feat(node): Add docs for async context apis

src/platforms/node/common/configuration/async-context.mdx

@@ -0,0 +1,40 @@
+---
+title: Async Context
+sidebar_order: 80
+description: "Learn more about how to isolate Sentry scope and breadcrumbs across requests."
+---
+
+You can use the `runWithAsyncContext` method to isolate Sentry scope and breadcrumbs to a single request if you are using SDK v7.48.0 or higher. This is useful if you are finding that breadcrumbs and scope are leaking across requests.
+
+```js
+const Sentry = require("@sentry/node");
+
+function requestHandlerMiddleware(req, res, next) {
+  // Any breadcrumbs or tags added will be isolated to the request
+  return Sentry.runWithAsyncContext(
+    () => {
+      return next(req, res);
+    },
+    { emitters: [req, res] }
+  );
+}
+```
+
+Under the hood, the SDK uses Node's [AsyncLocalStorage API](https://nodejs.org/api/async_context.html#class-asynclocalstorage) to perform the isolation.
+
+On lower SDK versions you'll have to use [domains](https://nodejs.org/api/domain.html) to isolate Sentry scope and breadcrumbs to a single request.
+
+```js
+const domain = require("domain");
+
+function myRequestHandler(req, res, next) {
+  const localDomain = domain.create();
+
+  localDomain.add(req);
+  localDomain.add(res);
+
+  return localDomain.bind(() => {
+    return next(req, res);
+  })();
+}
+```

src/platforms/node/guides/express/index.mdx

@@ -167,7 +167,7 @@ Sentry.init({
   tracesSampleRate: 1.0,
 });
 
-// RequestHandler creates a separate execution context using domains, so that every
+// RequestHandler creates a separate execution context, so that every
 // transaction/span/breadcrumb is attached to its own Hub instance
 app.use(Sentry.Handlers.requestHandler());
 // TracingHandler creates a trace for every incoming request

src/platforms/node/guides/express/performance/index.mdx

@@ -35,7 +35,7 @@ Sentry.init({
   tracesSampleRate: 1.0,
 });
 
-// RequestHandler creates a separate execution context using domains, so that every
+// RequestHandler creates a separate execution context, so that every
 // transaction/span/breadcrumb is attached to its own Hub instance
 app.use(Sentry.Handlers.requestHandler());
 // TracingHandler creates a trace for every incoming request
@@ -132,6 +132,7 @@ app.get("/success", function successHandler(req, res) {
 ## Connecting Services
 
 If you are also using Performance Monitoring for [JavaScript](/platforms/javascript/performance/), depending on where your request originates, you can connect traces:
+
 1. For requests that start in your backend, by [adding a meta tag](/platforms/javascript/performance/connect-services/#pageload) in your HTML template that contains tracing information.
 2. For requests that start in JavaScript, by the SDK [setting a header](/platforms/javascript/performance/connect-services/#navigation-and-other-xhr-requests) on requests to your backend.
 

src/platforms/node/guides/express/performance/instrumentation/automatic-instrumentation.mdx

@@ -37,7 +37,7 @@ Sentry.init({
   tracesSampleRate: 1.0,
 });
 
-// RequestHandler creates a separate execution context using domains, so that every
+// RequestHandler creates a separate execution context, so that every
 // transaction/span/breadcrumb is attached to its own Hub instance
 app.use(Sentry.Handlers.requestHandler());
 // TracingHandler creates a trace for every incoming request

src/platforms/node/guides/koa/index.mdx

@@ -49,7 +49,6 @@ const Sentry = require("@sentry/node");
 const { stripUrlQueryAndFragment } = require("@sentry/utils");
 const Koa = require("koa");
 const app = new Koa();
-const domain = require("domain");
 
 Sentry.init({
   dsn: "___PUBLIC_DSN___",
@@ -64,30 +63,25 @@ Sentry.init({
   ],
 });
 
-// not mandatory, but adding domains does help a lot with breadcrumbs
 const requestHandler = (ctx, next) => {
   return new Promise((resolve, reject) => {
-    const local = domain.create();
-    local.add(ctx);
-    local.on("error", err => {
-      ctx.status = err.status || 500;
-      ctx.body = err.message;
-      ctx.app.emit("error", err, ctx);
-      reject(err);
-    });
-    local.run(async () => {
-      Sentry.getCurrentHub().configureScope(scope =>
-        scope.addEventProcessor(event =>
-          Sentry.addRequestDataToEvent(event, ctx.request, {
-            include: {
-              user: false,
-            },
-          });
+    Sentry.runWithAsyncContext(
+      async hub => {
+        hub.configureScope(scope =>
+          scope.addEventProcessor(event =>
+            Sentry.addRequestDataToEvent(event, ctx.request, {
+              include: {
+                user: false,
+              },
+            })
+          )
         );
-      );
-      await next();
-      resolve();
-    });
+
+        await next();
+        resolve();
+      },
+      { emitters: [ctx] }
+    );
   });
 };
 
@@ -99,7 +93,9 @@ const tracingMiddleWare = async (ctx, next) => {
   // connect to trace of upstream app
   let traceparentData;
   if (ctx.request.get("sentry-trace")) {
-    traceparentData = Sentry.extractTraceparentData(ctx.request.get("sentry-trace"));
+    traceparentData = Sentry.extractTraceparentData(
+      ctx.request.get("sentry-trace")
+    );
   }
 
   const transaction = Sentry.startTransaction({
@@ -136,7 +132,7 @@ app.use(tracingMiddleWare);
 
 // usual error handler
 app.on("error", (err, ctx) => {
-  Sentry.withScope((scope) => {
+  Sentry.withScope(scope => {
     scope.addEventProcessor(event => {
       return Sentry.addRequestDataToEvent(event, ctx.request);
     });

src/platforms/node/guides/serverless-cloud/index.mdx

@@ -142,7 +142,7 @@ Sentry.init({
   // tracesSampleRate: parseFloat(params.SENTRY_TRACES_SAMPLE_RATE),
 });
 
-// RequestHandler creates a separate execution context using domains, so that every
+// RequestHandler creates a separate execution context, so that every
 // transaction/span/breadcrumb is attached to its own Hub instance
 api.use(Sentry.Handlers.requestHandler());
 // TracingHandler creates a trace for every incoming request

src/wizard/node/express.md

@@ -44,7 +44,7 @@ Sentry.init({
   tracesSampleRate: 1.0,
 });
 
-// RequestHandler creates a separate execution context using domains, so that every
+// RequestHandler creates a separate execution context, so that every
 // transaction/span/breadcrumb is attached to its own Hub instance
 app.use(Sentry.Handlers.requestHandler());
 // TracingHandler creates a trace for every incoming request

src/wizard/node/serverlesscloud.md

@@ -43,7 +43,7 @@ Sentry.init({
   // tracesSampleRate: parseFloat(params.SENTRY_TRACES_SAMPLE_RATE),
 });
 
-// RequestHandler creates a separate execution context using domains, so that every
+// RequestHandler creates a separate execution context, so that every
 // transaction/span/breadcrumb is attached to its own Hub instance
 api.use(Sentry.Handlers.requestHandler());
 // TracingHandler creates a trace for every incoming request