feat(exporter): add prometheus exporter for cache, database & webserver stats

internal/database/database.go

@@ -2,7 +2,10 @@ package database
 
 import (
 	"errors"
+	"os"
+	"time"
 
+	"git.ar21.de/yolokube/country-geo-locations/internal/cmd"
 	"git.ar21.de/yolokube/country-geo-locations/pkg/geoloc"
 	"github.com/hashicorp/go-memdb"
 )
@@ -13,10 +16,13 @@ var (
 )
 
 type Database struct {
-	db *memdb.MemDB
+	ready bool
+
+	config *cmd.AppSettings
+	db     *memdb.MemDB
 }
 
-func NewDatabase() (*Database, error) {
+func NewDatabase(config *cmd.AppSettings) (*Database, error) {
 	database, err := memdb.NewMemDB(
 		&memdb.DBSchema{
 			Tables: map[string]*memdb.TableSchema{
@@ -38,7 +44,9 @@ func NewDatabase() (*Database, error) {
 	}
 
 	return &Database{
-		db: database,
+		ready:  false,
+		config: config,
+		db:     database,
 	}, nil
 }
 
@@ -53,9 +61,14 @@ func (d *Database) Load(ipinfos []geoloc.IPInfo) error {
 	}
 
 	txn.Commit()
+	d.ready = true
 	return nil
 }
 
+func (d *Database) IsReady() bool {
+	return d.ready
+}
+
 func (d *Database) SearchIPNet(ipnetnum uint) (*geoloc.IPInfo, error) {
 	txn := d.db.Txn(false)
 	defer txn.Abort()
@@ -87,3 +100,17 @@ func (d *Database) SearchIPNet(ipnetnum uint) (*geoloc.IPInfo, error) {
 
 	return &ipinfo, nil
 }
+
+func (d *Database) Timestamp() (time.Time, error) {
+	file, err := os.Open(d.config.DataFile)
+	if err != nil {
+		return time.Time{}, err
+	}
+
+	stats, err := file.Stat()
+	if err != nil {
+		return time.Time{}, err
+	}
+
+	return stats.ModTime(), nil
+}