feat: accept both w3c and honeycomb propagation headers by default (#514

) * attempt to parse incoming header as w3c (even if no hook specified) if w3c header found - unless honeycomb header also found, then default to that. Co-authored-by: Robb Kidd <robbkidd@honeycomb.io>
honeycombio · Dec 20, 2021 · 07a2eac · 07a2eac
1 parent 8d1d590
commit 07a2eac
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Showing 2 changed files with 89 additions and 65 deletions.
diff --git a/lib/instrumentation/trace-util.js b/lib/instrumentation/trace-util.js
@@ -1,26 +1,8 @@
 /* eslint-env node */
-const api = require("../api");
-const propagation = require("../propagation");
-
-// returns the header name/value for the first header with a value in the request.
-const getValueFromHeaders = (requestHeaders, headers) => {
-  let value, header;
-
-  for (const h of headers) {
-    let headerValue = requestHeaders[h.toLowerCase()];
-    if (headerValue) {
-      header = h; // source = `${h} http header`;
-      value = headerValue;
-      break;
-    }
-  }
-
-  if (typeof value !== "undefined") {
-    return { value, header };
-  }
-
-  return undefined;
-};
+const api = require("../api"),
+  propagation = require("../propagation"),
+  pkg = require("../../package.json"),
+  debug = require("debug")(`${pkg.name}:event`);
 
 // adds trace source field to the context and returns the updated context
 function _includeSource(context, key) {
@@ -56,16 +38,35 @@ exports.propagateTraceHeader = () => {
 // parse a trace header and return object used to populate args to startTrace
 // deprecated: in the next major version this should get renamed to getSpanContext
 exports.getTraceContext = (traceIdSource, req) => {
-  const { honeycomb, aws } = api;
+  const { honeycomb, w3c, aws } = api;
   if (typeof traceIdSource === "undefined" || typeof traceIdSource === "string") {
-    let headers =
-      typeof traceIdSource === "undefined" ? [honeycomb.TRACE_HTTP_HEADER] : [traceIdSource];
-    let valueAndHeader = getValueFromHeaders(req.headers, headers);
+    let header, value;
+
+    if (typeof traceIdSource !== "undefined") {
+      header = traceIdSource;
+      value = req.headers[traceIdSource.toLowerCase()];
+    } else {
+      const honeycombHeaderValue = req.headers[honeycomb.TRACE_HTTP_HEADER.toLowerCase()];
+      const w3cHeaderValue = req.headers[w3c.TRACE_HTTP_HEADER.toLowerCase()];
+
+      if (honeycombHeaderValue && w3cHeaderValue) {
+        debug("warn: received both honeycomb and w3c propagation headers, preferring honeycomb.");
+      }
 
-    if (!valueAndHeader) {
+      if (honeycombHeaderValue) {
+        header = honeycomb.TRACE_HTTP_HEADER;
+        value = honeycombHeaderValue;
+      } else if (w3cHeaderValue) {
+        header = w3c.TRACE_HTTP_HEADER;
+        value = w3cHeaderValue;
+      }
+    }
+
+    if (!value) {
+      // couldn't find trace context
       return {};
     }
-    let { value, header } = valueAndHeader;
+
     let parsed = {};
     switch (header) {
       //honeycomb trace header
@@ -75,6 +76,12 @@ exports.getTraceContext = (traceIdSource, req) => {
         return _includeSource(parsed, header);
       }
 
+      case w3c.TRACE_HTTP_HEADER: {
+        header = w3c.TRACE_HTTP_HEADER;
+        parsed = w3c.unmarshalTraceContext(value);
+        return _includeSource(parsed, header);
+      }
+
       case aws.TRACE_HTTP_HEADER: {
         header = aws.TRACE_HTTP_HEADER;
         parsed = aws.unmarshalTraceContext(value);

diff --git a/lib/instrumentation/trace-util.test.js b/lib/instrumentation/trace-util.test.js
@@ -10,81 +10,98 @@ function getRequestWithHeader(name, value) {
   return req;
 }
 
+function getRequestWithHeaders(headers) {
+  const req = new http.IncomingMessage();
+  headers.forEach((h) => (req.headers[h.name.toLowerCase()] = h.value));
+  return req;
+}
+
 describe("getTraceContext", () => {
   cases(
-    "AWS X-Ray trace header",
+    "beeline trace header",
     (opts) => {
       expect(
         traceUtil.getTraceContext(
-          "X-Amzn-Trace-Id",
-          getRequestWithHeader("X-Amzn-Trace-Id", opts.headerVal)
+          undefined,
+          getRequestWithHeader(api.honeycomb.TRACE_HTTP_HEADER, opts.headerVal)
         )
       ).toEqual(opts.expectedContext);
     },
     [
       {
-        name: "root / no parent",
-        headerVal: "Root=1-67891233-abcdef012345678912345678",
+        name: "v1 trace_id + parent_id, missing context",
+        headerVal: "1;trace_id=abcdef,parent_id=12345",
         expectedContext: {
-          traceId: "1-67891233-abcdef012345678912345678",
-          parentSpanId: "1-67891233-abcdef012345678912345678",
-          source: "X-Amzn-Trace-Id http header",
+          traceId: "abcdef",
+          parentSpanId: "12345",
+          customContext: undefined,
+          dataset: undefined,
+          source: "X-Honeycomb-Trace http header",
         },
       },
       {
-        name: "root / parent",
-        headerVal: "Root=1-5759e988-bd862e3fe1be46a994272793;Parent=53995c3f42cd8ad8",
-        expectedContext: {
-          traceId: "1-5759e988-bd862e3fe1be46a994272793",
-          parentSpanId: "53995c3f42cd8ad8",
-          source: "X-Amzn-Trace-Id http header",
-        },
+        name: "v1, missing trace_id",
+        contextStr: "1;parent_id=12345",
+        expectedContext: {},
       },
+    ]
+  );
+  cases(
+    "w3c trace header fallback",
+    (opts) => {
+      expect(
+        traceUtil.getTraceContext(
+          undefined,
+          getRequestWithHeader(api.w3c.TRACE_HTTP_HEADER, opts.headerVal)
+        )
+      ).toEqual(opts.expectedContext);
+    },
+    [
       {
-        name: "self / root / no parent",
-        headerVal:
-          "Parent=1-5983f5c9-36d365bc453d28036a63032b;Root=1-5983f5c9-56dcf0bc6d4d214d2dbbe8c6",
+        name: "w3c trace_id + parent_id, missing context",
+        headerVal: "00-7f042f75651d9782dcff93a45fa99be0-c998e73e5420f609-01",
         expectedContext: {
-          parentSpanId: "1-5983f5c9-36d365bc453d28036a63032b",
-          traceId: "1-5983f5c9-56dcf0bc6d4d214d2dbbe8c6",
-          source: "X-Amzn-Trace-Id http header",
+          traceId: "7f042f75651d9782dcff93a45fa99be0",
+          parentSpanId: "c998e73e5420f609",
+          customContext: undefined,
+          dataset: undefined,
+          source: "traceparent http header",
         },
       },
-      {
-        // shouldn't happen at least with aws generated headers, but if we're missing a Root= clause, we aren't in a trace at all.
-        name: "no root / parent",
-        headerVal: "Parent=53995c3f42cd8ad8",
-        expectedContext: {},
-      },
     ]
   );
   cases(
-    "beeline trace header",
+    "if both honeycomb and w3c, choose honeycomb",
     (opts) => {
       expect(
         traceUtil.getTraceContext(
           undefined,
-          getRequestWithHeader(api.honeycomb.TRACE_HTTP_HEADER, opts.headerVal)
+          getRequestWithHeaders([
+            {
+              name: api.w3c.TRACE_HTTP_HEADER,
+              value: opts.w3cHeaderVal,
+            },
+            {
+              name: api.honeycomb.TRACE_HTTP_HEADER,
+              value: opts.beelineHeaderVal,
+            },
+          ])
         )
       ).toEqual(opts.expectedContext);
     },
     [
       {
-        name: "v1 trace_id + parent_id, missing context",
-        headerVal: "1;trace_id=abcdef,parent_id=12345",
+        name: "we got both honeycomb and w3c, this should not happen",
+        w3cHeaderVal: "00-7f042f75651d9782dcff93a45fa99be0-c998e73e5420f609-01",
+        beelineHeaderVal: "1;trace_id=abcdefbeelineahh,parent_id=12345",
         expectedContext: {
-          traceId: "abcdef",
+          traceId: "abcdefbeelineahh",
           parentSpanId: "12345",
           customContext: undefined,
           dataset: undefined,
           source: "X-Honeycomb-Trace http header",
         },
       },
-      {
-        name: "v1, missing trace_id",
-        contextStr: "1;parent_id=12345",
-        expectedContext: {},
-      },
     ]
   );
 });