Add more propagation functions (#14)

* Add more propagation functions

* Format files

* Update readme

* Readme again

* Update version

* Remove getTraceparentObject

* Remove undefined function in index.ts

* Update test equals check

* Minor test refactor

README.md

@@ -12,7 +12,7 @@ Here is an example server with log tracing enabled.
 
 ```js
 import {
-  getHttpTraceHeader,
+  getTraceparent,
   middleware,
   logger as buildLogger
 } from "@bonniernews/logger";
@@ -28,8 +28,9 @@ app.use(middleware());
 app.get("/", async (req, res) => {
   logger.info("Hello, world!");
 
-  const response = await fetch("https://some.service.bn.nr/some/endpoint", {
-    headers: { ...getHttpTraceHeader() },
+  // Propagate traceparent to other services
+  const response = await fetch("https://some.other.service.bn.nr/some/endpoint", {
+    headers: { traceparent: getTraceparent() },
   });
 
   ...
@@ -38,7 +39,8 @@ app.get("/", async (req, res) => {
 
 The `middleware` should be put as early as possible, since only logs after this middleware will get the tracing data. The middleware will lookup the active project ID from GCP. Alternatively, you can set the `GCP_PROJECT` environment variable for this purpose.
 
-Use the `getHttpTraceHeader` function to pass tracing headers to downstream services.
+Use the `getTraceparent` function to pass tracing headers to downstream services.
+Use `getTraceId` if you only want to know the current trace-id.
 
 If you want to decorate logs with custom data, use the exported `decorateLogs` function. In order to use this, the middleware needs to be installed first.
 

index.ts

@@ -1,4 +1,4 @@
-export { getHttpTraceHeader } from "./lib/http";
+export { getTraceparent, getTraceId } from "./lib/propagation";
 export { decorateLogs, logger, Logger, LoggerOptions, DestinationStream } from "./lib/logging";
 export { middleware } from "./lib/middleware";
 export { createTraceparent } from "./lib/traceparent";

lib/propagation.ts

@@ -0,0 +1,22 @@
+import { getStore } from "./middleware";
+import { getTraceFromTraceparent } from "./traceparent";
+
+/**
+ * Retrieves traceparent string from the request context store that can be used
+ * for requests to downstream services.
+ *
+ * Make sure you are using the `middleware` when using this.
+ */
+export function getTraceparent(): string | undefined {
+  return getStore()?.traceparent;
+}
+
+/**
+ * Retrieves traceId from the request context store
+ *
+ * Make sure you are using the `middleware` when using this.
+ */
+export function getTraceId(): string | undefined {
+  const { traceparent } = getStore() || {};
+  return traceparent ? getTraceFromTraceparent(traceparent)?.traceId : undefined;
+}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@bonniernews/logger",
-  "version": "0.0.7",
+  "version": "0.0.8",
   "description": "Some simple functions to use Trace Context for correlating logs",
   "type": "module",
   "main": "./dist/index.cjs",

test/unit/propagation.test.ts

@@ -0,0 +1,39 @@
+import type { RequestHandler } from "express";
+
+import { getTraceparent, getTraceId } from "../../lib/propagation";
+import { middleware as createMiddleware } from "../../lib/middleware";
+
+describe("Propagations", () => {
+  let middleware: RequestHandler;
+  const traceparent = "00-abcdef0123456789abcdef0123456789-abcdef0123456789-01";
+
+  beforeEach(() => {
+    middleware = createMiddleware();
+  });
+
+  describe("getTraceparent", () => {
+    it("should get the traceparent string from the middleware context", async () => {
+      // @ts-expect-error - We don't need the full Express Request object
+      await middleware({ header: () => traceparent }, {}, () => {
+        expect(getTraceparent()).to.equal(traceparent);
+      });
+    });
+
+    it("should return undefined if run outside the middleware context", () => {
+      expect(getTraceparent()).to.equal(undefined);
+    });
+  });
+
+  describe("getTraceId", () => {
+    it("should get the traceId from the middleware context", async () => {
+      // @ts-expect-error - We don't need the full Express Request object
+      await middleware({ header: () => traceparent }, {}, () => {
+        expect(getTraceId()).to.equal("abcdef0123456789abcdef0123456789");
+      });
+    });
+
+    it("should return undefined if run outside the middleware context", () => {
+      expect(getTraceId()).to.equal(undefined);
+    });
+  });
+});