Skip to content

fix: Add http path prefix as metrics labels #111

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
nssherpa merged 1 commit into from
Feb 12, 2026
Merged

fix: Add http path prefix as metrics labels #111

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
20 changes: 19 additions & 1 deletion cmd/cachewd/main.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ import (
"github.com/alecthomas/kong"
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"

"github.com/block/cachew/internal/cache"
"github.com/block/cachew/internal/config"
Expand Down Expand Up @@ -156,10 +157,27 @@ func newMux(ctx context.Context, cr *cache.Registry, sr *strategy.Registry, prov
return mux, nil
}

// extractPathPrefix extracts the strategy name, path prefix from a request path.
// Examples: /git/... -> "git", /gomod/... -> "gomod", /api/v1/... -> "api".
func extractPathPrefix(path string) string {
if path == "" || path == "/" {
return ""
}
trimmed := strings.TrimPrefix(path, "/")
prefix, _, _ := strings.Cut(trimmed, "/")
return prefix
}

func newServer(ctx context.Context, mux *http.ServeMux, bind string, metricsConfig metrics.Config) *http.Server {
logger := logging.FromContext(ctx)
var handler http.Handler = mux

var handler http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
labeler, _ := otelhttp.LabelerFromContext(r.Context())
labeler.Add(attribute.String("cachew.http.path.prefix", extractPathPrefix(r.URL.Path)))
mux.ServeHTTP(w, r)
})

// Add standard otelhttp middleware
handler = otelhttp.NewMiddleware(metricsConfig.ServiceName,
otelhttp.WithMeterProvider(otel.GetMeterProvider()),
otelhttp.WithTracerProvider(otel.GetTracerProvider()),
Expand Down