add cf tracing docs

sending-data/opentelemetry/cloudflare.md

@@ -0,0 +1,113 @@
+---
+order: 0
+label: Cloudflare
+---
+
+# OpenTelemetry for Cloudflare Workers
+
+Instrument your [Cloudflare Worker](https://developers.cloudflare.com/workers/) applications with [OpenTelemetry](https://opentelemetry.io/) using the the [otel-cf-workers](https://github.com/evanderkoogh/otel-cf-workers).
+
+---
+
+
+## Instrumentation
+
+### Step 1: Install the SDK
+
+
+Install `@microlabs/otel-cf-workers` in your project.
+
+```bash # :icon-terminal: terminal
+npm i @microlabs/otel-cf-workers 
+```
+
+### Step 2: Configure the tracer
+
+Create a file `instrumentation.ts` in the root of your project and add the following code to configure and initialize OpenTelemetry.
+
+
+```typescript # :icon-code: index.ts
+import { instrument, ResolveConfigFn } from '@microlabs/otel-cf-workers'
+
+export interface Env {
+	BASELIME_KEY: string
+    SERVICE_NAME: string
+}
+
+const handler = {
+	async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
+		// your cloudflare worker code
+	},
+}
+
+const config: ResolveConfigFn = (env: Env, _trigger) => {
+	return {
+		exporter: {
+			url: 'https://otel.baselime.io/v1,
+			headers: { 'x-honeycomb-team': env.BASELIME_KEY },
+		},
+		service: { name: env.SERVICE_NAME },
+	}
+}
+
+export default instrument(handler, config)
+```
+
+### Step 3: Set the Baselime environment variables
+
+In your `wrangler.toml` file set the `BASELIME_KEY` and `SERVICE_NAME` variables
+
+!!!
+Get your pulic BASELIME_KEY from the [Baselime console](https://console.baselime.io).
+!!!
+
+```toml # :icon-code: wrangler.toml
+[vars]
+
+BASELIME_KEY = "your api key"
+SERVICE_NAME = "pokedex"
+```
+
+Once these steps are completed, distributed traces from your Next.js applications should be available in Baselime to query via the console or the Baselime CLI.
+
+![Example Cloudflare Trace](../../assets/images/illustrations/sending-data/opentelemetry/cf-tracing.png)
+
+---
+
+## Adding custom OpenTelemetry spans
+
+To add custom spans to your OpenTelemetry traces, install the `@opentelemetry/api` package.
+
+```bash # :icon-terminal: terminal
+npm i @opentelemetry/api
+```
+
+And manually add spans to your traces.
+
+```typescript # :icon-code: page.js
+import { trace } from "@opentelemetry/api";
+
+const tracer = trace.getTracer('your-custom-traces');
+
+const handler = {
+    async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
+        const span = trace.getActiveSpan();
+
+        span.setAttribute('search', search)
+
+        const result = await tracer.startActiveSpan(`business-logic`, async (span) => {
+            // your business logic
+            const input = { search }
+            span.setAttributes(input);
+            const result = await yourBusinessLogic(input)
+            span.setAttributes(result)
+            return result
+        });
+    }
+}
+```
+---
+
+## Special Thanks
+
+This is powered by [otel-cf-workers](https://github.com/evanderkoogh/otel-cf-workers) developed by [Erwin van der Koogh](https://github.com/evanderkoogh). It's a fantastic vendor agnostic OpenTelemetry SDK for Cloudflare Workers and you should check it out.