feat: opentelemetry integration

docs/integrations/README.md

@@ -4,3 +4,4 @@
 
 - [@nexus/schema](/docs/integrations/nexus-schema.md) - Declarative, code-first and strongly typed GraphQL schema construction for TypeScript & JavaScript
 - [mercurius-integration-testing](/docs/integrations/mercurius-integration-testing.md) - Utility library for writing mercurius integration tests.
+- [@opentelemetry](/docs/integrations/open-telemetry) - A framework for collecting traces and metrics from applications.

docs/integrations/open-telemetry.md

@@ -0,0 +1,141 @@
+# mercurius
+
+## OpenTelemetry (Tracing)
+
+Mercurius is compatible with open-telemetry
+
+
+## Example
+
+Here is a simple exemple on how to enable tracing on Mercurius with OpenTelemetry:
+
+tracer.js
+```js
+'use strict'
+
+const api = require('@opentelemetry/api')
+const { NodeTracerProvider } = require('@opentelemetry/node')
+const { SimpleSpanProcessor } = require('@opentelemetry/tracing')
+const { JaegerExporter } = require('@opentelemetry/exporter-jaeger')
+const { GraphQLInstrumentation } = require('@opentelemetry/instrumentation-graphql')
+const { HttpTraceContext } = require('@opentelemetry/core')
+const { ZipkinExporter } = require('@opentelemetry/exporter-zipkin')
+// or
+// const { JaegerExporter } = require('@opentelemetry/exporter-jaeger')
+
+module.exports = serviceName => {
+  const provider = new NodeTracerProvider()
+  const graphQLInstrumentation = new GraphQLInstrumentation()
+  graphQLInstrumentation.setTracerProvider(provider)
+  graphQLInstrumentation.enable()
+
+  api.propagation.setGlobalPropagator(new HttpTraceContext())
+  api.trace.setGlobalTracerProvider(provider)
+
+  provider.addSpanProcessor(
+    new SimpleSpanProcessor(
+      new ZipkinExporter({
+        serviceName
+      })
+      // or 
+      // new JaegerExporter({
+      //   serviceName,
+      // })
+    )
+  )
+  provider.register()
+  return provider
+}
+```
+
+serviceAdd.js
+```js
+'use strict'
+// Register tracer
+const serviceName = 'service-add'
+const tracer = require('./tracer')
+tracer(serviceName)
+
+const service = require('fastify')({ logger: { level: 'debug' } })
+const mercurius = require('mercurius')
+const opentelemetry = require('@autotelic/fastify-opentelemetry')
+
+service.register(opentelemetry, { serviceName })
+service.register(mercurius, {
+  schema: `
+  extend type Query {
+    add(x: Float, y: Float): Float
+  }
+  `,
+  resolvers: {
+    Query: {
+      add: (_, { x, y }, { reply }) => {
+        const { activeSpan, tracer } = reply.request.openTelemetry()
+
+        activeSpan.setAttribute('arg.x', x)
+        activeSpan.setAttribute('arg.y', y)
+
+        const span = tracer.startSpan('compute-add', { parent: tracer.getCurrentSpan() })
+        const result = x + y
+        span.end()
+
+        return result
+      }
+    }
+  },
+  federationMetadata: true
+})
+
+service.listen(4001, 'localhost', err => {
+  if (err) {
+    console.error(err)
+    process.exit(1)
+  }
+})
+```
+
+gateway.js
+```js
+'use strict'
+const serviceName = 'gateway'
+const tracer = require('./tracer')
+// Register tracer
+tracer(serviceName)
+
+const gateway = require('fastify')({ logger: { level: 'debug' } })
+const mercurius = require('mercurius')
+const opentelemetry = require('@autotelic/fastify-opentelemetry')
+
+// Register fastify opentelemetry
+gateway.register(opentelemetry, { serviceName })
+gateway.register(mercurius, {
+  gateway: {
+    services: [
+      {
+        name: 'add',
+        url: 'http://localhost:4001/graphql'
+      }
+    ]
+  }
+})
+
+gateway.listen(3000, 'localhost', err => {
+  if (err) {
+    process.exit(1)
+  }
+})
+```
+
+Start a zipkin service:
+
+```
+$ docker run -d -p 9411:9411 openzipkin/zipkin
+```
+
+Send some request to the gateway: 
+
+```bash
+$ curl localhost:3000/graphql -H 'Content-Type: application/json' --data '{"query":"{ add(x: 1, y: 2) }"}'
+```
+
+You can now browse through mercurius tracing at `http://localhost:9411`

docsify/sidebar.md

@@ -19,6 +19,7 @@
 * [Integrations](/docs/integrations/)
   * [@nexus/schema](/docs/integrations/nexus-schema)
   * [Testing](/docs/integrations/mercurius-integration-testing)
+  * [Tracing - OpenTelemetry](/docs/integrations/open-telemetry)
 * [Related plugins](/docs/plugins)
   * [mercurius-upload](/docs/plugins#mercurius-upload)
   * [altair-fastify-plugin](/docs/plugins#altair-fastify-plugin)

index.js

@@ -37,6 +37,7 @@ const {
   MER_ERR_INVALID_OPTS,
   MER_ERR_METHOD_NOT_ALLOWED
 } = require('./lib/errors')
+const tracer = require('./lib/tracer')
 
 const kLoaders = Symbol('mercurius.loaders')
 const kFactory = Symbol('mercurius.loadersFactory')
@@ -373,12 +374,15 @@ const plugin = fp(async function (app, opts) {
   }
 
   async function fastifyGraphQl (source, context, variables, operationName) {
+    const span = tracer.startSpan('mercurius - graphql', { parent: tracer.getCurrentSpan() })
+
     context = Object.assign({ app: this, lruGatewayResolvers }, context)
     const reply = context.reply
 
     // Parse, with a little lru
     const cached = lru !== null && lru.get(source)
     let document = null
+    span.setAttribute('mercurius.cached', !!cached)
     if (!cached) {
       // We use two caches to avoid errors bust the good
       // cache. This is a protection against DoS attacks
@@ -388,6 +392,7 @@ const plugin = fp(async function (app, opts) {
         // this query errored
         const err = new MER_ERR_GQL_VALIDATION()
         err.errors = cachedError.validationErrors
+        span.end()
         throw err
       }
 
@@ -396,6 +401,7 @@ const plugin = fp(async function (app, opts) {
       } catch (syntaxError) {
         const err = new MER_ERR_GQL_VALIDATION()
         err.errors = [syntaxError]
+        span.end()
         throw err
       }
 
@@ -416,6 +422,7 @@ const plugin = fp(async function (app, opts) {
         }
         const err = new MER_ERR_GQL_VALIDATION()
         err.errors = validationErrors
+        span.end()
         throw err
       }
 
@@ -425,6 +432,7 @@ const plugin = fp(async function (app, opts) {
         if (queryDepthErrors.length > 0) {
           const err = new MER_ERR_GQL_VALIDATION()
           err.errors = queryDepthErrors
+          span.end()
           throw err
         }
       }
@@ -442,6 +450,7 @@ const plugin = fp(async function (app, opts) {
       if (operationAST.operation !== 'query') {
         const err = new MER_ERR_METHOD_NOT_ALLOWED()
         err.errors = [new Error('Operation cannot be performed via a GET request')]
+        span.end()
         throw err
       }
     }
@@ -453,8 +462,9 @@ const plugin = fp(async function (app, opts) {
 
     if (cached && cached.jit !== null) {
       const execution = await cached.jit.query(root, context, variables || {})
-
-      return maybeFormatErrors(execution, context)
+      const resWithFormatedErrors = maybeFormatErrors(execution, context)
+      span.end()
+      return resWithFormatedErrors
     }
 
     // Validate variables
@@ -463,6 +473,7 @@ const plugin = fp(async function (app, opts) {
       if (Array.isArray(executionContext)) {
         const err = new MER_ERR_GQL_VALIDATION()
         err.errors = executionContext
+        span.end()
         throw err
       }
     }
@@ -476,7 +487,9 @@ const plugin = fp(async function (app, opts) {
       operationName
     )
 
-    return maybeFormatErrors(execution, context)
+    const resWithFormatedErrors = maybeFormatErrors(execution, context)
+    span.end()
+    return resWithFormatedErrors
   }
 
   function maybeFormatErrors (execution, context) {

lib/tracer.js

@@ -0,0 +1,5 @@
+'use strict'
+const api = require('@opentelemetry/api')
+const meta = require('../package.json')
+
+module.exports = api.trace.getTracer(meta.name, meta.version)

package.json

@@ -28,6 +28,7 @@
     "@graphql-tools/merge": "^6.2.4",
     "@graphql-tools/schema": "^6.2.4",
     "@graphql-tools/utils": "^6.2.4",
+    "@opentelemetry/api": "0.11.0",
     "@sinonjs/fake-timers": "^6.0.1",
     "@types/node": "^14.0.23",
     "@types/ws": "^7.2.6",