Cloud Metadata Fetching (#1937)

* Implements: #1815

* feat: cloud metadata request

* chore: move test file

* feat: test complete

* feat: working through test failures

* fix: tests

* chore: re-org

* feat: reorg metadata

* chore: undo test removal

* chore: remove console.log

* feat: request module

* chore: moving on up

* chore: instrumentation path

* chore: bringing over test server fixtures from other branch

* chore: lint cleanup post-elrequest

* fix: failure handlers for request

* chore: lint

* feat: add cli interface for quick testing on cloud servers

* chore: exit codes for cli

* feat: fetch metadata for all, corrdinate messages

* feat: error handling for non-json responses

* feat: adding agent configuration of cloud provider and tests for same

* chore: module constants for timeouts

* ci: new test server endpoint for v2 amazon

* feat: add v2 server tests and implementation

* fix: error handling

* chore: lint

* test: full testing of unexpected responses from metadata server

* chore: lint

* test: tests for coordination object

* chore: rename to CallbackCoordination

* chore: rename library file

* fix: cleanup timeout in coordination

* chore: lint

* fix: better pattern for no double callbacks on errors

* feat: logging, comment proofread

* feat: APM Server wants strings for everything, add type casting/checking

* chore: fix port

* chore: lint

* chore: changelog

* chore: adjust log level

* chore: add link to issue

* chore: nits -- variable name and error type export

* chore: lint, remove unused data

* fix: better pattern for request callback

* chore: variable rename

* chore: change from passing entire agent to just passing provider name

* chore: use logger arg instead of global agent instance

* chore: for loop style

* chore: cast with string objects instead of concats

* chore: not new String, String

* chore: lint

* chore: logger into other tests

* chore: more getLogger calls

* chore: lint

* feat: unified IMDSv1 and IMDSv2 method

* feat: unify aws APIs

* fix: avoid catching the callback's exceptions

* fix: removes instances of "callback function in a try" anti-pattern

* feat: refactor to use URLs, move constants into modules

* fix: 32 is not x32

* chore: lint

* fix: node 8 and URL

* feat: config normalization and testing

* feat: improve API of getMetadata... methods, baseApiOverride param

* fix: log a "shouldn't happen" situation

* chore: update comments

* chore: err vs. error

* chore: no-op logger

* chore: one last logger

* chore: lint

* chore: module path

CHANGELOG.asciidoc

@@ -42,6 +42,13 @@ Notes:
   allow numeric and boolean labels. Stringify defaults to true for backwards
   compatibility -- stringification will be removed in a future major version.
 
+* feat: added support for cloud metadata fetching
+  Implements: https://github.com/elastic/apm-agent-nodejs/issues/1815
+
+  Agent now collects information about its cloud environment and includes this data in the APM Server's metadata payload.  See
+  https://github.com/elastic/apm/blob/3acd10afa0a9d3510e819229dfce0764133083d3/specs/agents/metadata.md#cloud-provider-metadata
+  for more information.
+
 [float]
 ===== Bug fixes
 

lib/cloud-metadata/aws.js

@@ -0,0 +1,159 @@
+'use strict'
+const URL = require('url').URL
+const { httpRequest } = require('../http-request')
+const DEFAULT_BASE_URL = new URL('/', 'http://169.254.169.254:80')
+
+function sanitizeHttpHeaderValue (value) {
+  // no newlines, carriage returns, or ascii characters outside of 32 (\x20) - 127 (\x7F)
+  const newValue = value.replace(/[\r\n]/g, '').replace(/[^\x20-\x7F]/g, '')
+  return newValue
+}
+
+/**
+ * Logic for making request to /latest/dynamic/instance-identity/document
+ *
+ * The headers parameter allow us to, if needed, set the IMDSv2 token
+ */
+function getMetadataAwsWithHeaders (baseUrl, headers, connectTimeoutMs, resTimeoutMs, logger, cb) {
+  const options = {
+    method: 'GET',
+    timeout: resTimeoutMs,
+    connectTimeout: connectTimeoutMs
+  }
+  if (headers) {
+    options.headers = headers
+  }
+  const url = baseUrl + 'latest/dynamic/instance-identity/document'
+  const req = httpRequest(
+    url,
+    options,
+    function (res) {
+      const finalData = []
+      res.on('data', function (data) {
+        finalData.push(data)
+      })
+
+      res.on('end', function (data) {
+        let result
+        try {
+          result = formatMetadataStringIntoObject(finalData.join(''))
+        } catch (err) {
+          logger.trace('aws metadata server responded, but there was an ' +
+            'error parsing the result: %o', err)
+          cb(err)
+          return
+        }
+        cb(null, result)
+      })
+    }
+  )
+
+  req.on('timeout', function () {
+    req.destroy(new Error('request to metadata server timed out'))
+  })
+
+  req.on('connectTimeout', function () {
+    req.destroy(new Error('could not ping metadata server'))
+  })
+
+  req.on('error', function (err) {
+    cb(err)
+  })
+
+  req.end()
+}
+
+/**
+ * Fetches metadata from either an IMDSv2 or IMDSv1 endpoint
+ *
+ * Attempts to fetch a token for an IMDSv2 service call.  If this call
+ * is a success, then we call the instance endpoint with the token.  If
+ * this call fails, then we call the instance endpoint without the token.
+ *
+ * A "success" to the token endpoint means an HTTP status code of 200
+ * and a non-zero-length return value for the token.
+ *
+ * https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-identity-documents.html
+ */
+function getMetadataAws (connectTimeoutMs, resTimeoutMs, logger, baseUrlOverride, cb) {
+  const baseUrl = baseUrlOverride || DEFAULT_BASE_URL
+  const url = baseUrl + 'latest/api/token'
+  const options = {
+    method: 'PUT',
+    headers: {
+      'X-aws-ec2-metadata-token-ttl-seconds': 300
+    },
+    timeout: resTimeoutMs,
+    connectTimeout: connectTimeoutMs
+  }
+  const req = httpRequest(
+    url,
+    options,
+    function (res) {
+      const finalData = []
+      res.on('data', function (data) {
+        finalData.push(data)
+      })
+
+      res.on('end', function () {
+        const token = sanitizeHttpHeaderValue(finalData.join(''))
+        const headers = {}
+        if (token && res.statusCode === 200) {
+          // uses return value from call to latest/api/token as token,
+          // and takes extra steps to ensure characters are valid
+          headers['X-aws-ec2-metadata-token'] = token
+        }
+
+        getMetadataAwsWithHeaders(
+          baseUrl,
+          headers,
+          connectTimeoutMs,
+          resTimeoutMs,
+          logger,
+          cb
+        )
+      })
+    }
+  )
+  req.on('timeout', function () {
+    req.destroy(new Error('request for metadata token timed out'))
+  })
+
+  req.on('connectTimeout', function () {
+    req.destroy(new Error('socket connection to metadata token server timed out'))
+  })
+
+  req.on('error', function (err) {
+    cb(err)
+  })
+
+  req.end()
+}
+
+/**
+ * Builds metadata object
+ *
+ * Takes the response from a /latest/dynamic/instance-identity/document
+ * service request and formats it into the cloud metadata object
+ */
+function formatMetadataStringIntoObject (string) {
+  const data = JSON.parse(string)
+  const metadata = {
+    account: {
+      id: String(data.accountId)
+    },
+    instance: {
+      id: String(data.instanceId)
+    },
+    availability_zone: String(data.availabilityZone),
+    machine: {
+      type: String(data.instanceType)
+    },
+    provider: 'aws',
+    region: String(data.region)
+  }
+
+  return metadata
+}
+
+module.exports = { getMetadataAws }

lib/cloud-metadata/azure.js

@@ -0,0 +1,112 @@
+'use strict'
+const URL = require('url').URL
+const { httpRequest } = require('../http-request')
+
+const DEFAULT_BASE_URL = new URL('/', 'http://169.254.169.254:80')
+
+/**
+ * Checks for metadata server then fetches data
+ *
+ * The getMetadataAzure method will fetch cloud metadata information
+ * from Amazon's IMDSv1 endpoint and return (via callback)
+ * the formatted metadata.
+ *
+ * Before fetching data, the server will be "pinged" by attempting
+ * to connect via TCP with a short timeout (`connectTimeoutMs`).
+ *
+ * https://docs.microsoft.com/en-us/azure/virtual-machines/windows/instance-metadata-service?tabs=windows
+ */
+function getMetadataAzure (connectTimeoutMs, resTimeoutMs, logger, baseUrlOverride, cb) {
+  const baseUrl = baseUrlOverride || DEFAULT_BASE_URL
+  const options = {
+    method: 'GET',
+    timeout: resTimeoutMs,
+    connectTimeout: connectTimeoutMs,
+    headers: {
+      Metadata: 'true'
+    }
+  }
+
+  const url = baseUrl.toString() + 'metadata/instance?api-version=2020-09-01'
+
+  const req = httpRequest(
+    url,
+    options,
+    function (res) {
+      const finalData = []
+      res.on('data', function (data) {
+        finalData.push(data)
+      })
+
+      res.on('end', function (data) {
+        let result
+        try {
+          result = formatMetadataStringIntoObject(finalData.join(''))
+        } catch (err) {
+          logger.trace('azure metadata server responded, but there was an ' +
+            'error parsing the result: %o', err)
+          cb(err)
+          return
+        }
+        cb(null, result)
+      })
+    }
+  )
+
+  req.on('timeout', function () {
+    req.destroy(new Error('request to azure metadata server timed out'))
+  })
+
+  req.on('connectTimeout', function () {
+    req.destroy(new Error('could not ping azure metadata server'))
+  })
+
+  req.on('error', function (err) {
+    cb(err)
+  })
+
+  req.end()
+}
+
+/**
+ * Builds metadata object
+ *
+ * Takes the response from /metadata/instance?api-version=2020-09-01
+ * service request and formats it into the cloud metadata object
+ */
+function formatMetadataStringIntoObject (string) {
+  const metadata = {
+    account: {
+      id: null
+    },
+    instance: {
+      id: null,
+      name: null
+    },
+    project: {
+      name: null
+    },
+    availability_zone: null,
+    machine: {
+      type: null
+    },
+    provider: 'azure',
+    region: null
+  }
+  const parsed = JSON.parse(string)
+  if (!parsed.compute) {
+    return metadata
+  }
+  const data = parsed.compute
+  metadata.account.id = String(data.subscriptionId)
+  metadata.instance.id = String(data.vmId)
+  metadata.instance.name = String(data.name)
+  metadata.project.name = String(data.resourceGroupName)
+  metadata.availability_zone = String(data.zone)
+  metadata.machine.type = String(data.vmSize)
+  metadata.region = String(data.location)
+
+  return metadata
+}
+
+module.exports = { getMetadataAzure }