Backend Microservice To Support And Simplify Applications

A simple stateless microservice in Nodejs, with three major functionalities -

• Authentication
• JSON patching
• Image Thumbnail Generation

Setup

The API requires:

• Node.js
• Express
• Mocha - For testing

To get up and running:

1. Clone the repo.

git clone https://github.com/Fidexlee/stateless-microservice.git

2. cd into repo. Use the same directory name(below) if you do not change it.

cd stateless-microservice

3. Setup the application by installing its dependencies with

npm install

4. The app gets up and running on port 3000 with npm start.

5. Important Create a .env file and set jwtSecret to any secret phrase you want.

Testing the API routes.

Since this is mostly an API with post and patch requests, testing will be done with Postman

Authentication

This is a mock authentication so you can pass in any username or password to login.

1. Set the request to POST and the url to /api/users/#.
2. In the Body for the Postman request, select x-www-form-urlencoded.
3. You will be setting 2 keys (for username and password). Set the username key to any name. Set password to any password (minimum of 6 characters).
4. Hit Send. You will get a result in this format:

{
   "user": "moi",
   "authorized": true,
   "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VybmFtZSI6Im1vaSIsImlhdCI6MTUzMjAwNDkwMSwiZXhwIjoxNTMyMDI2NTAxfQ.sonItbpZ_yKsRLDXNfDqwN6yN5VbdMVDhgKAMxDmPFY"
}

JSON patching

Apply json patch to a json object, and return the resulting json object.

1. Set the request to PATCH and the url to /api/patch-object.
2. Set the key jsonObject to an object you would like to patch. Set the key jsonPatchObject to the object you want to use to patch the jsonObject.

Examples:
jsonObject
{ "user": { "firstName": "Albert", "lastName": "Einstein" } }

jsonPatchObject
[{"op": "replace", "path": "/user/firstName", "value": "Leonardo"}, {"op": "replace", "path": "/user/lastName", "value": "da Vinci"}]

3. Since this is a secure route, for testing, you will have to set the token in the Header. Set key as token and value as token you received from Authentication.
4. Expected result should be:

{ "user": { "firstName": "Leonardo", "lastName": "da Vinci" } }

Image Thumbnail Generation

This request contains a public image URL. It downloads the image, resizes to 50x50 pixels, and returns the resulting thumbnail.

1. Set the request to POST and the url to /api/create-thumbnail.
2. Set the key imageUrl to a public image url.
3. Since this is a secure route, for testing, you will have to set the token in the Header. Set key as token and value as token you received from Authentication.
4. Image will be downloaded and converted to a thumbnail of size 50x50 pixels with a sample result as below:

{
   "converted": true,
   "user": "moi",
   "success": "Image has been resized",
   "thumbnail": "./public/images/resized/"
}

Unit Testing

Unit testing is done using Mocha (https://mochajs.org).

Run npm test from the application's root directory.

I used nyc to add coverage to mocha tests by following the Quick Start at (https://istanbul.js.org/)

Adding coverage to your mocha tests could not be easier:

$ npm install --save-dev nyc

Now, simply place the command nyc in front of your existing test command in package.json, for example:

{ "scripts": { "test": "nyc mocha" } }

Logging

All logs are saved in hackerbay.log in the application's root.

Built With

• Node.js
• Express
• Mocha - For testing

Results

1. Test: All tests specified in test.js with Mocha are running well (use: npm test)

2. Istanbul_ coverage is working using nyc at https://istanbul.js.org/ to generate code test coverage reports.