From 8a9d19498477e67bd0a52c9542e02c31a9b42bfe Mon Sep 17 00:00:00 2001
From: Simon Rieger <simon@rieger.app>
Date: Thu, 17 Jul 2025 03:15:14 +0200
Subject: [PATCH] add logging

---
 main.go | 117 +++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 70 insertions(+), 47 deletions(-)

diff --git a/main.go b/main.go
index c7b3d4d..5359e0c 100644
--- a/main.go
+++ b/main.go
@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"regexp"
 	"strings"
+	"sync"
 
 	"github.com/docker/docker/api/types/image"
 	"github.com/docker/docker/client"
@@ -16,7 +17,7 @@ import (
 	"github.com/regclient/regclient/types/ref"
 )
 
-// Hilfsfunktion: registrykompatibles Format aus repo:tag erzeugen
+// Hilfsfunktion: registry/repo:tag für regclient
 func toRegistryImage(imageTag string) (string, error) {
 	r := regexp.MustCompile(`^(?:(?P<registry>[^/]+)/)?(?P<repo>[^:]+)(?::(?P<tag>.+))?$`)
 	match := r.FindStringSubmatch(imageTag)
@@ -35,7 +36,7 @@ func toRegistryImage(imageTag string) (string, error) {
 	return fmt.Sprintf("%s/%s:%s", registry, repo, tag), nil
 }
 
-// Extrahiert nur den sha256:... Digest
+// Extrahiere nur den sha256:digest
 func extractDigest(s string) string {
 	for _, part := range strings.Split(s, "@") {
 		if strings.HasPrefix(part, "sha256:") {
@@ -45,31 +46,30 @@ func extractDigest(s string) string {
 	return s
 }
 
-// Prometheus Collector-Struktur
-type dockerImageUpdateCollector struct {
-	desc *prometheus.Desc
+type imageUpdateCollector struct {
+	metric *prometheus.Desc
 }
 
-func newDockerImageUpdateCollector() prometheus.Collector {
-	return &dockerImageUpdateCollector{
-		desc: prometheus.NewDesc(
+func newImageUpdateCollector() *imageUpdateCollector {
+	return &imageUpdateCollector{
+		metric: prometheus.NewDesc(
 			"docker_image_update_available",
-			"Whether a new image digest is available for this local image tag (1=update, 0=current)",
-			[]string{"image"},
+			"Ob Update für das lokale Docker-Image für das Tag im Registry verfügbar ist (1=Update, 0=aktuell)",
+			[]string{"image", "tag"},
 			nil,
 		),
 	}
 }
 
-func (c *dockerImageUpdateCollector) Describe(ch chan<- *prometheus.Desc) {
-	ch <- c.desc
+func (c *imageUpdateCollector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- c.metric
 }
 
-func (c *dockerImageUpdateCollector) Collect(ch chan<- prometheus.Metric) {
+func (c *imageUpdateCollector) Collect(ch chan<- prometheus.Metric) {
 	ctx := context.Background()
 	cli, err := client.NewClientWithOpts(client.FromEnv)
 	if err != nil {
-		log.Println("Docker-Client-Fehler:", err)
+		log.Printf("Fehler bei Docker-Client: %v", err)
 		return
 	}
 	defer cli.Close()
@@ -77,48 +77,71 @@ func (c *dockerImageUpdateCollector) Collect(ch chan<- prometheus.Metric) {
 
 	images, err := cli.ImageList(ctx, image.ListOptions{All: true})
 	if err != nil {
-		log.Println("Docker-ImageList-Fehler:", err)
+		log.Printf("Fehler bei ImageList: %v", err)
 		return
 	}
 
+	var wg sync.WaitGroup
 	for _, img := range images {
 		for _, tag := range img.RepoTags {
-			imageRef, err := toRegistryImage(tag)
-			if err != nil {
-				continue
-			}
-			var localDigest string
-			if len(img.RepoDigests) > 0 {
-				localDigest = extractDigest(img.RepoDigests[0])
-			} else {
-				localDigest = img.ID
-			}
-			refObj, err := ref.New(imageRef)
-			if err != nil {
-				continue
-			}
-			desc, err := rc.ManifestHead(ctx, refObj)
-			if err != nil {
-				continue
-			}
-			remoteDigest := desc.GetDigest().String()
-			var value float64 = 0
-			if localDigest != remoteDigest {
-				value = 1
-			}
-			ch <- prometheus.MustNewConstMetric(
-				c.desc,
-				prometheus.GaugeValue,
-				value,
-				tag,
-			)
+			wg.Add(1)
+			go func(tag string, img image.Summary) {
+				defer wg.Done()
+				imageRef, err := toRegistryImage(tag)
+				if err != nil {
+					log.Printf("ImageRef-Fehler bei %s: %v", tag, err)
+					return
+				}
+
+				// Lokalen Digest holen
+				var localDigest string
+				if len(img.RepoDigests) > 0 {
+					localDigest = extractDigest(img.RepoDigests[0])
+				} else {
+					localDigest = img.ID
+				}
+
+				// Remote Digest holen
+				refObj, err := ref.New(imageRef)
+				if err != nil {
+					log.Printf("ImageRef (regclient) ungültig (%s): %v", tag, err)
+					return
+				}
+				desc, err := rc.ManifestHead(ctx, refObj)
+				if err != nil {
+					log.Printf("Remote-Manifest nicht gefunden (%s): %v", tag, err)
+					return
+				}
+				remoteDigest := desc.GetDigest().String()
+
+				// Logging
+				fmt.Printf("Image: %s\n  Local Digest:  %s\n  Remote Digest: %s\n", tag, localDigest, remoteDigest)
+				var update float64 = 0
+				if localDigest != remoteDigest {
+					fmt.Println("  -> Update verfügbar!")
+					update = 1
+				} else {
+					fmt.Println("  -> Kein Update verfügbar.")
+				}
+
+				labelImg, labelTag := tag, "latest"
+				if cp := strings.Split(tag, ":"); len(cp) == 2 {
+					labelImg, labelTag = cp[0], cp[1]
+				}
+				ch <- prometheus.MustNewConstMetric(
+					c.metric, prometheus.GaugeValue,
+					update, labelImg, labelTag,
+				)
+			}(tag, img)
 		}
 	}
+	wg.Wait()
 }
 
 func main() {
-	prometheus.MustRegister(newDockerImageUpdateCollector())
+	log.Println("Starte Docker-Image-Update Prometheus Exporter (Port 9788)...")
+	exporter := newImageUpdateCollector()
+	prometheus.MustRegister(exporter)
 	http.Handle("/metrics", promhttp.Handler())
-	log.Println("Prometheus Exporter läuft auf :9888/metrics")
-	log.Fatal(http.ListenAndServe(":9888", nil))
+	log.Fatal(http.ListenAndServe(":9788", nil))
 }