From 9de0efa42fabad0655b2d232b490e8f426f3bab2 Mon Sep 17 00:00:00 2001
From: Freerk-Ole Zakfeld <fzakfeld@scaleuptech.com>
Date: Wed, 14 May 2025 20:28:02 +0200
Subject: [PATCH] Add NEUTRON_ROUTER_EXTERNAL_NETWORK_ID Filter

Signed-off-by: Freerk-Ole Zakfeld <fzakfeld@scaleuptech.com>
---
 README.md                 |  4 ++++
 exporters/neutron.go      | 14 ++++++++------
 exporters/neutron_test.go |  4 ++--
 main.go                   |  6 +++++-
 4 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index cf64687..0e3f0e9 100644
--- a/README.md
+++ b/README.md
@@ -52,4 +52,8 @@ DESIGNATE_ENABLED=true
 MANILA_ENABLED=false
 NEUTRON_ENABLED=true
 OCTAVIA_ENABLED=true
+
+# Routers returned by the Neutron Exporter are filtered by a specific external network ID.
+# This is designed to only count the usage of routers which are connected to an external network.
+NEUTRON_ROUTER_EXTERNAL_NETWORK_ID=5d8722dd-186c-4e32-a170-b216a04688dc
 ```
diff --git a/exporters/neutron.go b/exporters/neutron.go
index e344b5d..b8f8306 100644
--- a/exporters/neutron.go
+++ b/exporters/neutron.go
@@ -8,14 +8,16 @@ import (
 )
 
 type NeutronUsageExporter struct {
-	db          *sql.DB
-	floatingIPs *prometheus.Desc
-	routers     *prometheus.Desc
+	db                *sql.DB
+	externalNetworkId string
+	floatingIPs       *prometheus.Desc
+	routers           *prometheus.Desc
 }
 
-func NewNeutronUsageExporter(db *sql.DB) (*NeutronUsageExporter, error) {
+func NewNeutronUsageExporter(db *sql.DB, externalNetworkId string) (*NeutronUsageExporter, error) {
 	return &NeutronUsageExporter{
-		db: db,
+		db:                db,
+		externalNetworkId: externalNetworkId,
 		floatingIPs: prometheus.NewDesc(
 			"openstack_project_floating_ips",
 			"Total number of floating IPs per OpenStack project",
@@ -63,7 +65,7 @@ func (e *NeutronUsageExporter) collectMetrics(ch chan<- prometheus.Metric) {
 	}
 
 	routerCounts := make(map[string]float64)
-	rows, err = e.db.Query("SELECT project_id, COUNT(id) AS total_routers FROM routers GROUP BY project_id")
+	rows, err = e.db.Query("SELECT r.project_id, COUNT(r.id) AS total_routers FROM routers r INNER JOIN ports p ON r.gw_port_id = p.id WHERE p.network_id = ? GROUP BY r.project_id", e.externalNetworkId)
 	if err != nil {
 		log.Println("Error querying router counts:", err)
 		return
diff --git a/exporters/neutron_test.go b/exporters/neutron_test.go
index f8a3145..6a51368 100644
--- a/exporters/neutron_test.go
+++ b/exporters/neutron_test.go
@@ -23,9 +23,9 @@ func TestNeutronUsageExporter(t *testing.T) {
 	routerRows := sqlmock.NewRows([]string{"project_id", "total_routers"}).
 		AddRow("c352b0ed-30ca-4634-9c2d-1947efc29096", 1).
 		AddRow("6ee08ba2-2ca1-4c91-b139-4bf0dbaa4096", 2)
-	mock.ExpectQuery("SELECT project_id, COUNT\\(id\\) AS total_routers FROM routers GROUP BY project_id").WillReturnRows(routerRows)
+	mock.ExpectQuery("SELECT r.project_id, COUNT\\(r.id\\) AS total_routers FROM routers r").WithArgs("5d8722dd-186c-4e32-a170-b216a04688dc").WillReturnRows(routerRows)
 
-	exporter, err := NewNeutronUsageExporter(db)
+	exporter, err := NewNeutronUsageExporter(db, "5d8722dd-186c-4e32-a170-b216a04688dc")
 	if err != nil {
 		t.Fatalf("Failed to create NeutronUsageExporter: %v", err)
 	}
diff --git a/main.go b/main.go
index e834263..e3ad72f 100644
--- a/main.go
+++ b/main.go
@@ -69,7 +69,11 @@ func main() {
 			}
 			exporter, err = exporters.NewNovaTraitUsageExporter(db, trait)
 		case "neutron":
-			exporter, err = exporters.NewNeutronUsageExporter(db)
+			externalNetworkId, exists := os.LookupEnv("NEUTRON_ROUTER_EXTERNAL_NETWORK_ID")
+			if !exists {
+				log.Fatalf("NEUTRON_ROUTER_EXTERNAL_NETWORK_ID not set")
+			}
+			exporter, err = exporters.NewNeutronUsageExporter(db, externalNetworkId)
 		case "designate":
 			exporter, err = exporters.NewDesignateUsageExporter(db)
 		case "octavia":