ssmirr / Caches

Infrastructure Components

In this workshop, we'll cover the basics of adding infrastructure components to a web application, meow.io. In particular, we will focus on using redis to construct basic infrastructure components, such as a cache and queue, and intergrating them into a web application.

Part 1. Setup and Overview ⬅️
Part 2. Using express and redis
Part 3. Using caches and queues in meow.io

Setup

Before you get started

Import this as a notebook or clone this repo locally. Also, ensure you install latest version of docable!

docable-server import https://github.com/CSC-DevOps/Caches

Create a new virtual machine that will be configured with redis and node.js:

bakerx run

Note: Run bakerx ssh meow.io to connect to the virtual machine.

A simple in-memory data store

You will be using redis server and node-redis client to build some simple infrastructure components:

const redis = require('redis');
const client = redis.createClient(6379, '127.0.0.1');

In general, you can run all the redis commands in the following manner: client.CMD(args). For example:

client.set("key", "value");
client.get("key", function(err,value){ console.log(value)});

🎯 Try it out!

const redis = require("redis");

// Prepare client connection
let client = redis.createClient(6379, '192.168.44.81', { connect_timeout: 5000 });

// Set and retrieve a key
client.set( "hello", "redis", (err, res) => {

  console.log(`Set: "hello" => ${res}`);

  client.get("hello", (err, res) => {
    console.log( `Get: "hello" => "${res}"`);
    
    // Terminate client connection (otherwise we'd hang)
    client.end(true);
  })
});

A simple web server

In this workshop we use express to make a simple web server:

let server = app.listen(3003, function () {

  const host = server.address().address;
  const port = server.address().port;

  console.log(`Example app listening at http://${host}:${port}`);
})

Express uses the concept of routes to use pattern matching against requests and sending them to specific functions. You can simply write back a response body:

app.get('/', function(req, res) {
	res.send('hello world')
})

🎯 Try it out!

From our host machine, change into cd basics, and then npm install. We will then start the server with node index.js.

🌏 Visit the web server on http://localhost:3003/ in another tab or click the Reload button to load the server:

Reload

<iframe id="serviceFrameSend" src="http://localhost:3003/" width="800" height="200" frameborder="1"></iframe>

When you are done, use Control+C to stop the server.

Next

We will get more hands on practice with express and redis in, Part 2. Using express and redis.