fix support for environment variable

Author: rochdev

packages/dd-trace/src/plugin_manager.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const { channel } = require('dc-polyfill')
-const { isFalse, normalizePluginEnvName } = require('./util')
+const { isFalse, isTrue, normalizePluginEnvName } = require('./util')
 const plugins = require('./plugins')
 const log = require('./log')
 const { getEnvironmentVariable } = require('../../dd-trace/src/config-helper')
@@ -32,8 +32,7 @@ loadChannel.subscribe(({ name }) => {
 function maybeEnable (Plugin) {
   if (!Plugin || typeof Plugin !== 'function') return
   if (!pluginClasses[Plugin.id]) {
-    const envName = `DD_TRACE_${Plugin.id.toUpperCase()}_ENABLED`
-    const enabled = getEnvironmentVariable(normalizePluginEnvName(envName))
+    const enabled = getEnvEnabled(Plugin)
 
     // TODO: remove the need to load the plugin class in order to disable the plugin
     if (isFalse(enabled) || disabledPlugins.has(Plugin.id)) {
@@ -46,6 +45,11 @@ function maybeEnable (Plugin) {
   }
 }
 
+function getEnvEnabled (Plugin) {
+  const envName = `DD_TRACE_${Plugin.id.toUpperCase()}_ENABLED`
+  return getEnvironmentVariable(normalizePluginEnvName(envName))
+}
+
 // TODO this must always be a singleton.
 module.exports = class PluginManager {
   constructor (tracer) {
@@ -74,7 +78,7 @@ module.exports = class PluginManager {
       this._pluginsByName[name] = new Plugin(this._tracer, this._tracerConfig)
     }
     const pluginConfig = this._configsByName[name] || {
-      enabled: this._tracerConfig.plugins !== false && !Plugin.experimental
+      enabled: isTrue(getEnvEnabled(Plugin)) || (this._tracerConfig.plugins !== false && !Plugin.experimental)
     }
 
     // extracts predetermined configuration from tracer and combines it with plugin-specific config

packages/dd-trace/test/plugin_manager.spec.js

@@ -91,6 +91,7 @@ describe('Plugin Manager', () => {
 
   afterEach(() => {
     delete process.env.DD_TRACE_DISABLED_PLUGINS
+    delete process.env.DD_TRACE_EIGHT_ENABLED
     pm.destroy()
   })
 
@@ -287,6 +288,20 @@ describe('Plugin Manager', () => {
         loadChannel.publish({ name: 'eight' })
         expect(Eight.prototype.configure).to.have.been.calledWithMatch({ enabled: false })
       })
+
+      it('should enable the plugin when configured programmatically', () => {
+        pm.configure()
+        pm.configurePlugin('eight')
+        loadChannel.publish({ name: 'eight' })
+        expect(Eight.prototype.configure).to.have.been.calledWithMatch({ enabled: true })
+      })
+
+      it('should enable the plugin when configured with an environment variable', () => {
+        process.env.DD_TRACE_EIGHT_ENABLED = 'true'
+        pm.configure()
+        loadChannel.publish({ name: 'eight' })
+        expect(Eight.prototype.configure).to.have.been.calledWithMatch({ enabled: true })
+      })
     })
 
     it('instantiates plugin classes', () => {