feat: OpenTelemetry Tracing API and Exporting (#26710)

Initial import of OTEL code supporting tracing. Metrics soon to come.
Implements APIs for https://jsr.io/@deno/otel so that code using
OpenTelemetry.js just works tm.

There is still a lot of work to do with configuration and adding
built-in tracing to core APIs, which will come in followup PRs.

---------

Co-authored-by: Luca Casonato <hello@lcas.dev>

4 files changed, 104 insertions, 0 deletions

diff --git a/tests/specs/cli/otel_basic/__test__.jsonc b/tests/specs/cli/otel_basic/__test__.jsonc
new file mode 100644
index 000000000..a9d4fff04
--- /dev/null
+++ b/tests/specs/cli/otel_basic/__test__.jsonc
@@ -0,0 +1,4 @@
+{
+  "args": "run -A main.ts",
+  "output": "processed\n"
+}
diff --git a/tests/specs/cli/otel_basic/child.ts b/tests/specs/cli/otel_basic/child.ts
new file mode 100644
index 000000000..72cffd9f0
--- /dev/null
+++ b/tests/specs/cli/otel_basic/child.ts
@@ -0,0 +1,20 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+async function inner() {
+  using _span = new Deno.tracing.Span("inner span");
+  console.log("log 1");
+  await 1;
+  console.log("log 2");
+}
+
+Deno.serve({
+  port: 0,
+  onListen({ port }) {
+    console.log(port.toString());
+  },
+  handler: async (_req) => {
+    using _span = new Deno.tracing.Span("outer span");
+    await inner();
+    return new Response(null, { status: 200 });
+  },
+});
diff --git a/tests/specs/cli/otel_basic/deno.json b/tests/specs/cli/otel_basic/deno.json
new file mode 100644
index 000000000..105514e13
--- /dev/null
+++ b/tests/specs/cli/otel_basic/deno.json
@@ -0,0 +1,4 @@
+{
+  "lock": false,
+  "importMap": "../../../../import_map.json"
+}
diff --git a/tests/specs/cli/otel_basic/main.ts b/tests/specs/cli/otel_basic/main.ts
new file mode 100644
index 000000000..66ef5c79c
--- /dev/null
+++ b/tests/specs/cli/otel_basic/main.ts
@@ -0,0 +1,76 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { assert, assertEquals } from "@std/assert";
+import { TextLineStream } from "@std/streams/text-line-stream";
+
+const logs = [];
+const spans = [];
+let child: Deno.ChildProcess;
+
+Deno.serve(
+  {
+    port: 0,
+    async onListen({ port }) {
+      const command = new Deno.Command(Deno.execPath(), {
+        args: ["run", "-A", "--unstable-otel", "child.ts"],
+        env: {
+          OTEL_EXPORTER_OTLP_PROTOCOL: "http/json",
+          OTEL_EXPORTER_OTLP_ENDPOINT: `http://localhost:${port}`,
+          OTEL_BSP_SCHEDULE_DELAY: "10",
+          OTEL_BLRP_SCHEDULE_DELAY: "10",
+        },
+        stdin: "piped",
+        stdout: "piped",
+        stderr: "inherit",
+      });
+      child = command.spawn();
+      const lines = child.stdout
+        .pipeThrough(new TextDecoderStream())
+        .pipeThrough(new TextLineStream())
+        .getReader();
+      const line = await lines.read();
+      await fetch(`http://localhost:${line.value}/`);
+    },
+    async handler(req) {
+      try {
+        const body = await req.json();
+        if (body.resourceLogs) {
+          logs.push(...body.resourceLogs[0].scopeLogs[0].logRecords);
+        }
+        if (body.resourceSpans) {
+          spans.push(...body.resourceSpans[0].scopeSpans[0].spans);
+        }
+
+        if (logs.length > 2 && spans.length > 1) {
+          child.kill();
+
+          const inner = spans.find((s) => s.name === "inner span");
+          const outer = spans.find((s) => s.name === "outer span");
+
+          assertEquals(inner.traceId, outer.traceId);
+          assertEquals(inner.parentSpanId, outer.spanId);
+
+          assertEquals(logs[1].body.stringValue, "log 1\n");
+          assertEquals(logs[1].traceId, inner.traceId);
+          assertEquals(logs[1].spanId, inner.spanId);
+
+          assertEquals(logs[2].body.stringValue, "log 2\n");
+          assertEquals(logs[2].traceId, inner.traceId);
+          assertEquals(logs[2].spanId, inner.spanId);
+
+          console.log("processed");
+          Deno.exit(0);
+        }
+
+        return Response.json({ partialSuccess: {} }, { status: 200 });
+      } catch (e) {
+        console.error(e);
+        Deno.exit(1);
+      }
+    },
+  },
+);
+
+setTimeout(() => {
+  assert(false, "test did not finish in time");
+}, 10e3);