add new metric to collect ban time for each jail

src/collector/f2b/socket.go

@@ -46,6 +46,11 @@ var (
 		"Total number of IPs banned by this jail (includes expired bans)",
 		[]string{"jail"}, nil,
 	)
+	metricJailBanTime = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, "config", "jail_ban_time"),
+		"How long an IP is banned for in this jail (in seconds)",
+		[]string{"jail"}, nil,
+	)
 	metricVersionInfo = prometheus.NewDesc(
 		prometheus.BuildFQName(namespace, "", "version"),
 		"Version of the exporter and fail2ban server",
@@ -98,6 +103,7 @@ func (c *Collector) collectJailMetrics(ch chan<- prometheus.Metric, s *socket.Fa
 
 	for i := range jails {
 		c.collectJailStatsMetric(ch, s, jails[i])
+		c.collectJailConfigMetrics(ch, s, jails[i])
 	}
 }
 
@@ -123,6 +129,18 @@ func (c *Collector) collectJailStatsMetric(ch chan<- prometheus.Metric, s *socke
 	)
 }
 
+func (c *Collector) collectJailConfigMetrics(ch chan<- prometheus.Metric, s *socket.Fail2BanSocket, jail string) {
+	banTime, err := s.GetJailBanTime(jail)
+	if err != nil {
+		c.socketRequestErrorCount++
+		log.Printf("failed to get ban time for jail %s: %v", jail, err)
+	} else {
+		ch <- prometheus.MustNewConstMetric(
+			metricJailBanTime, prometheus.GaugeValue, float64(banTime), jail,
+		)
+	}
+}
+
 func (c *Collector) collectVersionMetric(ch chan<- prometheus.Metric, s *socket.Fail2BanSocket) {
 	var err error
 	var fail2banVersion = ""

src/socket/fail2banSocket.go

@@ -118,6 +118,21 @@ func (s *Fail2BanSocket) GetJailStats(jail string) (JailStats, error) {
 	return stats, newBadFormatError(statusCommand, response)
 }
 
+func (s *Fail2BanSocket) GetJailBanTime(jail string) (int, error) {
+	command := fmt.Sprintf(banTimeCommandFmt, jail)
+	response, err := s.sendCommand(strings.Split(command, " "))
+	if err != nil {
+		return -1, err
+	}
+
+	if lvl1, ok := response.(*types.Tuple); ok {
+		if banTime, ok := lvl1.Get(1).(int); ok {
+			return banTime, nil
+		}
+	}
+	return -1, newBadFormatError(command, response)
+}
+
 func (s *Fail2BanSocket) GetServerVersion() (string, error) {
 	response, err := s.sendCommand([]string{versionCommand})
 	if err != nil {

src/socket/protocol.go

@@ -12,6 +12,7 @@ const (
 	pingCommand          = "ping"
 	statusCommand        = "status"
 	versionCommand       = "version"
+	banTimeCommandFmt    = "get %s bantime"
 	socketReadBufferSize = 1024
 )