chore: refactor span attribute assignments into util

plugins/node/opentelemetry-plugin-koa/src/koa.ts

@@ -17,13 +17,14 @@
 import { BasePlugin } from '@opentelemetry/core';
 import * as koa from 'koa';
 import * as shimmer from 'shimmer';
-import { Parameters, KoaMiddleware, KoaContext, AttributeNames } from './types';
+import { Parameters, KoaMiddleware, KoaContext, KoaComponentName } from './types';
 import { VERSION } from './version';
+import { getMiddlewareMetadata } from './utils';
 
 
 /** Koa instrumentation plugin for OpenTelemetry */
 export class KoaPlugin extends BasePlugin<typeof koa> {
-  static readonly component = 'koa';
+  static readonly component = KoaComponentName;
 
     constructor(readonly moduleName: string) {
         super('@opentelemetry/plugin-koa', VERSION);
@@ -75,24 +76,20 @@ export class KoaPlugin extends BasePlugin<typeof koa> {
   }
 
   private _patchLayer (middlewareLayer: KoaMiddleware) {
+    const plugin = this;
     const patchedLayer = (context: KoaContext, next: koa.Next) => {
         const currentSpan = this._tracer.getCurrentSpan();
         if (!currentSpan) {
             console.log('--- No current span');
         } 
 
-        var mwSpan = this._tracer.startSpan('middleware');
+        const metadata = getMiddlewareMetadata(context);
+        const span = plugin._tracer.startSpan(metadata.name, {
+          attributes: metadata.attributes,
+        });
 
-        mwSpan.setAttribute(AttributeNames.COMPONENT, KoaPlugin.component);
-        mwSpan.setAttribute(AttributeNames.PATH, context.path);
-        mwSpan.setAttribute(AttributeNames.PROTOCOL, context.protocol);
-        mwSpan.setAttribute(AttributeNames.STATUS, context.status);
-        mwSpan.setAttribute(AttributeNames.HOST, context.host);
-        mwSpan.setAttribute(AttributeNames.METHOD, context.method);
-        mwSpan.setAttribute(AttributeNames.KOA_TYPE, 'middleware');
-
         var result = middlewareLayer(context, next);
-        mwSpan.end();
+        span.end();
         return result;
 
     }

plugins/node/opentelemetry-plugin-koa/src/types.ts

@@ -31,5 +31,7 @@ export enum AttributeNames {
     METHOD = 'http.method',
     KOA_TYPE = 'koa.type',
     KOA_NAME = 'koa.name'
-}
+};
+
+export const KoaComponentName : string = 'koa';
 

plugins/node/opentelemetry-plugin-koa/src/utils.ts

@@ -0,0 +1,38 @@
+/*!
+ * Copyright 2020, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import { AttributeNames, KoaContext, KoaComponentName } from './types';
+import { Attributes } from '@opentelemetry/api';
+
+
+export const getMiddlewareMetadata = (
+    context: KoaContext
+) : {
+    attributes: Attributes;
+    name: string;
+} => {
+        return { 
+            attributes: {
+                [AttributeNames.PATH]: context.path,
+                [AttributeNames.PROTOCOL]: context.protocol,
+                [AttributeNames.STATUS]: context.status,
+                [AttributeNames.HOST]: context.host,
+                [AttributeNames.METHOD]: context.method,
+                [AttributeNames.KOA_TYPE]: 'middleware',
+                [AttributeNames.COMPONENT]: KoaComponentName
+        },
+        name: 'middleware'
+    }
+}