contrib/go-chi/chi: add appsec monitoring (DataDog#1130)

contrib/go-chi/chi.v4/appsec.go

@@ -0,0 +1,32 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016 Datadog, Inc.
+
+package chi
+
+import (
+	"net/http"
+
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/appsec/dyngo/instrumentation/httpsec"
+
+	"github.com/go-chi/chi/v4"
+)
+
+func withAppsec(next http.Handler, r *http.Request, span tracer.Span) http.Handler {
+	rctx := chi.RouteContext(r.Context())
+	if rctx == nil {
+		return httpsec.WrapHandler(next, span, nil)
+	}
+	var pathParams map[string]string
+	keys := rctx.URLParams.Keys
+	values := rctx.URLParams.Values
+	if len(keys) > 0 && len(keys) == len(values) {
+		pathParams = make(map[string]string, len(keys))
+		for i, key := range keys {
+			pathParams[key] = values[i]
+		}
+	}
+	return httpsec.WrapHandler(next, span, pathParams)
+}

contrib/go-chi/chi.v4/chi.go

@@ -0,0 +1,89 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016 Datadog, Inc.
+
+// Package chi provides tracing functions for tracing the go-chi/chi/v4 package (https://github.com/go-chi/chi).
+package chi // import "gopkg.in/DataDog/dd-trace-go.v1/contrib/go-chi/chi.v4"
+
+import (
+	"fmt"
+	"math"
+	"net/http"
+	"strconv"
+
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/appsec"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/log"
+
+	"github.com/go-chi/chi/v4"
+	"github.com/go-chi/chi/v4/middleware"
+)
+
+// Middleware returns middleware that will trace incoming requests.
+func Middleware(opts ...Option) func(next http.Handler) http.Handler {
+	cfg := new(config)
+	defaults(cfg)
+	for _, fn := range opts {
+		fn(cfg)
+	}
+	log.Debug("contrib/go-chi/chi.v4: Configuring Middleware: %#v", cfg)
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if cfg.ignoreRequest(r) {
+				next.ServeHTTP(w, r)
+				return
+			}
+			opts := []ddtrace.StartSpanOption{
+				tracer.SpanType(ext.SpanTypeWeb),
+				tracer.ServiceName(cfg.serviceName),
+				tracer.Tag(ext.HTTPMethod, r.Method),
+				tracer.Tag(ext.HTTPURL, r.URL.Path),
+				tracer.Measured(),
+			}
+			if !math.IsNaN(cfg.analyticsRate) {
+				opts = append(opts, tracer.Tag(ext.EventSampleRate, cfg.analyticsRate))
+			}
+			if spanctx, err := tracer.Extract(tracer.HTTPHeadersCarrier(r.Header)); err == nil {
+				opts = append(opts, tracer.ChildOf(spanctx))
+			}
+			opts = append(opts, cfg.spanOpts...)
+			span, ctx := tracer.StartSpanFromContext(r.Context(), "http.request", opts...)
+			defer span.Finish()
+
+			if appsec.Enabled() {
+				next = withAppsec(next, r, span)
+				// Note that the following response writer passed to the handler
+				// implements the `interface { Status() int }` expected by httpsec.
+			}
+
+			ww := middleware.NewWrapResponseWriter(w, r.ProtoMajor)
+
+			// pass the span through the request context and serve the request to the next middleware
+			next.ServeHTTP(ww, r.WithContext(ctx))
+
+			// set the resource name as we get it only once the handler is executed
+			resourceName := chi.RouteContext(r.Context()).RoutePattern()
+			if resourceName == "" {
+				resourceName = "unknown"
+			}
+			resourceName = r.Method + " " + resourceName
+			span.SetTag(ext.ResourceName, resourceName)
+
+			// set the status code
+			status := ww.Status()
+			// 0 status means one has not yet been sent in which case net/http library will write StatusOK
+			if ww.Status() == 0 {
+				status = http.StatusOK
+			}
+			span.SetTag(ext.HTTPCode, strconv.Itoa(status))
+
+			if cfg.isStatusError(status) {
+				// mark 5xx server error
+				span.SetTag(ext.Error, fmt.Errorf("%d: %s", status, http.StatusText(status)))
+			}
+		})
+	}
+}