feat: add OpenTelemetry error reporting

.env.example

@@ -12,3 +12,11 @@ RPC_URL_8453=https://example-rpc
 RPC_URL_42161=https://example-rpc
 RPC_URL_80094=https://example-rpc
 RPC_URL_747474=https://example-rpc
+# OpenTelemetry error reporting. Signal-specific values take precedence.
+# Sentry provides the complete OTLP logs endpoint and auth header under Project Settings > Client Keys (DSN).
+OTEL_EXPORTER_OTLP_LOGS_ENDPOINT=
+OTEL_EXPORTER_OTLP_LOGS_HEADERS=
+# Generic OTLP base URL. The worker appends /v1/logs.
+OTEL_EXPORTER_OTLP_ENDPOINT=
+OTEL_EXPORTER_OTLP_HEADERS=
+OTEL_SERVICE_NAME=yearn-prices

.github/workflows/deploy.yml

@@ -38,6 +38,11 @@ jobs:
           RPC_URL_42161: op://webops-prod/yearn-price/RPC_URL_42161
           RPC_URL_80094: op://webops-prod/yearn-price/RPC_URL_80094
           RPC_URL_747474: op://webops-prod/yearn-price/RPC_URL_747474
+          OTEL_EXPORTER_OTLP_ENDPOINT: op://webops-prod/yearn-price/OTEL_EXPORTER_OTLP_ENDPOINT
+          OTEL_EXPORTER_OTLP_HEADERS: op://webops-prod/yearn-price/OTEL_EXPORTER_OTLP_HEADERS
+          OTEL_EXPORTER_OTLP_LOGS_ENDPOINT: op://webops-prod/yearn-price/OTEL_EXPORTER_OTLP_LOGS_ENDPOINT
+          OTEL_EXPORTER_OTLP_LOGS_HEADERS: op://webops-prod/yearn-price/OTEL_EXPORTER_OTLP_LOGS_HEADERS
+          OTEL_SERVICE_NAME: op://webops-prod/yearn-price/OTEL_SERVICE_NAME
       - name: Upload secrets to Cloudflare
         run: |
           jq -n '{
@@ -58,7 +63,12 @@ jobs:
             RPC_URL_8453: env.RPC_URL_8453,
             RPC_URL_42161: env.RPC_URL_42161,
             RPC_URL_80094: env.RPC_URL_80094,
-            RPC_URL_747474: env.RPC_URL_747474
+            RPC_URL_747474: env.RPC_URL_747474,
+            OTEL_EXPORTER_OTLP_ENDPOINT: env.OTEL_EXPORTER_OTLP_ENDPOINT,
+            OTEL_EXPORTER_OTLP_HEADERS: env.OTEL_EXPORTER_OTLP_HEADERS,
+            OTEL_EXPORTER_OTLP_LOGS_ENDPOINT: env.OTEL_EXPORTER_OTLP_LOGS_ENDPOINT,
+            OTEL_EXPORTER_OTLP_LOGS_HEADERS: env.OTEL_EXPORTER_OTLP_LOGS_HEADERS,
+            OTEL_SERVICE_NAME: env.OTEL_SERVICE_NAME
           }' | bunx wrangler secret bulk
       - name: Run migrations
         run: bun run migrate

src/edge-cache.ts

@@ -1,3 +1,6 @@
+import { captureError } from './observability'
+import type { Env } from './types'
+
 // Cloudflare edge caching via the Cache API.
 //
 // A worker-generated Response with a Cache-Control header only drives the
@@ -65,13 +68,24 @@ export async function readEdgeCache(request: Request): Promise<Response | undefi
   return edgeCache().match(cacheKey(request))
 }
 
-export function writeEdgeCache(ctx: ExecutionContext, request: Request, response: Response): void {
+export function writeEdgeCache(
+  ctx: ExecutionContext,
+  env: Env,
+  request: Request,
+  response: Response,
+): void {
   // Trust the Cache API for the store/TTL decision: put() honors the response's
   // Cache-Control — it refuses no-store/private and derives the edge TTL from
   // s-maxage → max-age → Expires. Only success responses reach this function (the
   // request handler returns errors straight from its catch block), so the edge stores
   // successes and nothing else; put() honoring Cache-Control is the backstop.
   //
   // Non-blocking: storing the response must not delay returning it to the client.
-  ctx.waitUntil(edgeCache().put(cacheKey(request), response.clone()))
+  ctx.waitUntil(
+    edgeCache()
+      .put(cacheKey(request), response.clone())
+      .catch((error: unknown) => {
+        captureError(ctx, env, error)
+      }),
+  )
 }

src/index.ts

@@ -5,6 +5,7 @@ import { readEdgeCache, writeEdgeCache } from './edge-cache'
 import { ApiError, jsonError } from './errors'
 import { optionsResponse, withCors } from './http'
 import { renderLandingPage } from './lander'
+import { captureError } from './observability'
 import { handleHealth } from './routes/health'
 import { handleBatchHistorical, handleHistorical, handleRangeHistorical, handleSpot, notFoundErrorHeaders } from './routes/prices'
 import type { Env } from './types'
@@ -88,7 +89,7 @@ export default {
 
       const response = await routePriceRequest(request, env, pathname)
       if (request.method === 'GET') {
-        writeEdgeCache(ctx, request, response)
+        writeEdgeCache(ctx, env, request, response)
       }
       return response
     } catch (error) {
@@ -107,6 +108,7 @@ export default {
         const headers = error.code === 'NOT_FOUND' && notFoundCacheable
           ? withCors(notFoundErrorHeaders())
           : withCors({ 'cache-control': CACHE_CONTROL_NO_STORE })
+        if (error.status >= 500) captureError(ctx, env, error)
         return jsonError(error, headers)
       }
 
@@ -118,6 +120,7 @@ export default {
           error: error instanceof Error ? error.message : String(error),
         }),
       )
+      captureError(ctx, env, error)
       return jsonError(new ApiError('INTERNAL_ERROR', 'Unexpected internal error'), withCors({ 'cache-control': CACHE_CONTROL_NO_STORE }))
     }
   },

src/observability.ts

@@ -0,0 +1,95 @@
+import type { Env } from './types'
+
+// Cloudflare Workers can't run the OpenTelemetry Node SDK, so errors are sent as
+// OTLP/HTTP JSON log records via fetch. Vendor-neutral: point
+// OTEL_EXPORTER_OTLP_ENDPOINT at any OTLP backend (Sentry OTLP, Grafana, a Collector, ...).
+const SERVICE_NAME = 'yearn-prices'
+const SEVERITY_ERROR = 17 // OTLP severityNumber for ERROR
+
+type OtlpAttribute = { key: string; value: { stringValue: string } }
+
+function attr(key: string, value: string): OtlpAttribute {
+  return { key, value: { stringValue: value } }
+}
+
+function decodeHeaderPart(value: string): string {
+  try {
+    return decodeURIComponent(value)
+  } catch {
+    return value
+  }
+}
+
+// OTEL_EXPORTER_OTLP_HEADERS format: "key1=value1,key2=value2".
+function parseHeaders(raw?: string): Record<string, string> {
+  const headers: Record<string, string> = { 'content-type': 'application/json' }
+  if (!raw) return headers
+  for (const pair of raw.split(',')) {
+    const idx = pair.indexOf('=')
+    if (idx > 0) {
+      headers[decodeHeaderPart(pair.slice(0, idx).trim())] = decodeHeaderPart(
+        pair.slice(idx + 1).trim(),
+      )
+    }
+  }
+  return headers
+}
+
+function buildPayload(serviceName: string, err: Error): unknown {
+  const attributes = [attr('exception.type', err.name), attr('exception.message', err.message)]
+  if (err.stack) attributes.push(attr('exception.stacktrace', err.stack))
+
+  return {
+    resourceLogs: [
+      {
+        resource: { attributes: [attr('service.name', serviceName)] },
+        scopeLogs: [
+          {
+            scope: { name: serviceName },
+            logRecords: [
+              {
+                timeUnixNano: String(BigInt(Date.now()) * 1_000_000n),
+                severityNumber: SEVERITY_ERROR,
+                severityText: 'ERROR',
+                body: { stringValue: err.message },
+                attributes,
+              },
+            ],
+          },
+        ],
+      },
+    ],
+  }
+}
+
+export function captureError(ctx: ExecutionContext, env: Env, error: unknown): void {
+  const logsEndpoint = env.OTEL_EXPORTER_OTLP_LOGS_ENDPOINT
+  const endpoint = logsEndpoint || env.OTEL_EXPORTER_OTLP_ENDPOINT
+  if (!endpoint) return
+
+  const err = error instanceof Error ? error : new Error(String(error))
+  const normalizedEndpoint = endpoint.replace(/\/$/, '')
+  const url = logsEndpoint ? normalizedEndpoint : `${normalizedEndpoint}/v1/logs`
+  const body = JSON.stringify(buildPayload(env.OTEL_SERVICE_NAME || SERVICE_NAME, err))
+
+  // waitUntil lets the export finish after the response is returned (no added latency).
+  ctx.waitUntil(
+    fetch(url, {
+      method: 'POST',
+      headers: parseHeaders(env.OTEL_EXPORTER_OTLP_LOGS_HEADERS || env.OTEL_EXPORTER_OTLP_HEADERS),
+      body,
+    }).then((response) => {
+      if (!response.ok) {
+        console.error(JSON.stringify({
+          message: 'otel-export-error',
+          status: response.status,
+        }))
+      }
+    }).catch((exportError) => {
+      console.error(JSON.stringify({
+        message: 'otel-export-error',
+        error: exportError instanceof Error ? exportError.message : String(exportError),
+      }))
+    }),
+  )
+}

src/types.ts

@@ -12,6 +12,11 @@ export type PriceSource = (typeof SOURCE_PRIORITY)[number]
 export interface Env {
   DATABASE_URL: string
   ENSO_API_KEY?: string
+  OTEL_EXPORTER_OTLP_ENDPOINT?: string
+  OTEL_EXPORTER_OTLP_HEADERS?: string
+  OTEL_EXPORTER_OTLP_LOGS_ENDPOINT?: string
+  OTEL_EXPORTER_OTLP_LOGS_HEADERS?: string
+  OTEL_SERVICE_NAME?: string
   [key: string]: string | undefined
 }
 

test/observability.test.ts

@@ -0,0 +1,136 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { captureError } from '../src/observability'
+import type { Env } from '../src/types'
+
+function context(): ExecutionContext {
+  return { waitUntil: vi.fn() } as unknown as ExecutionContext
+}
+
+async function pending(ctx: ExecutionContext): Promise<void> {
+  await (ctx.waitUntil as ReturnType<typeof vi.fn>).mock.calls[0][0]
+}
+
+describe('captureError', () => {
+  afterEach(() => {
+    vi.unstubAllGlobals()
+    vi.restoreAllMocks()
+  })
+
+  it('uses a signal-specific Sentry endpoint without appending another path', async () => {
+    const fetchMock = vi.fn().mockResolvedValue(new Response(null, { status: 200 }))
+    vi.stubGlobal('fetch', fetchMock)
+    const ctx = context()
+    const env = {
+      DATABASE_URL: 'postgres://x',
+      OTEL_EXPORTER_OTLP_LOGS_ENDPOINT: 'https://o0.ingest.sentry.io/api/0/integration/otlp/v1/logs',
+      OTEL_EXPORTER_OTLP_LOGS_HEADERS: 'x-sentry-auth=sentry sentry_key=public-key',
+    } satisfies Env
+
+    captureError(ctx, env, new Error('boom'))
+    await pending(ctx)
+
+    expect(fetchMock).toHaveBeenCalledWith(env.OTEL_EXPORTER_OTLP_LOGS_ENDPOINT, expect.objectContaining({
+      headers: expect.objectContaining({ 'x-sentry-auth': 'sentry sentry_key=public-key' }),
+    }))
+  })
+
+  it('appends the logs path to the generic OTLP base endpoint', async () => {
+    const fetchMock = vi.fn().mockResolvedValue(new Response(null, { status: 200 }))
+    vi.stubGlobal('fetch', fetchMock)
+    const ctx = context()
+
+    captureError(ctx, {
+      DATABASE_URL: 'postgres://x',
+      OTEL_EXPORTER_OTLP_ENDPOINT: 'https://collector.example.test/',
+    }, new Error('boom'))
+    await pending(ctx)
+
+    expect(fetchMock.mock.calls[0][0]).toBe('https://collector.example.test/v1/logs')
+    const payload = JSON.parse(fetchMock.mock.calls[0][1].body as string)
+    expect(payload.resourceLogs[0].scopeLogs[0].logRecords[0].attributes).toEqual(
+      expect.arrayContaining([
+        { key: 'exception.type', value: { stringValue: 'Error' } },
+        { key: 'exception.message', value: { stringValue: 'boom' } },
+      ]),
+    )
+  })
+
+  it('reports rejected exports without throwing into the request path', async () => {
+    vi.stubGlobal('fetch', vi.fn().mockRejectedValue(new Error('socket hang up')))
+    const consoleError = vi.spyOn(console, 'error').mockImplementation(() => {})
+    const ctx = context()
+
+    captureError(ctx, {
+      DATABASE_URL: 'postgres://x',
+      OTEL_EXPORTER_OTLP_ENDPOINT: 'https://collector.example.test',
+    }, new Error('boom'))
+    await pending(ctx)
+
+    expect(consoleError).toHaveBeenCalledWith(expect.stringContaining('otel-export-error'))
+    expect(consoleError).toHaveBeenCalledWith(expect.stringContaining('socket hang up'))
+  })
+
+  it('logs non-2xx export responses without throwing into the request path', async () => {
+    vi.stubGlobal('fetch', vi.fn().mockResolvedValue(new Response(null, { status: 401 })))
+    const consoleError = vi.spyOn(console, 'error').mockImplementation(() => {})
+    const ctx = context()
+
+    captureError(ctx, {
+      DATABASE_URL: 'postgres://x',
+      OTEL_EXPORTER_OTLP_ENDPOINT: 'https://collector.example.test',
+    }, new Error('boom'))
+    await pending(ctx)
+
+    expect(consoleError).toHaveBeenCalledWith(expect.stringContaining('otel-export-error'))
+    expect(consoleError).toHaveBeenCalledWith(expect.stringContaining('401'))
+  })
+
+  it('is a no-op when no OTLP endpoint is configured', () => {
+    const fetchMock = vi.fn()
+    vi.stubGlobal('fetch', fetchMock)
+    const ctx = context()
+
+    captureError(ctx, { DATABASE_URL: 'postgres://x' }, new Error('boom'))
+
+    expect(ctx.waitUntil).not.toHaveBeenCalled()
+    expect(fetchMock).not.toHaveBeenCalled()
+  })
+
+  it('percent-decodes OTLP header values and records an exact unix-nano timestamp', async () => {
+    const fetchMock = vi.fn().mockResolvedValue(new Response(null, { status: 200 }))
+    vi.stubGlobal('fetch', fetchMock)
+    vi.spyOn(Date, 'now').mockReturnValue(1_700_000_000_123)
+    const ctx = context()
+
+    captureError(ctx, {
+      DATABASE_URL: 'postgres://x',
+      OTEL_EXPORTER_OTLP_ENDPOINT: 'https://collector.example.test',
+      OTEL_EXPORTER_OTLP_HEADERS: 'x-custom=foo%2Cbar',
+    }, new Error('boom'))
+    await pending(ctx)
+
+    expect(fetchMock.mock.calls[0][1].headers['x-custom']).toBe('foo,bar')
+    const payload = JSON.parse(fetchMock.mock.calls[0][1].body as string)
+    expect(payload.resourceLogs[0].scopeLogs[0].logRecords[0].timeUnixNano).toBe(
+      String(1_700_000_000_123n * 1_000_000n),
+    )
+  })
+
+  it('does not throw when OTLP headers contain a raw percent', async () => {
+    const fetchMock = vi.fn().mockResolvedValue(new Response(null, { status: 200 }))
+    vi.stubGlobal('fetch', fetchMock)
+    const ctx = context()
+
+    expect(() => {
+      captureError(ctx, {
+        DATABASE_URL: 'postgres://x',
+        OTEL_EXPORTER_OTLP_ENDPOINT: 'https://collector.example.test',
+        OTEL_EXPORTER_OTLP_HEADERS: 'authorization=Api-Key 50%off',
+      }, new Error('boom'))
+    }).not.toThrow()
+
+    await pending(ctx)
+
+    expect(fetchMock.mock.calls[0][1].headers['authorization']).toBe('Api-Key 50%off')
+  })
+})