Tag Archives: Lambda

AWS Serveless Computing Example: Wild Rydes Part I

I’ve been working through a tutorial I started in a session I took at AWS re:Invent 2016.  I did not finish the tutorial in class so I started working on it again after getting home from the conference.  The tutorial is on GitHub if you care to follow along.

Admittedly, I’m not the sharpest knife in the drawer(but I am made of the hardest, most persistent steel…they call me, ‘Blue Steel’ – said in my best Ben Stiller voice).  It took me a while to figure out why I could not get the AWS Javascript SDK to allow unauthorized users, vis-a-vis AWS Cognito, to access my DynamoDB Email Table.  Here are some errors and things I learned troubleshooting this:

The latest Firefox browser seems to give better clues about why things are not working in the Developer Console than Google Chrome.  Using Google Chrome, I kept seeing an error like, “Missing Credentials In Config”, and was really confused what exactly that meant.  I was following the tutorial exactly, as far as I could tell, so I could not discern whether this error was from a code change I made or an AWS configuration problem?  Then I looked at my website in Firefox, using the Firefox Developer Console, and could see a little bit better what was going on.

Here’s my main error as seen in the Google Chrome Developer Console:

And here’s the same error as reported by Firefox Developer Console:

Ahh!  So a ‘ResourceNotFoundException’ is being thrown.  Now I could see that my Javascript code probably wasn’t the problem and that my Cognito/IAM Role Configuration might be the culprit.

After further investigation..a day (or so) later…I discovered a simple typo in my DynamoDB Table Name:

The table name should have been ‘Wildrydes_Emails’.  Seriously?!?!  Yes, I’m an idiot (but one made of ‘Blue Steel’…).  Once that was corrected, I was finally able to get my unauthenticated Cognito Role to access my DynamoDB Table.

There is still work to be done in this tutorial, and I’ll blog about any issues I overcome as I encounter them.  My work is being hosted in my AWS account on Cloudfront, so feel free to check it out and submit your email to my DynamoDB database.  Let’s get this startup rolling!