins_str is used by the pickle decoder to parse the server response into a format Go can understand
+type Py_builtins_str struct{}
+
+func (c Py_builtins_str) Call(args ...interface{}) (interface{}, error) {
+	return args[0], nil
+}

src/socket/fail2banSocket.go

@@ -0,0 +1,42 @@
+package socket
+
+import (
+	"log"
+	"net"
+
+	"github.com/kisielk/og-rek"
+	"github.com/nlpodyssey/gopickle/types"
+)
+
+type Fail2BanSocket struct {
+	socket  net.Conn
+	encoder *ogórek.Encoder
+}
+
+func MustConnectToSocket(path string) *Fail2BanSocket {
+	c, err := net.Dial("unix", path)
+	if err != nil {
+		log.Fatalf("failed to open fail2ban socket: %v", err)
+	}
+	return &Fail2BanSocket{
+		socket:  c,
+		encoder: ogórek.NewEncoder(c),
+	}
+}
+
+func (s *Fail2BanSocket) Ping() bool {
+	response, err := s.sendCommand([]string{pingCommand, "100"})
+	if err != nil {
+		log.Printf("server ping failed: %v", err)
+		return false
+	}
+
+	if t, ok := response.(*types.Tuple); ok {
+		if (*t)[1] == "pong" {
+			return true
+		}
+		log.Printf("unexpected response data: %s", t)
+	}
+	log.Printf("unexpected response format - cannot parse: %v", response)
+	return false
+}

src/socket/protocol.go

@@ -0,0 +1,53 @@
+package socket
+
+import (
+	"bytes"
+	"fmt"
+	"github.com/nlpodyssey/gopickle/pickle"
+)
+
+const (
+	commandTerminator    = "<F2B_END_COMMAND>"
+	pingCommand          = "ping"
+	socketReadBufferSize = 10000
+)
+
+func (s *Fail2BanSocket) sendCommand(command []string) (interface{}, error) {
+	err := s.write(command)
+	if err != nil {
+		return nil, err
+	}
+	return s.read()
+}
+
+func (s *Fail2BanSocket) write(command []string) error {
+	err := s.encoder.Encode(command)
+	if err != nil {
+		return err
+	}
+	_, err = s.socket.Write([]byte(commandTerminator))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (s *Fail2BanSocket) read() (interface{}, error) {
+	buf := make([]byte, socketReadBufferSize)
+	_, err := s.socket.Read(buf)
+	if err != nil {
+		return nil, err
+	}
+
+	bufReader := bytes.NewReader(buf)
+	unpickler := pickle.NewUnpickler(bufReader)
+
+	unpickler.FindClass = func(module, name string) (interface{}, error) {
+		if module == "builtins" && name == "str" {
+			return &Py_builtins_str{}, nil
+		}
+		return nil, fmt.Errorf("class not found: " + module + " : " + name)
+	}
+
+	return unpickler.Load()
+}