Add collector interface

Uses node_exporter style collector registration

Signed-off-by: Joe Adams <github@joeadams.io>

cmd/postgres_exporter/main.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
+	"github.com/prometheus-community/postgres_exporter/collector"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/promlog"
@@ -114,6 +115,13 @@ func main() {
 
 	prometheus.MustRegister(exporter)
 
+	pe, err := collector.NewPostgresCollector(logger, dsn)
+	if err != nil {
+		level.Error(logger).Log("msg", "Failed to create PostgresCollector", "err", err.Error())
+		os.Exit(1)
+	}
+	prometheus.MustRegister(pe)
+
 	http.Handle(*metricPath, promhttp.Handler())
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "text/html; charset=UTF-8") // nolint: errcheck

cmd/postgres_exporter/server.go

@@ -14,16 +14,13 @@
 package main
 
 import (
-	"context"
 	"database/sql"
 	"fmt"
-	"log"
 	"sync"
 	"time"
 
 	"github.com/blang/semver"
 	"github.com/go-kit/log/level"
-	"github.com/prometheus-community/postgres_exporter/collector"
 	"github.com/prometheus/client_golang/prometheus"
 )
 
@@ -131,17 +128,6 @@ func (s *Server) Scrape(ch chan<- prometheus.Metric, disableSettingsMetrics bool
 		err = fmt.Errorf("queryNamespaceMappings returned %d errors", len(errMap))
 	}
 
-	{
-		pgdb := collector.NewPGDatabaseCollector()
-		metrics, err := pgdb.Update(context.TODO(), s.db, s.String())
-		if err != nil {
-			log.Printf("Failed to scrape pg_database metrics: %s", err)
-		}
-		for _, m := range metrics {
-			ch <- m
-		}
-	}
-
 	return err
 }