From de35be477ea4931f7f3a2de1f15ecffd96c1da01 Mon Sep 17 00:00:00 2001
From: Tobias Gesellchen <tobias@gesellix.de>
Date: Sat, 21 Oct 2023 11:18:00 +0200
Subject: [PATCH] scrape

---
 couchdb-exporter.go      |  2 ++
 couchdb-exporter_test.go | 24 ++++++++++++++++--------
 lib/collector.go         | 22 ++++++++++++++++++++++
 3 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/couchdb-exporter.go b/couchdb-exporter.go
index f495d93d..7213f567 100644
--- a/couchdb-exporter.go
+++ b/couchdb-exporter.go
@@ -214,12 +214,14 @@ func main() {
 			databases = strings.Split(exporterConfig.databases, ",")
 		}
 
+		scrapeInterval, _ := time.ParseDuration("0s")
 		exporter := lib.NewExporter(
 			exporterConfig.couchdbURI,
 			lib.BasicAuth{
 				Username: exporterConfig.couchdbUsername,
 				Password: exporterConfig.couchdbPassword},
 			lib.CollectorConfig{
+				ScrapeInterval:       scrapeInterval,
 				Databases:            databases,
 				CollectViews:         exporterConfig.databaseViews,
 				CollectSchedulerJobs: exporterConfig.schedulerJobs,
diff --git a/couchdb-exporter_test.go b/couchdb-exporter_test.go
index f89e7c1d..7cf8999a 100644
--- a/couchdb-exporter_test.go
+++ b/couchdb-exporter_test.go
@@ -124,8 +124,10 @@ func performCouchdbStatsTest(t *testing.T, couchdbVersion string, expectedMetric
 	basicAuth := lib.BasicAuth{Username: "username", Password: "password"}
 	handler := http.HandlerFunc(BasicAuthHandler(basicAuth, couchdbResponse(t, couchdbVersion)))
 	server := httptest.NewServer(handler)
+	scrapeInterval, _ := time.ParseDuration("0s")
 
 	e := lib.NewExporter(server.URL, basicAuth, lib.CollectorConfig{
+		ScrapeInterval:       scrapeInterval,
 		Databases:            []string{"example", "another-example"},
 		CollectViews:         true,
 		CollectSchedulerJobs: true,
@@ -206,10 +208,12 @@ func TestCouchdbStatsV1Integration(t *testing.T) {
 		}
 	}
 
+	scrapeInterval, _ := time.ParseDuration("0s")
 	t.Run("node_up", func(t *testing.T) {
 		e := lib.NewExporter(dbUrl, basicAuth, lib.CollectorConfig{
-			Databases:    []string{},
-			CollectViews: true,
+			ScrapeInterval: scrapeInterval,
+			Databases:      []string{},
+			CollectViews:   true,
 		}, true)
 
 		ch := make(chan prometheus.Metric)
@@ -232,8 +236,9 @@ func TestCouchdbStatsV1Integration(t *testing.T) {
 
 	t.Run("_all_dbs", func(t *testing.T) {
 		e := lib.NewExporter(dbUrl, basicAuth, lib.CollectorConfig{
-			Databases:    []string{"_all_dbs"},
-			CollectViews: true,
+			ScrapeInterval: scrapeInterval,
+			Databases:      []string{"_all_dbs"},
+			CollectViews:   true,
 		}, true)
 
 		ch := make(chan prometheus.Metric)
@@ -316,10 +321,12 @@ func TestCouchdbStatsV2Integration(t *testing.T) {
 		}
 	}
 
+	scrapeInterval, _ := time.ParseDuration("0s")
 	t.Run("node_up", func(t *testing.T) {
 		e := lib.NewExporter(dbUrl, basicAuth, lib.CollectorConfig{
-			Databases:    []string{},
-			CollectViews: true,
+			ScrapeInterval: scrapeInterval,
+			Databases:      []string{},
+			CollectViews:   true,
 		}, true)
 
 		ch := make(chan prometheus.Metric)
@@ -342,8 +349,9 @@ func TestCouchdbStatsV2Integration(t *testing.T) {
 
 	t.Run("_all_dbs", func(t *testing.T) {
 		e := lib.NewExporter(dbUrl, basicAuth, lib.CollectorConfig{
-			Databases:    []string{"_all_dbs"},
-			CollectViews: true,
+			ScrapeInterval: scrapeInterval,
+			Databases:      []string{"_all_dbs"},
+			CollectViews:   true,
 		}, true)
 
 		ch := make(chan prometheus.Metric)
diff --git a/lib/collector.go b/lib/collector.go
index 2e64366d..60ad626b 100644
--- a/lib/collector.go
+++ b/lib/collector.go
@@ -2,6 +2,7 @@ package lib
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"k8s.io/klog/v2"
@@ -71,6 +72,7 @@ var (
 )
 
 type CollectorConfig struct {
+	ScrapeInterval       time.Duration
 	Databases            []string
 	ObservedDatabases    []string
 	CollectViews         bool
@@ -327,6 +329,26 @@ func (e *Exporter) collect(ch chan<- prometheus.Metric) error {
 			return err
 		}
 	}
+	return nil
+}
+
+func (e *Exporter) collect(ch chan<- prometheus.Metric) error {
+	sendStatus := func() {
+		ch <- e.up
+	}
+	defer sendStatus()
+
+	if e.collectorConfig.ScrapeInterval.Seconds() == 0 {
+		// sync
+		// old behaviour: scrape the CouchDB when the exporter is being scraped by Prometheus
+		err := e.scrape()
+		if err != nil {
+			return err
+		}
+	} else {
+		// async, continuously
+		// new behaviour: scrape the CouchDB at an interval, deliver most recent metrics when the exporter is being scraped by Prometheus
+	}
 
 	e.databasesTotal.Collect(ch)
 	e.nodeUp.Collect(ch)