Paranoid Professor

Infrastructure is not only virtual machines or load balancers but also the virtual private cloud that allows everything to communicate with each other. What is also quite convenient is that it can be defined in Terraform and AWS with only a few lines.

I have created a variable vpc_cidr which will hold the CIDR for this VPC. It is defaulted 172.16.0.0/16 which is a tiny network but it can be set to a different value if a larger network is required. This default value is being overridden with 10.10.0.0/16 which is a huge network.

The VPC is defined using two different variables, vpc_cidr and environment. It is rather nifty that you can create more complex values with constants and variables like is being used in the tags definition.

One more important note for the tags is the tag Name is special and is display in all lists as a user friendly name for the AWS element. The output from the terraform apply, just like the plan command will show what changes need to be made but then will make the changes.

For this tutorial we are expecting one item to be created, the first time it is run, and we can see the 1 resource will be added. The last few lines under Outputs shows the values that were setup in the output.tf file.

Creating a VPC really does not show off too much of what you can do with Terraform. However, it is the overarching network that will be filled in and where we can launch our own EC2’s.

This will be demonstrated in the next blog.

Back in the day when you needed a computer or a technical infrastructure you needed some money and you had to go and purchase actual computer equipment. With the wonders of the cloud technology it is possible to connect to one of the cloud vendors and allocate not only a virtual machine but all of the other networking pieces. From load balancers and fire wall rules to network address translation and actual internet access.

None of this is actually news, Amazon has been providing services since 2006. What is new, or relatively new, is the ability to declare how your IT environment should look and have it implemented on command. It is super cool for software development, you can create a test or development environment in the morning and shut it all down before going home.

Of course Amazon has their own tool for this – cloud formation. If you are planning on choosing AWS this might be the best choice. However, if the goal is to not be locked into one cloud vendor perhaps picking your own external tool is a good idea.

There are essentially two different ways to implement the infrastructure.

Declarative

The declarative approach only requires you define what infrastructure you wish to exist at the end. You can run a declarative solution multiple times. The first time the infastructure will be implemented, while the additional runs will verify what you need already exists. If there are no changes, then nothing new will be implemented.

Imperative

The other approach is a set of steps that when run will create their pieces of the infrastructure. These may need to be run in a specific order. Running these steps multiple times may create multiple sets of infrastructure.

My next blog will be about using Terraform

National security is important, you don’t want to let sketchy people into your country. This is somewhat easy to determine for people applying for permanent visas. They have to provide a lot of information and the number of applicants are fairly small, well in comparison to the number of holiday visitors.

I imagine there is a process is a lot harder when the numbers skyrocket. I would think the process would be easier if all the information submitted was accurate. I guess the department of homeland security in the USA doesn’t feel the same way.

Most of the information you need to provide is fairly tame. Essentially the following.

• who are you
• where do you live
• some personal details (passport #)
• what do you do
• where do you work

This information is entered and sometimes the character sets are the same as for the US, but in order to automate the process you would want computers to do all the work. There are at least 31 countries that have diacritics or special characters that are not representable by the Latin character set used by the US.

I know this because if you try and enter a German or French special character the US ESTA site points out that these are illegal names. You are then required to either misspell the name(s) so they are not rejected or the US needs to know all of the substitutions (ie ü = ue)

Either they like making things harder for themselves or perhaps they are not effectively checking out their tourist visitors.

A few years ago I was doing some fooling around with creating my own RESTful services server.

Restful services in Java

Simple server example

Simple client example

Client and Server

360 Degree of restful server

360 Degree of Restful client

Granted these examples were written in Java and Java is a general-purpose, class-based, object-oriented programming language. Java programs can be a bit wordy. These examples were written 2017 and there were easier ways even back then but even since then more and more frameworks have been created to make life easier.

One such solution is using NodeJS and some of the supporting modules. NodeJS is a platform built on top of Chrome’s javascript runtime. NodeJS is both the runtime environment as well as the JavaScript libraries.

It is possible to create a service that you can connect to and transfer data to with only a few lines.

var http = require('http');
http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(3000, "127.0.0.1");
console.log('Server running at http://127.0.0.1:3000/');

This server is super simple. Ok, ok, it is not terribly functional. Perhaps I am getting ahead of myself. First lets install software on your machine.

Installing NodeJS on Linux Mint

Installing NodeJS on a Linux machine, just like most software Linux installations, tends to be just a few lines.

• sudo apt-get install curl software-properties-common
• curl -sL https://deb.nodesource.com/setup_14.x | sudo bash –
• sudo apt-get install nodejs

I chose the long term version 14 instead of the latest release. What you choose would depend on what features you need if you are a bit more flexible (or perhaps less dependent on new features).

Your version can be verified with the following command.

node -v 
> v14.18.2

Beyond the javascript that your programs are developed in it is possible to download additional modules which can be used to encapsulate functionality into little package. This can be done in a few different ways but one of the most common is to use the npm, formerly called Node Package Manager, to download new packages. Installing a single package is done simply by doing an “npm install” followed by the package name.

$ npm install express
npm WARN saveError ENOENT: no such file or directory, open '/home/chris/working/nodejs/simple-server/package.json'
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN enoent ENOENT: no such file or directory, open '/home/chris/working/nodejs/simple-server/package.json'
npm WARN simple-server No description
npm WARN simple-server No repository field.
npm WARN simple-server No README data
npm WARN simple-server No license field.

+ express@4.17.1
added 50 packages from 37 contributors and audited 50 packages in 1.892s
found 0 vulnerabilities

Simple Server

The smallest functional server written in NodeJS would one that listens to a specific endpoint for any of the common HTTP messages (GET,PUT,POST,DELETE). This example program will listen to port 8181 on the server.

var express = require('express');
var app = express();

app.get('/', function (req, res) {
   res.send('Hello World');
})

var server = app.listen(8081, function () {
   let port = server.address().port
   
   console.log(`Example app listening on port ${port} `)
})

This can be tested by running the server on your local machine attaching to it from your web browser.

Running the server is super easy as well, simply run the NodeJS (node) with the name of the script to run.

> node server.js 
Server running at http://127.0.0.1:3000/

Looking at the code you would expect to see your classic Hello World to show up when your visit this endpoint.

It is important to install any modules that you will use. There is quite a bit of existing functionality but the express module needs to be installed before it can be used.

NodeJS has actually encapsulated all of the hard work. A simple server that will wait for HTTP GET statements.

This simple server program has a lot of functionality. It is an example of three different endpoints that can be called. The /hello and /goodbye are pretty obvious and simply return a json message to the caller.

const express = require('express')
let app = express()
app.use(express.json());



app.get('/hello', (request, response) => {
  response.json({ "message": "hello world" });
});

app.get('/goodbye', (request, response) => {
  response.status(200).send("goodbye world");
});

app.get('/x/:id', (request, response) => {
  response.status(200).send(request.params.id );
});

const port = process.env.PORT || 3000;
app.listen(port, () => console.log(`listing on port ${port}` ));

The third endpoint is a bit more interesting as it allows you to pass in a parameter and easily as part of the URL. This particular example might be good for retrieving a value (ie book) by the code that is passed in. Because this is a service and not a web server it is only returning a value and not a webpage. But this is pretty useful as a backend server for your website.

Just as important as the ability to get information it is important to be able to pass in a complex structure.

app.post('/newitem', (request, response) => {

  let body = request.body;
  console.log("body of post")
  console.log(body);


  var keys = Object.keys(body);
  for (i in keys)
    console.log(i,keys[i],body[keys[i]]);

  response.status(200).send(request.params.id );
});

This example post endpoint allows us to pass in any structure and print it out to the console.

In my next post I will expand on this for other features that might be useful.