Coffee journaling on ATProto (alpha)
alpha.arabica.social
coffee
feat: improved trace propagation and naming for frontend requests
authored by
Patrick Dewey
and committed by
tangled.org
4204d27e
5dd7fe2b
+32
-1
+18
-1
internal/routing/routing.go
+18
-1
internal/routing/routing.go
···
10
10
11
11
"github.com/rs/zerolog"
12
12
"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
13
+
"go.opentelemetry.io/otel/attribute"
14
+
"go.opentelemetry.io/otel/trace"
13
15
)
14
16
15
17
// Config holds the configuration needed for setting up routes
···
170
172
// 5. Apply logging middleware
171
173
handler = middleware.LoggingMiddleware(cfg.Logger)(handler)
172
174
173
-
// 6. Apply OpenTelemetry HTTP instrumentation (outermost - wraps everything)
175
+
// 6. Enrich trace spans with client page context (runs inside otelhttp span)
176
+
handler = pageContextMiddleware(handler)
177
+
178
+
// 7. Apply OpenTelemetry HTTP instrumentation (outermost - wraps everything)
174
179
handler = otelhttp.NewHandler(handler, "arabica",
175
180
otelhttp.WithFilter(func(r *http.Request) bool {
176
181
return !strings.HasPrefix(r.URL.Path, "/static/") && r.URL.Path != "/favicon.ico"
···
182
187
183
188
return handler
184
189
}
190
+
191
+
// pageContextMiddleware reads the X-Page-Context header (set by client-side JS)
192
+
// and adds it as a span attribute so traces show which page triggered the request.
193
+
func pageContextMiddleware(next http.Handler) http.Handler {
194
+
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
195
+
if page := r.Header.Get("X-Page-Context"); page != "" {
196
+
span := trace.SpanFromContext(r.Context())
197
+
span.SetAttributes(attribute.String("http.page_context", page))
198
+
}
199
+
next.ServeHTTP(w, r)
200
+
})
201
+
}
+3
internal/web/components/layout.templ
+3
internal/web/components/layout.templ
···
258
258
<script src="/static/js/data-cache.js?v=0.2.0"></script>
259
259
}
260
260
<script src="/static/js/sw-register.js?v=0.2.0"></script>
261
+
if tp := traceParentFromContext(ctx); tp != "" {
262
+
<meta name="traceparent" content={ tp }/>
263
+
}
261
264
</head>
262
265
<body
263
266
class="bg-brown-50 min-h-full flex flex-col"
+11
static/js/data-cache.js
+11
static/js/data-cache.js
···
108
108
* Fetch fresh data from the API
109
109
*/
110
110
async function fetchFreshData() {
111
+
const headers = {
112
+
"X-Page-Context": window.location.pathname,
113
+
};
114
+
115
+
// Propagate W3C traceparent from server-rendered meta tag
116
+
const tp = document.querySelector('meta[name="traceparent"]')?.content;
117
+
if (tp) {
118
+
headers["traceparent"] = tp;
119
+
}
120
+
111
121
const response = await fetch("/api/data", {
112
122
credentials: "same-origin",
123
+
headers,
113
124
});
114
125
115
126
if (!response.ok) {