Add runtime guardrail for SSI

When in SSI, bail out if our version of Node.js is incompatible.

init.js

@@ -22,6 +22,17 @@ if (process.env.DD_INJECTION_ENABLED) {
       initBailout = true
     }
   }
+
+  // If we're running via single-step install, and the runtime doesn't match
+  // the engines field in package.json, then we should not initialize the tracer.
+  if (!initBailout) {
+    const { engines } = require('./package.json')
+    const version = process.versions.node
+    const semver = require('semver')
+    if (!semver.satisfies(version, engines.node)) {
+      initBailout = true
+    }
+  }
 }
 
 if (!initBailout) {

integration-tests/init.spec.js

@@ -36,22 +36,45 @@ describe('init.js', () => {
     return sandbox.remove()
   })
 
-  context('when dd-trace is not in the app dir', () => {
-    const NODE_OPTIONS = `--require ${path.join(__dirname, '..', 'init.js')}`
-    it('should initialize the tracer, if no DD_INJECTION_ENABLED', () => {
-      return runTest(cwd, { NODE_OPTIONS }, 'true\n')
+  context('preferring app-dir dd-trace', () => {
+    context('when dd-trace is not in the app dir', () => {
+      const NODE_OPTIONS = `--require ${path.join(__dirname, '..', 'init.js')}`
+      it('should initialize the tracer, if no DD_INJECTION_ENABLED', () => {
+        return runTest(cwd, { NODE_OPTIONS }, 'true\n')
+      })
+      it('should not initialize the tracer, if DD_INJECTION_ENABLED', () => {
+        return runTest(cwd, { NODE_OPTIONS, DD_INJECTION_ENABLED }, 'false\n')
+      })
     })
-    it('should not initialize the tracer, if DD_INJECTION_ENABLED', () => {
-      return runTest(cwd, { NODE_OPTIONS, DD_INJECTION_ENABLED }, 'false\n')
+    context('when dd-trace in the app dir', () => {
+      const NODE_OPTIONS = '--require dd-trace/init.js'
+      it('should initialize the tracer, if no DD_INJECTION_ENABLED', () => {
+        return runTest(cwd, { NODE_OPTIONS }, 'true\n')
+      })
+      it('should initialize the tracer, if DD_INJECTION_ENABLED', () => {
+        return runTest(cwd, { NODE_OPTIONS, DD_INJECTION_ENABLED }, 'true\n')
+      })
     })
   })
-  context('when dd-trace in the app dir', () => {
-    const NODE_OPTIONS = '--require dd-trace/init.js'
-    it('should initialize the tracer, if no DD_INJECTION_ENABLED', () => {
-      return runTest(cwd, { NODE_OPTIONS }, 'true\n')
+  context('runtime version check', () => {
+    const NODE_OPTIONS = `--require ${path.join(__dirname, 'init', 'setversion.js')} --require dd-trace/init.js`
+    context('when node version is less than engines field', () => {
+      const FAKE_VERSION = '3.0.0'
+      it('should initialize the tracer, if no DD_INJECTION_ENABLED', () => {
+        return runTest(cwd, { NODE_OPTIONS, FAKE_VERSION }, 'true\n')
+      })
+      it('should not initialize the tracer, if DD_INJECTION_ENABLED', () => {
+        return runTest(cwd, { NODE_OPTIONS, DD_INJECTION_ENABLED, FAKE_VERSION }, 'false\n')
+      })
     })
-    it('should initialize the tracer, if DD_INJECTION_ENABLED', () => {
-      return runTest(cwd, { NODE_OPTIONS, DD_INJECTION_ENABLED }, 'true\n')
+    context('when node version is more than engines field', () => {
+      const FAKE_VERSION = '50000.0.0'
+      it('should initialize the tracer, if no DD_INJECTION_ENABLED', () => {
+        return runTest(cwd, { NODE_OPTIONS, FAKE_VERSION }, 'true\n')
+      })
+      it('should initialize the tracer, if DD_INJECTION_ENABLED', () => {
+        return runTest(cwd, { NODE_OPTIONS, DD_INJECTION_ENABLED, FAKE_VERSION }, 'true\n')
+      })
     })
   })
 })

integration-tests/init/setversion.js

@@ -0,0 +1,7 @@
+'use strict'
+
+const desc = Reflect.getOwnPropertyDescriptor(process.versions, 'node')
+
+desc.value = process.env.FAKE_VERSION
+
+Reflect.defineProperty(process.versions, 'node', desc)