test: allow FakeAgent to respond to remote config requests

integration-tests/helpers.js

@@ -1,6 +1,8 @@
 'use strict'
 
 const { promisify } = require('util')
+const { createHash } = require('crypto')
+const uuid = require('crypto-randomuuid')
 const express = require('express')
 const bodyParser = require('body-parser')
 const msgpack = require('msgpack-lite')
@@ -24,6 +26,7 @@ class FakeAgent extends EventEmitter {
   constructor (port = 0) {
     super()
     this.port = port
+    this._rc_files = []
   }
 
   async start () {
@@ -38,6 +41,69 @@ class FakeAgent extends EventEmitter {
         payload: msgpack.decode(req.body, { codec })
       })
     })
+    app.post('/v0.7/config', (req, res) => {
+      const buffers = []
+      req.on('data', buffers.push.bind(buffers))
+      req.on('end', () => {
+        const { products } = JSON.parse(Buffer.concat(buffers).toString()).client
+
+        const expires = (new Date(Date.now() + 1000 * 60 * 60 * 24)).toISOString() // in 24 hours
+        const clientID = uuid() // TODO: What is this? It isn't the runtime-id
+
+        // Currently, only `opaque_backend_state` and `targets` are used by dd-trace-js in the object below
+        const targets = {
+          signatures: [],
+          signed: {
+            _type: 'targets',
+            custom: {
+              agent_refresh_interval: 5,
+              opaque_backend_state: ''
+            },
+            expires,
+            spec_version: '1.0.0',
+            targets: {},
+            version: 12345
+          }
+        }
+        const opaqueBackendState = {
+          version: 2,
+          state: { file_hashes: { key: [] } }
+        }
+        const targetFiles = []
+        const clientConfigs = []
+
+        const files = this._rc_files.filter(({ product }) => products.includes(product))
+
+        for (const { orgId, product, id, name, config } of files) {
+          const path = `datadog/${orgId}/${product}/${id}/${name}`
+          const fileDigest = createHash('sha256').update(config).digest()
+
+          opaqueBackendState.state.file_hashes.key.push(fileDigest.toString('base64'))
+
+          targets.signed.targets[path] = {
+            custom: {
+              c: [clientID],
+              'tracer-predicates': { tracer_predicates_v1: [{ clientID }] },
+              v: 20
+            },
+            hashes: { sha256: fileDigest.toString('hex') },
+            length: config.length
+          }
+
+          targetFiles.push({ path, raw: base64(config) })
+          clientConfigs.push(path)
+        }
+
+        targets.signed.custom.opaque_backend_state = base64(opaqueBackendState)
+
+        res.send(JSON.stringify({
+          roots: [], // Not used by dd-trace-js currently
+          targets: base64(targets),
+          target_files: targetFiles,
+          client_configs: clientConfigs
+        }))
+      })
+    })
     app.post('/profiling/v1/input', upload.any(), (req, res) => {
       res.status(200).send()
       this.emit('message', {
@@ -75,6 +141,30 @@ class FakeAgent extends EventEmitter {
     })
   }
 
+  /**
+   * Remove any existing config added by calls to FakeAgent#addRemoteConfig.
+   */
+  resetRemoteConfig () {
+    this._rc_files = []
+  }
+
+  /**
+   * Add a config object to be returned by the fake Remote Config endpoint.
+   * @param {Object} config - Object containing the Remote Config "file" and metadata
+   * @param {number} [config.orgId=2] - The Datadog organization ID
+   * @param {string} config.product - The Remote Config product name
+   * @param {string} config.id - The Remote Config config ID
+   * @param {string} [config.name] - The Remote Config "name". Defaults to the sha256 hash of `config.id`
+   * @param {Object} config.config - The Remote Config "file" object
+   */
+  addRemoteConfig (config) {
+    config.orgId = config.orgId ?? 2
+    config.name = config.name ?? createHash('sha256').update(config.id).digest('hex')
+    config.config = JSON.stringify(config.config)
+
+    this._rc_files.push(config)
+  }
+
   // **resolveAtFirstSuccess** - specific use case for Next.js (or any other future libraries)
   // where multiple payloads are generated, and only one is expected to have the proper span (ie next.request),
   // but it't not guaranteed to be the last one (so, expectedMessageCount would not be helpful).
@@ -486,6 +576,11 @@ function sandboxCwd () {
   return sandbox.folder
 }
 
+function base64 (strOrObj) {
+  const str = typeof strOrObj === 'string' ? strOrObj : JSON.stringify(strOrObj)
+  return Buffer.from(str).toString('base64')
+}
+
 module.exports = {
   FakeAgent,
   spawnProc,