[#371] Add ConfigurationBuilder for flexible config management

Author: feelform

lib/config.js

@@ -337,6 +337,70 @@ function registerLoadedConfig(propertyName, callback) {
   loadedConfigCallbacks.push({ propertyName, callback })
 }
 
+class Config {
+  constructor(config) {
+    Object.assign(this, config)
+    Object.freeze(this)
+  }
+}
+
+class ConfigBuilder {
+  constructor(agentStartupUserDefinedJson = {}) {
+    this.agentStartupUserDefinedJson = agentStartupUserDefinedJson
+  }
+
+  setDefaultJson(json) {
+    this.defaultJson = json
+    return this
+  }
+
+  setUserDefinedJson(json) {
+    this.userDefinedJson = json
+    return this
+  }
+
+  build() {
+    if (!this.defaultJson) {
+      this.defaultJson = require('./pinpoint-config-default')
+    }
+
+    if (!this.userDefinedJson) {
+      this.userDefinedJson = readRootConfigFile()
+    }
+
+    const config = Object.assign({},
+      readConfigJson(this.defaultJson),
+      readConfigJson(this.userDefinedJson),
+      readFromEnv(),
+      readConfigJson(this.agentStartupUserDefinedJson))
+
+    Object.entries(REQUIRE_CONFIG).forEach(([propertyName, description]) => {
+      if (propertyName === 'agentId' && !config[propertyName]) {
+        return config.agentId = randomBytes(8).toString('hex')
+      }
+      if (config.enable && !config[propertyName]) {
+        config.enable = false
+        log.warn(`You must set ${description}.The Pinpoint Node JS Agent has been shutdown.`)
+      }
+    })
+
+    if (!ENV_MAP.container() && isContainerEnvironment()) {
+      config.container = true
+    }
+
+    for (const [key, validation] of Object.entries(configurationValueValidations)) {
+      validation()
+    }
+
+    if (typeof this.agentStartupUserDefinedJson['grpc.service_config'] === 'object') {
+      config.grpcServiceConfig = new ServiceConfigBuilder().setJSON(this.agentStartupUserDefinedJson['grpc.service_config']).build()
+    } else {
+      config.grpcServiceConfig = ServiceConfigBuilder.nullObject.build()
+    }
+    return new Config(config)
+  }
+}
+
 module.exports = {
   getConfig,
   clear,
@@ -346,4 +410,5 @@ module.exports = {
   isContainerEnvironment,
   initializeConfig,
   registerLoadedConfig,
+  ConfigBuilder
 }