From 22312a1b72e1f4ac33bd71bd4754c366ad399fda Mon Sep 17 00:00:00 2001
From: Seongmin Lee <git@boltless.me>
Date: Mon, 11 May 2026 20:34:18 +0900
Subject: [PATCH] knotmirror: add more metrics

Signed-off-by: Seongmin Lee <git@boltless.me>
---
 knotmirror/xrpc/git_get_tree.go       |  1 +
 knotmirror/xrpc/git_list_languages.go |  1 +
 knotmirror/xrpc/metrics.go            | 19 ++++++++++++++
 knotmirror/xrpc/xrpc.go               | 38 +++++++++++++++++++++++++++
 4 files changed, 59 insertions(+)
 create mode 100644 knotmirror/xrpc/metrics.go

diff --git a/knotmirror/xrpc/git_get_tree.go b/knotmirror/xrpc/git_get_tree.go
index 51f8c3c8..ada01e41 100644
--- a/knotmirror/xrpc/git_get_tree.go
+++ b/knotmirror/xrpc/git_get_tree.go
@@ -23,6 +23,7 @@ func (x *Xrpc) GetTree(w http.ResponseWriter, r *http.Request) {
 		path      = r.URL.Query().Get("path") // path can be empty (defaults to root)
 	)
 	l := x.logger.With("method", "git.getTree", "repo", repoQuery, "ref", ref)
+	l.Debug("call")
 
 	repo, err := syntax.ParseATURI(repoQuery)
 	if err != nil || repo.RecordKey() == "" {
diff --git a/knotmirror/xrpc/git_list_languages.go b/knotmirror/xrpc/git_list_languages.go
index 7507a218..b0c3573a 100644
--- a/knotmirror/xrpc/git_list_languages.go
+++ b/knotmirror/xrpc/git_list_languages.go
@@ -19,6 +19,7 @@ func (x *Xrpc) ListLanguages(w http.ResponseWriter, r *http.Request) {
 		ref       = r.URL.Query().Get("ref")
 	)
 	l := x.logger.With("method", "git.listLanguages", "repo", repoQuery, "ref", ref)
+	l.Debug("call")
 
 	repo, err := syntax.ParseATURI(repoQuery)
 	if err != nil || repo.RecordKey() == "" {
diff --git a/knotmirror/xrpc/metrics.go b/knotmirror/xrpc/metrics.go
new file mode 100644
index 00000000..e09c44cc
--- /dev/null
+++ b/knotmirror/xrpc/metrics.go
@@ -0,0 +1,19 @@
+package xrpc
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	xrpcRequestsTotal = promauto.NewCounterVec(prometheus.CounterOpts{
+		Name: "knotmirror_xrpc_requests_total",
+		Help: "Total number of xrpc requests handled, labeled by method (NSID), repo at-uri, and HTTP status",
+	}, []string{"method", "repo", "status"})
+
+	xrpcRequestDuration = promauto.NewHistogramVec(prometheus.HistogramOpts{
+		Name:    "knotmirror_xrpc_request_duration_seconds",
+		Help:    "Duration of xrpc requests, labeled by method (NSID) and repo at-uri",
+		Buckets: prometheus.ExponentialBuckets(0.001, 2, 16),
+	}, []string{"method", "repo"})
+)
diff --git a/knotmirror/xrpc/xrpc.go b/knotmirror/xrpc/xrpc.go
index 37827abf..1734353f 100644
--- a/knotmirror/xrpc/xrpc.go
+++ b/knotmirror/xrpc/xrpc.go
@@ -6,10 +6,13 @@ import (
 	"errors"
 	"log/slog"
 	"net/http"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/bluesky-social/indigo/atproto/atclient"
 	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
 	"tangled.org/core/api/tangled"
 	"tangled.org/core/idresolver"
 	"tangled.org/core/knotmirror/config"
@@ -42,6 +45,8 @@ func New(logger *slog.Logger, cfg *config.Config, db *sql.DB, resolver *idresolv
 func (x *Xrpc) Router() http.Handler {
 	r := chi.NewRouter()
 
+	r.Use(x.metrics)
+
 	r.Get("/"+tangled.GitTempGetArchiveNSID, x.GetArchive)
 	r.Get("/"+tangled.GitTempGetBlobNSID, x.GetBlob)
 	r.Get("/"+tangled.GitTempGetBranchNSID, x.GetBranch)
@@ -61,6 +66,39 @@ func (x *Xrpc) Router() http.Handler {
 	return r
 }
 
+func (x *Xrpc) metrics(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		method := strings.TrimPrefix(r.URL.Path, "/xrpc/")
+		repo := r.URL.Query().Get("repo")
+		ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+		start := time.Now()
+
+		next.ServeHTTP(ww, r)
+
+		duration := time.Since(start)
+		status := ww.Status()
+		if status == 0 {
+			status = http.StatusOK
+		}
+
+		xrpcRequestsTotal.WithLabelValues(method, repo, strconv.Itoa(status)).Inc()
+		xrpcRequestDuration.WithLabelValues(method, repo).Observe(duration.Seconds())
+
+		attrs := []any{
+			"method", method,
+			"status", status,
+			"duration_ms", duration.Milliseconds(),
+		}
+		for k, v := range r.URL.Query() {
+			if len(v) == 1 {
+				attrs = append(attrs, k, v[0])
+			} else {
+				attrs = append(attrs, k, v)
+			}
+		}
+	})
+}
+
 func writeJson(w http.ResponseWriter, status int, response any) error {
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(status)
-- 
2.51.2