Skip to content

The Problem with "It Works on My Computer"


Disclaimer: This is an opinionated post based off of my own experience. Your experience and opinions may differ and that is okay. I welcome your respectful and engaged conversation. Most of my cloud experience is with Amazon Web Services, so this post will be AWS heavy. A lot of this applicable to other cloud providers though.

Scenario #1: Working on a serverless first team

We hire a new person that’s new to serverless. Regardless of how long they’ve been a professional software developer, the first question is often some variation of:

“How do I run this locally on my computer?”

There are many tools out there that can emulate AWS on your computer, but I’ve experienced some issues with this approach.

Scenario #2: Working on a non-serverless first team

Some companies use more traditional infrastructure such as EC2 instances and RDS. Running a local version of a Node.js server against a local Postgres database is great for fast, iterative development and works well most of the time.

Where this falls apart is when integrating another AWS service such as S3. I’ve seen software developers who do not have much cloud experience, but are great at writing code do the following:

  1. Authenticate with AWS using administrative access credentials locally on their computer.
  2. Run a server locally on their computer which uploads a file to an S3 bucket located in a non-prod AWS account.
  3. It works!
  4. They submit their code and it gets merged into the main branch.
  5. The code gets deployed to a non-prod environment (staging or something similar).
  6. They test uploading to the S3 bucket and it fails on the non-prod environment.
  7. ”I don’t know what’s going on because it worked locally for me!” 🤔

Clouds Image

Photo by Sander Sammy on Unsplash

  1. Someone more experienced with IAM recognizes that the permissions on the cloud and the local environment differ.
  2. The more experienced person fixes the permissions issues in the cloud. 🚀

Unsolicited advice


I’ve seen these scenarios play out on many different teams at different companies. The reason is due to developers needing to change their mindset.

Today it is very common for software applications to use cloud services. We as developers should also evolve our development environments to match the new paradigm.

Let’s build better software together. Good luck out there. 💪🏻