fix Panic for prometheus metrics when CustomFields are set

config.go

@@ -28,7 +28,7 @@ func getConfig() *types.Configuration {
 	version := kingpin.Flag("version", "falcosidekick version").Short('v').Bool()
 	kingpin.Parse()
 
-	if *version != false {
+	if *version {
 		v := GetVersionInfo()
 		fmt.Println(v.String())
 		os.Exit(0)
@@ -334,7 +334,7 @@ func getConfig() *types.Configuration {
 		}
 	}
 
-	v.GetStringMapString("customfields")
+	v.GetStringMapString("Customfields")
 	v.GetStringMapString("Webhook.CustomHeaders")
 	v.GetStringMapString("CloudEvents.Extensions")
 	if err := v.Unmarshal(c); err != nil {
@@ -352,8 +352,8 @@ func getConfig() *types.Configuration {
 	}
 
 	if value, present := os.LookupEnv("WEBHOOK_CUSTOMHEADERS"); present {
-		customfields := strings.Split(value, ",")
-		for _, label := range customfields {
+		customheaders := strings.Split(value, ",")
+		for _, label := range customheaders {
 			tagkeys := strings.Split(label, ":")
 			if len(tagkeys) == 2 {
 				c.Webhook.CustomHeaders[tagkeys[0]] = tagkeys[1]
@@ -362,8 +362,8 @@ func getConfig() *types.Configuration {
 	}
 
 	if value, present := os.LookupEnv("CLOUDEVENTS_EXTENSIONS"); present {
-		customfields := strings.Split(value, ",")
-		for _, label := range customfields {
+		extensions := strings.Split(value, ",")
+		for _, label := range extensions {
 			tagkeys := strings.Split(label, ":")
 			if len(tagkeys) == 2 {
 				c.CloudEvents.Extensions[tagkeys[0]] = tagkeys[1]
@@ -384,7 +384,7 @@ func getConfig() *types.Configuration {
 	}
 
 	if c.Prometheus.ExtraLabels != "" {
-		c.Prometheus.ExtraLabelsList = strings.Split(strings.ReplaceAll(c.Loki.ExtraLabels, " ", ""), ",")
+		c.Prometheus.ExtraLabelsList = strings.Split(strings.ReplaceAll(c.Prometheus.ExtraLabels, " ", ""), ",")
 	}
 
 	c.Slack.MinimumPriority = checkPriority(c.Slack.MinimumPriority)

config_example.yaml

@@ -83,7 +83,7 @@ loki:
   # checkcert: true # check if ssl certificate of the output is valid (default: true)
   # tenant: "" # Add the tenant header if needed. Tenant header is enabled only if not empty
   # endpoint: "/api/prom/push" # The endpoint URL path, default is "/api/prom/push" more info : https://grafana.com/docs/loki/latest/api/#post-apiprompush
-  # extralabels: "" # comma separated list of fields to use as labels additionnally to rule, source, priority, tags and custom_fields
+  # extralabels: "" # comma separated list of fields to use as labels additionally to rule, source, priority, tags and custom_fields
 
 nats:
   # hostport: "" # nats://{domain or ip}:{port}, if not empty, NATS output is enabled
@@ -135,7 +135,7 @@ smtp:
   # minimumpriority: "" # minimum priority of event for using this output, order is emergency|alert|critical|error|warning|notice|informational|debug or "" (default)
 
 prometheus:
-  # extralabels: "" # comma separated list of fields to use as labels additionnally to rule, source, priority, tags and custom_fields
+  # extralabels: "" # comma separated list of fields to use as labels additionally to rule, source, priority, tags and custom_fields
 
 statsd:
   forwarder: "" # The address for the StatsD forwarder, in the form "host:port", if not empty StatsD is enabled

handlers.go

@@ -111,7 +111,22 @@ func newFalcoPayload(payload io.Reader) (types.FalcoPayload, error) {
 	stats.Falco.Add(strings.ToLower(falcopayload.Priority.String()), 1)
 	promLabels := map[string]string{"rule": falcopayload.Rule, "priority": falcopayload.Priority.String(), "k8s_ns_name": kn, "k8s_pod_name": kp}
 	for key, value := range config.Customfields {
-		promLabels[key] = value
+		if regPromLabels.MatchString(key) {
+			promLabels[key] = value
+		}
+	}
+	for _, i := range config.Prometheus.ExtraLabelsList {
+		promLabels[strings.ReplaceAll(i, ".", "_")] = ""
+		for key, value := range falcopayload.OutputFields {
+			if key == i && regPromLabels.MatchString(strings.ReplaceAll(key, ".", "_")) {
+				switch v := value.(type) {
+				case string:
+					promLabels[strings.ReplaceAll(key, ".", "_")] = v
+				default:
+					continue
+				}
+			}
+		}
 	}
 	promStats.Falco.With(promLabels).Inc()
 
@@ -279,8 +294,7 @@ func forwardEvent(falcopayload types.FalcoPayload) {
 	if config.Fission.Function != "" && (falcopayload.Priority >= types.Priority(config.Fission.MinimumPriority) || falcopayload.Rule == testRule) {
 		go fissionClient.FissionCall(falcopayload)
 	}
-	if config.PolicyReport.Enabled == true {
-
+	if config.PolicyReport.Enabled {
 		go policyReportClient.UpdateOrCreatePolicyReport(falcopayload)
 	}
 

main.go

@@ -5,6 +5,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"regexp"
 	"strings"
 
 	"github.com/DataDog/datadog-go/statsd"
@@ -58,6 +59,8 @@ var (
 	config                        *types.Configuration
 	stats                         *types.Statistics
 	promStats                     *types.PromStatistics
+
+	regPromLabels *regexp.Regexp
 )
 
 func init() {
@@ -68,6 +71,9 @@ func init() {
 	if testing {
 		return
 	}
+
+	regPromLabels, _ = regexp.Compile("^[a-zA-Z_:][a-zA-Z0-9_:]*$")
+
 	config = getConfig()
 	stats = getInitStats()
 	promStats = getInitPromStats(config)
@@ -434,7 +440,7 @@ func init() {
 			outputs.EnabledOutputs = append(outputs.EnabledOutputs, "WebUI")
 		}
 	}
-	if config.PolicyReport.Enabled == true {
+	if config.PolicyReport.Enabled {
 		var err error
 		policyReportClient, err = outputs.NewPolicyReportClient(config, stats, promStats, statsdClient, dogstatsdClient)
 		if err != nil {

outputs/loki.go

@@ -33,8 +33,15 @@ func newLokiPayload(falcopayload types.FalcoPayload, config *types.Configuration
 	for i, j := range falcopayload.OutputFields {
 		switch v := j.(type) {
 		case string:
-			if contains(config.Loki.ExtraLabelsList, i) {
-				s += strings.ReplaceAll(strings.ReplaceAll(strings.ReplaceAll(i, ".", ""), "]", ""), "[", "") + "=\"" + strings.ReplaceAll(v, "\"", "") + "\","
+			for k := range config.Customfields {
+				if i == k {
+					s += strings.ReplaceAll(strings.ReplaceAll(strings.ReplaceAll(i, ".", ""), "]", ""), "[", "") + "=\"" + strings.ReplaceAll(v, "\"", "") + "\","
+				}
+			}
+			for _, k := range config.Loki.ExtraLabelsList {
+				if i == k {
+					s += strings.ReplaceAll(strings.ReplaceAll(strings.ReplaceAll(i, ".", ""), "]", ""), "[", "") + "=\"" + strings.ReplaceAll(v, "\"", "") + "\","
+				}
 			}
 		default:
 			continue
@@ -47,9 +54,9 @@ func newLokiPayload(falcopayload types.FalcoPayload, config *types.Configuration
 
 	s += "rule=\"" + falcopayload.Rule + "\","
 	s += "source=\"" + falcopayload.Source + "\","
-	s += "priority=\"" + falcopayload.Priority.String() + "\","
+	s += "priority=\"" + falcopayload.Priority.String() + "\""
 
-	ls.Labels = "{" + s[:len(s)-1] + "}"
+	ls.Labels = "{" + s + "}"
 
 	return lokiPayload{Streams: []lokiStream{ls}}
 }

outputs/utils.go

@@ -15,12 +15,3 @@ func getSortedStringKeys(m map[string]interface{}) []string {
 	sort.Strings(keys)
 	return keys
 }
-
-func contains(slice []string, str string) bool {
-	for _, i := range slice {
-		if i == str {
-			return true
-		}
-	}
-	return false
-}

stats_prometheus.go

@@ -3,6 +3,7 @@ package main
 import (
 	"log"
 	"regexp"
+	"strings"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
@@ -38,22 +39,26 @@ func getOutputNewCounterVec() *prometheus.CounterVec {
 }
 
 func getFalcoNewCounterVec(config *types.Configuration) *prometheus.CounterVec {
+	regPromLabels, _ := regexp.Compile("^[a-zA-Z_:][a-zA-Z0-9_:]*$")
 	labelnames := []string{
 		"rule",
 		"priority",
 		"k8s_ns_name",
 		"k8s_pod_name",
 	}
-	labelnames = append(labelnames, config.Prometheus.ExtraLabelsList...)
-	for key := range config.Customfields {
-		matched, err := regexp.MatchString("^[a-zA-Z_:][a-zA-Z0-9_:]*$", key)
-		if err != nil {
-			log.Printf("Error matching prometheus label from custom fields. Err: %s", err)
+	for i := range config.Customfields {
+		if !regPromLabels.MatchString(i) {
+			log.Printf("[ERROR] : Custom field '%v' is not a valid prometheus label", i)
 			continue
 		}
-		if matched {
-			labelnames = append(labelnames, key)
+		labelnames = append(labelnames, i)
+	}
+	for _, i := range config.Prometheus.ExtraLabelsList {
+		if !regPromLabels.MatchString(strings.ReplaceAll(i, ".", "_")) {
+			log.Printf("[ERROR] : Extra field '%v' is not a valid prometheus label", i)
+			continue
 		}
+		labelnames = append(labelnames, strings.ReplaceAll(i, ".", "_"))
 	}
 	return promauto.NewCounterVec(
 		prometheus.CounterOpts{