Traces	Metrics	App Logs	Custom Logs	Profiling
✅	✖️	✖️	✅	✖️

This guide walks you through setting up Application Performance Monitoring (APM) on a Deno application. These instructions can also be found on the Installation page in your Middleware Account. View example code here.

Prerequisites

MW Host Agent

Middleware Host Agent (MW Agent). To install the MW Agent, see our installation guide.

Deno Version

Deno version 1.41.2 or above. Check your Deno version with the following command:

Shell

deno --version

Install

Step 1: Import dependencies

Import necessary packages into your Deno project from the Deno standard library and middlewareio library:

TypeScript

import { serve } from "https://deno.land/[email protected]/http/server.ts";
import { track, httpTracer, info, warn, error, debug } from "https://deno.land/x/[email protected]/mod.ts";

Step 2: Configure Tracing

Trace network requests with the following track() function:

TypeScript

track({
serviceName: '{SERVICE_NAME}',
target: 'https://{ACCOUNT-UID}.middleware.io:443',
accessToken: '{ACCOUNT_KEY}',
})

Step 3: Define Request Handler

Define how your server responds to incoming HTTP requests with the following function:

TypeScript

function handler(_req: Request): Response {
   const data = {
       message: `Hello world!`,
   };
   return new Response(JSON.stringify(data), { headers: { 'Content-Type': 'application/json' } });
}

Step 4: Start Your Server

Start an HTTP server with the serve function:

TypeScript

await serve(httpTracer(handler));

Step 5: Logging [Optional]

Add additional logging information with the following functions:

TypeScript

info("info");
warn("warn");
error("error");
debug("debug");

Hono Framework

To use Middleware with the Hono framework, follow the example below:

TypeScript

import { Hono } from "https://deno.land/x/[email protected]/mod.ts";
import {
  debug,
  error,
  httpTracer,
  info,
  track,
  warn,
} from "https://deno.land/x/[email protected]/mod.ts";

// Initialize the Middleware tracker with the name of your service, your account URL, and API key
track({
  serviceName: "hono-service",
  target: "https://<ACCOUNT_URL>:443",
  accessToken: "<MIDDLEWARE_API_KEY>",
});

const app = new Hono();

const rootHandler = (c) => {
  const infoMessage = "Hello Hono!";
  // Log an info message
  info(infoMessage);
  return c.text(`${infoMessage}\n`);
};

const greetHandler = (c) => {
  const name = c.req.param("name");
  if (name.length < 2) {
    const warnMessage = "A name cannot be a single letter";
    // Log a warning message
    warn(warnMessage);
    return c.text(`${warnMessage}\n`);
  }

  const debugMessage = `Hello ${name}`;
  // Log a debug message
  debug(debugMessage);
  return c.text(`${debugMessage}\n`);
};

const errorHandler = (c) => {
  const errorMessage = "An error occurred";
  // Log an error message
  error(errorMessage);
  throw new Error();
};

app.get("/", rootHandler);
app.get("/greet/:name", greetHandler);
app.get("/error", errorHandler);

const server = Deno.serve(
  {
    port: 8000,
    onListen({ port, hostname }) {
      console.log(`Server started at ${`http://${hostname}:${port}`}`);
    },
  },
  // Wrap the app.fetch method with the httpTracer to begin instrumenting
  httpTracer(app.fetch),
);

Need assistance or want to learn more about Middleware? Contact us at support[at]middleware.io.

​Prerequisites

​Install

​Step 1: Import dependencies

​Step 2: Configure Tracing

​Step 3: Define Request Handler

​Step 4: Start Your Server

​Step 5: Logging [Optional]

​Hono Framework

Prerequisites

Install

Step 1: Import dependencies

Step 2: Configure Tracing

Step 3: Define Request Handler

Step 4: Start Your Server

Step 5: Logging [Optional]

Hono Framework