feat(fwd-proxy): Squid cache stats card — GET /forward-proxy/stats + squidclient mgr:counters

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/handlers/forwardproxy.go

@@ -4,7 +4,9 @@ import (
 	"context"
 	"errors"
 	"log/slog"
+	"os/exec"
 	"strconv"
+	"strings"
 
 	"github.com/gin-gonic/gin"
 
@@ -35,7 +37,10 @@ func (h *ForwardProxyHandler) reload(ctx context.Context, op string) {
 }
 
 func (h *ForwardProxyHandler) Register(rg *gin.RouterGroup) {
-	g := rg.Group("/forward-proxy/acls")
+	base := rg.Group("/forward-proxy")
+	base.GET("/stats", h.Stats)
+
+	g := base.Group("/acls")
 	g.GET("", h.List)
 	g.POST("", h.Create)
 	g.GET("/:id", h.Get)
@@ -135,6 +140,68 @@ func (h *ForwardProxyHandler) Delete(c *gin.Context) {
 	h.reload(c.Request.Context(), "delete")
 }
 
+// Stats liefert Squid-Cache-Statistiken via `squidclient mgr:counters`.
+// Die Ausgabe enthält HTTP-Header gefolgt von key = value Zeilen.
+func (h *ForwardProxyHandler) Stats(c *gin.Context) {
+	out, err := exec.Command("squidclient", "-h", "127.0.0.1", "-p", "3128", "mgr:counters").Output()
+	if err != nil {
+		response.OK(c, gin.H{
+			"error": "squidclient nicht verfügbar: " + err.Error(),
+		})
+		return
+	}
+	response.OK(c, gin.H{"stats": parseSquidCounters(string(out))})
+}
+
+type squidStats struct {
+	ClientRequests int64   `json:"client_requests"`
+	CacheHits      int64   `json:"cache_hits"`
+	CacheHitPct    float64 `json:"cache_hit_pct"`
+	ClientErrors   int64   `json:"client_errors"`
+	BytesIn        int64   `json:"bytes_in"`
+	BytesOut       int64   `json:"bytes_out"`
+	ServerRequests int64   `json:"server_requests"`
+	ServerErrors   int64   `json:"server_errors"`
+}
+
+func parseSquidCounters(out string) squidStats {
+	// squidclient prefixes an HTTP response header block — skip it.
+	body := out
+	if idx := strings.Index(out, "\r\n\r\n"); idx >= 0 {
+		body = out[idx+4:]
+	} else if idx := strings.Index(out, "\n\n"); idx >= 0 {
+		body = out[idx+2:]
+	}
+	s := squidStats{}
+	for _, line := range strings.Split(body, "\n") {
+		k, v, ok := strings.Cut(line, "=")
+		if !ok {
+			continue
+		}
+		n, _ := strconv.ParseInt(strings.TrimSpace(v), 10, 64)
+		switch strings.TrimSpace(k) {
+		case "client_http.requests":
+			s.ClientRequests = n
+		case "client_http.hits":
+			s.CacheHits = n
+		case "client_http.errors":
+			s.ClientErrors = n
+		case "client_http.kbytes_in":
+			s.BytesIn = n * 1024
+		case "client_http.kbytes_out":
+			s.BytesOut = n * 1024
+		case "server.all.requests":
+			s.ServerRequests = n
+		case "server.all.errors":
+			s.ServerErrors = n
+		}
+	}
+	if s.ClientRequests > 0 {
+		s.CacheHitPct = float64(s.CacheHits) / float64(s.ClientRequests) * 100
+	}
+	return s
+}
+
 // validateACL prüft Name (squid-konform), action, acl_type. Squid
 // nimmt viele Typen — wir whitelisten die, die in einem Forward-
 // Proxy-Setup üblich sind, damit Tippfehler nicht beim reload