Building an API Gateway and uploading files to S3 via Postman

2024-08-15 3 min read Projects Barny Baron

Journey: 📊 Community Builder 📊

Subject matter: Building on AWS

Task: Building an API Gateway and uploading files to S3 via Postman!

Using the 6 Pillars of the AWS Well-Architected Framework, Reliability will be achieved in this build.

This week, I built an API Gateway and uploaded files to an S3 bucket via the Postman platform.

Gateway

In the scenario where you have a front-end application but want to keep your back-end S3 bucket private, you can use an API Gateway in the middle to post files to S3.

For this project, I am using Postman to call my API with PUT requests.

I have chosen not to use a Cognito Authoriser in this instance, however it would be best practice to do so.

Uploading

Resource credit: This IaC architecture was created using guidance from Helio Tarnowski on Medium Here.

What did I use to build this environment?

AWS Management Console
Postman API Platform
IAM and JSON
CORS

What is built?

An S3 bucket
An API Gateway [REST API]

In this task, I created an S3 bucket and then created an IAM Role with permissions to allow API Gateway to push objects into S3.

I then created a REST API Gateway and configured it manually with a PUT Method and S3 as my AWS Service.

The HTTP method was configured as a PUT.

I used path overrides of bucket/filename so that I could replace my bucket name and object name placeholders when I came to use Postman.

After setting my URL path parameters, I was able to Deploy my API.

Before testing, I permitted media types to be allowed in the PUT request. To keep this simple, I used / to allow all files.

All I needed to do now was load up the Postman platform and test.

I obtained my Invoke URL from the Stages area in my API, replaced the {bucket} placeholder with my bucket name, and replaced {filename} with one of my stock photos. In this instance, it was called ‘binary.jpg’.

I added my photo to the Body of the Postman PUT request and clicked Send.

200 response showed in Postman citing a successful PUT.

I navigated back to my S3 bucket, refreshed it and there was my binary.jpg file uploaded from Postman, via my API Gateway.

To improve security on this in the future, I could add a Cognito Authoriser and use an access token in my Postman header!