From 756ebfa0f3d42b0966af3e45ce325f8ac73dd2e7 Mon Sep 17 00:00:00 2001
From: Julien Pinsonneau <jpinsonn@redhat.com>
Date: Thu, 22 Feb 2024 10:14:18 +0100
Subject: [PATCH] add 'different' filter to prom metrics

---
 pkg/api/api.go                            |  1 +
 pkg/api/encode_prom.go                    | 11 +++---
 pkg/pipeline/encode/encode_prom_metric.go | 42 +++++++++++++++--------
 3 files changed, 34 insertions(+), 20 deletions(-)

diff --git a/pkg/api/api.go b/pkg/api/api.go
index 0bbc0d725..2ff4fbe93 100644
--- a/pkg/api/api.go
+++ b/pkg/api/api.go
@@ -51,6 +51,7 @@ const (
 	AddKubernetesInfraRuleType   = "add_kubernetes_infra"
 	ReinterpretDirectionRuleType = "reinterpret_direction"
 	PromFilterExact              = "exact"
+	PromFilterDifferent          = "different"
 	PromFilterPresence           = "presence"
 	PromFilterAbsence            = "absence"
 	PromFilterRegex              = "regex"
diff --git a/pkg/api/encode_prom.go b/pkg/api/encode_prom.go
index 07213d613..98faff43c 100644
--- a/pkg/api/encode_prom.go
+++ b/pkg/api/encode_prom.go
@@ -70,14 +70,15 @@ type MetricsItems []MetricsItem
 type MetricsFilter struct {
 	Key   string `yaml:"key" json:"key" doc:"the key to match and filter by"`
 	Value string `yaml:"value" json:"value" doc:"the value to match and filter by"`
-	Type  string `yaml:"type" json:"type" enum:"MetricEncodeFilterTypeEnum" doc:"the type of filter match: exact (default), presence, absence or regex"`
+	Type  string `yaml:"type" json:"type" enum:"MetricEncodeFilterTypeEnum" doc:"the type of filter match: exact (default), different, presence, absence or regex"`
 }
 
 type MetricEncodeFilterTypeEnum struct {
-	Exact    string `yaml:"exact" json:"exact" doc:"match exactly the provided fitler value"`
-	Presence string `yaml:"presence" json:"presence" doc:"filter key must be present (filter value is ignored)"`
-	Absence  string `yaml:"absence" json:"absence" doc:"filter key must be absent (filter value is ignored)"`
-	Regex    string `yaml:"regex" json:"regex" doc:"match filter value as a regular expression"`
+	Exact     string `yaml:"exact" json:"exact" doc:"match exactly the provided fitler value"`
+	Different string `yaml:"different" json:"different" doc:"not match the provided fitler value"`
+	Presence  string `yaml:"presence" json:"presence" doc:"filter key must be present (filter value is ignored)"`
+	Absence   string `yaml:"absence" json:"absence" doc:"filter key must be absent (filter value is ignored)"`
+	Regex     string `yaml:"regex" json:"regex" doc:"match filter value as a regular expression"`
 }
 
 func MetricEncodeFilterTypeName(t string) string {
diff --git a/pkg/pipeline/encode/encode_prom_metric.go b/pkg/pipeline/encode/encode_prom_metric.go
index 15fe7854e..38586f81e 100644
--- a/pkg/pipeline/encode/encode_prom_metric.go
+++ b/pkg/pipeline/encode/encode_prom_metric.go
@@ -15,30 +15,29 @@ type MetricInfo struct {
 	FilterPredicates []Predicate
 }
 
-func Presence(filter api.MetricsFilter) Predicate {
+func presence(filter api.MetricsFilter) Predicate {
 	return func(flow config.GenericMap) bool {
 		_, found := flow[filter.Key]
 		return found
 	}
 }
 
-func Absence(filter api.MetricsFilter) Predicate {
+func absence(filter api.MetricsFilter) Predicate {
 	return func(flow config.GenericMap) bool {
 		_, found := flow[filter.Key]
 		return !found
 	}
 }
 
-func Exact(filter api.MetricsFilter) Predicate {
+func exact(filter api.MetricsFilter) Predicate {
 	return func(flow config.GenericMap) bool {
-		if val, found := flow[filter.Key]; found {
-			sVal, ok := val.(string)
-			if !ok {
-				sVal = fmt.Sprint(val)
-			}
-			return sVal == filter.Value
-		}
-		return false
+		return matchExactly(flow, filter)
+	}
+}
+
+func different(filter api.MetricsFilter) Predicate {
+	return func(flow config.GenericMap) bool {
+		return !matchExactly(flow, filter)
 	}
 }
 
@@ -59,16 +58,18 @@ func regex(filter api.MetricsFilter) Predicate {
 func filterToPredicate(filter api.MetricsFilter) Predicate {
 	switch filter.Type {
 	case api.PromFilterExact:
-		return Exact(filter)
+		return exact(filter)
+	case api.PromFilterDifferent:
+		return different(filter)
 	case api.PromFilterPresence:
-		return Presence(filter)
+		return presence(filter)
 	case api.PromFilterAbsence:
-		return Absence(filter)
+		return absence(filter)
 	case api.PromFilterRegex:
 		return regex(filter)
 	}
 	// Default = Exact
-	return Exact(filter)
+	return exact(filter)
 }
 
 func CreateMetricInfo(def api.MetricsItem) *MetricInfo {
@@ -80,3 +81,14 @@ func CreateMetricInfo(def api.MetricsItem) *MetricInfo {
 	}
 	return &mi
 }
+
+func matchExactly(flow config.GenericMap, filter api.MetricsFilter) bool {
+	if val, found := flow[filter.Key]; found {
+		sVal, ok := val.(string)
+		if !ok {
+			sVal = fmt.Sprint(val)
+		}
+		return sVal == filter.Value
+	}
+	return false
+}