node: add knex example to sample

nodejs/sqlcommenter-nodejs/samples/express-opentelemetry/README.md

@@ -7,7 +7,8 @@ OpenTelemetry trace and span ID to the queries for correlation.
 
 ## Running
 
-This example reads some environment variables to connect to a Cloud SQL database.
+The examples read some environment variables to connect to a Cloud SQL
+database.
 
 - `DBHOST` - The hostname, ip, or path to unix socket directory for Cloud SQL
 database. For example, if you are using Cloud SQL proxy with a unix socket,
@@ -24,13 +25,22 @@ $ export DBPASSWORD="<database password>"
 $ export DBDIALECT="<postgres | mysql>"
 $ npm install
 
-# on first run, create some data
+# before the first run, create some data
 $ npm run createTodos
+```
 
-# run the sequelize server
+To run the sequelize server example:
+```bash
 $ npm run sequelizeServer
+```
 
-# in a separate terminal
+Or run the knex server:
+```bash
+$ npm run knexServer
+```
+
+In a separate terminal, hit the server with `curl` and check the output:
+```bash
 $ curl http://localhost:8000
 {"todos":[{"id":11,"title":"Do dishes","description":null,"done":false,"createdAt":"2020-11-06T01:59:50.111Z","updatedAt":"2020-11-06T01:59:50.111Z"},{"id":12,"title":"Buy groceries","description":null,"done":false,"createdAt":"2020-11-06T01:59:50.111Z","updatedAt":"2020-11-06T01:59:50.111Z"},{"id":13,"title":"Do laundry","description":"Finish before Thursday!","done":false,"createdAt":"2020-11-06T01:59:50.111Z","updatedAt":"2020-11-06T01:59:50.111Z"},{"id":14,"title":"Clean room","description":null,"done":false,"createdAt":"2020-11-06T01:59:50.111Z","updatedAt":"2020-11-06T01:59:50.111Z"},{"id":15,"title":"Wash car","description":null,"done":false,"createdAt":"2020-11-06T01:59:50.112Z","updatedAt":"2020-11-06T01:59:50.112Z"}]}
 

nodejs/sqlcommenter-nodejs/samples/express-opentelemetry/knexConnection.js

@@ -0,0 +1,30 @@
+const { wrapMainKnexAsMiddleware } = require("@google-cloud/sqlcommenter-knex");
+const Knex = require("knex");
+
+const sqlcommenterMiddleware = wrapMainKnexAsMiddleware(
+  Knex,
+  {
+    traceparent: true,
+    tracestate: true,
+
+    // These are optional and will cause a high cardinality burst traced queries
+    db_driver: false,
+    route: false,
+  },
+  { TraceProvider: "OpenTelemetry" }
+);
+
+const knex = Knex({
+  client: "pg",
+  connection: {
+    host: process.env.DBHOST,
+    user: process.env.DBUSERNAME,
+    password: process.env.DBPASSWORD,
+    database: "postgres",
+  },
+});
+
+module.exports = {
+  knex,
+  sqlcommenterMiddleware,
+};

nodejs/sqlcommenter-nodejs/samples/express-opentelemetry/knexServer.js

@@ -0,0 +1,62 @@
+const { LogLevel } = require("@opentelemetry/core");
+const { NodeTracerProvider } = require("@opentelemetry/node");
+const { BatchSpanProcessor } = require("@opentelemetry/tracing");
+const {
+  TraceExporter,
+} = require("@google-cloud/opentelemetry-cloud-trace-exporter");
+const { logger, sleep } = require("./util");
+
+const tracerProvider = new NodeTracerProvider({
+  logLevel: LogLevel.DEBUG,
+  logger,
+});
+tracerProvider.addSpanProcessor(
+  new BatchSpanProcessor(new TraceExporter({ logger }), {
+    bufferSize: 500,
+    bufferTimeout: 5 * 1000,
+  })
+);
+tracerProvider.register();
+
+// OpenTelemetry initialization should happen before importing any libraries
+// that it instruments
+const express = require("express");
+const app = express();
+const { sqlcommenterMiddleware, knex } = require("./knexConnection");
+
+const tracer = tracerProvider.getTracer(__filename);
+
+async function main() {
+  if (!(await knex.schema.hasTable("Todos"))) {
+    console.error("Todos table does not exist. Run `npm run createTodos`");
+    process.exit(1);
+  }
+
+  const PORT = 8000;
+
+  // SQLCommenter express middleware injects the route into the traces
+  app.use(sqlcommenterMiddleware);
+
+  app.get("/", async (req, res) => {
+    const span = tracer.startSpan("sleep for no reason (parent)");
+    await sleep(250);
+    span.end();
+
+    const getRecordsSpan = tracer.startSpan("query records with knex");
+    await tracer.withSpan(getRecordsSpan, async () => {
+      tracer.startSpan("testing 123").end();
+      const todos = await knex.select().table("Todos").limit(20);
+      const countByDone = await knex
+        .select("done", knex.raw("COUNT(id) as count"))
+        .table("Todos")
+        .groupBy("done");
+      res.json({ countByDone, todos });
+    });
+    getRecordsSpan.end();
+  });
+  app.listen(PORT, async () => {
+    console.log(`⚡️[server]: Server is running at https://localhost:${PORT}`);
+  });
+}
+
+main().catch(console.error);