Harrison Ifeanyi

Posted on Apr 19

Build an End-to-End AWS Web Application

Building The Power of Math using the following AWS Services:

AWS Amplify
AWS Lambda
Amazon API Gateway
Amazon DynamoDB
AWS Identity and Access Management

Requirements:

Create/host the webpage
Invoke math functionality
A way to do some math
Store/return the math result
Handle permissions

TASK 1:
A way to create/host the webpage

AWS Amplify: It is used to build and host websites

Created a text document (preferably notepad) named INDEX but saved it as “.html”
Opened the INDEX.HTML file via Notepad and pasted the POWER OF MATH code in it

Once that's done, zip the file

Now, it's time to use AWS Amplify to deploy it

Log into your AWS Management Console and navigated to the AWS Amplify function

Under the AWS Amplify Header, click on the GET STARTED button
Under HOST A WEB APP, click on GET STARTED which takes you to the page below:

Select DEPLOY WITHOUT GIT PROVIDER
Clicked on CONTINUE
On the MANUAL DEPLOY page, under APP-NAME, I called mine PowerOfMath
Under ENVIRONMENT NAME, I typed in DEV
Drag the zipped file and import it into AWS Amplify
Click on SAVE and DEPLOY Button

It was successfully deployed below:

Copy the DOMAIN link and open it in a tab
View the page

TASK 2:
A way to do some math

This is a perfect use case for LAMBDA FUNCTION. This is a piece of code that runs serverless upon some trigger

On the AWS Console, navigate to LAMBDA
Click on CREATE A FUNCTION

Under CREATE FUNCTION, select AUTHOR FROM SCRATCH
Under BASIC INFORMATION;

A. Function Name: I went with PowerOfMathFunction

B. Runtime: I selected PYTHON 3.9

Click on the CREATE FUNCTION button

Once it has been created, scroll down the page and paste the PYTHON code written for this function.

Type CTRL + S to save the code
Clicked the DEPLOY button

Click on the dropdown icon beside the TEST button
Click on CONFIGURE TEST EVENT

On the modal that pops up, choose the CREATE NEW EVENT, I chose to name the event PowerOfMathTestEvent.
Leave the event-sharing settings on private.

On the EVENT JSON section of the modal page, I edited the content made available to the following;

{
“base”: 2,
“exponent”: 8
}

Now, scroll down and clicked the SAVE button

Now, click on the DEPLOY button first and the TEST button after

It gave the following result:
"statusCode": 200,
"body": "\"Your result is 256.0\""

This shows that the LAMBDA FUNCTION is working

TASK 3:
A way to invoke the math functionality

API Gateway - used to build HTTP, REST & WebSocket APIs
Navigate to the AWS API Gateway section of the console
Out of the options displayed, click on the BUILD button under the REST API

On the Create REST API page:

Select NEW API
API Name: PowerOfMathAPI
I left the API Endpoint Type at REGIONAL

Click on the CREATE API button

On the left side of the screen, ensure that RESOURCES was selected
Click on the CREATE METHOD button

On the CREATE METHOD page;

Under Method type, select POST
Under Integration type, choose LAMBDA FUNCTION
Under Lambda function section, I selected the LAMBDA FUNCTION I HAD CREATED FOR THIS PROJECT

Now clicked on CREATE METHOD

At this moment, there is a need to activate Cross-Origin Resources Sharing (CORS)

To get that done, click on the “/” icon between CREATE RESOURCES and POST. The CORS button was on the right.
On the ENABLE CORS page;

Under Access-Control-Allow-Methods section, tick the POST option and clicked on the SAVE button

At this point, click on the DEPLOY API button

Stage: NEW STAGE
Stage Name: Dev
Then click on the DEPLOY button

I copied the INVOKE URL and kept it in my notepad for later

To Test if the API is Working:

Click on RESOURCES
Select POST
Select TEST

I typed in the same equation that was used earlier and the result?
Right below:

TASK 4:
A. Somewhere to store/return the math result
B. Set Permission on the execution role for Lambda

DynamoDB - A Key Value, NoSQL Database
IAM: Identity and Access Management

Navigate to Dynamo DB and clicked on CREATE TABLE
For Table name, I chose PowerOfMathDatabase
For Partition key, I typed ID
Click on CREATE TABLE button

Click on the PowerOfMathDatabase
In the GENERAL INFORMATION section under OVERVIEW, copy the Amazon Resource Name (ARN) and save on your notepad

At this point, it was important to ensure that the LAMBDA FUNCTION would be able to write into Dynamo DB

So navigate back to the LAMBDA page and click on the CONFIGURATION section

Click on the URL under ROLE NAME and it opens the IAM page below:

On this IAM page, click on ADD PERMISSION and chose the CREATE INLINE POLICY
Click on JSON and paste the EXECUTION ROLE POLICY code

Add the DYNAMO DB ARN link that was copied earlier to the RESOURCE part of the code
Click on the NEXT button
For Policy name, I chose PowerOfMath and clicked on CREATE POLICY
Policy Created!

Now, there is a need to update the LAMBDA FUNCTION that writes to the database

Navigate back to LAMBDA and clicked on CODE
Under the PowerOfMathFunction Folder, view the PYTHON code you had saved earlier (lambda_function.py)
I replaced it with the PowerOfMath - LAMBDA FUNCTION FINAL code and pressed CTRL + S to save
Click on DEPLOY. After it had deployed, clicked on TEST.

TASK 5:
Implement a connector by linking AWS Amplify with AWS API Gateway

I updated the code on the INDEX.HTML file
I also inputted the API Gateway URL I had copied earlier

Save the updated file and re-zipped it
Navigate back to AWS Amplify
Click on the CHOOSE FILE button, selected the updated INDEX.HTML file and uploaded it