Serverless URL Shortener

This project provides an easy-to-set-up serverless URL shortener that can be run for little-to-no cost.

Serverless

"Does serverless mean something beyond a good buzzword?"

Yes. Thanks to what AWS provides, serverless means that:

• If you have the AWS CLI set up (and AWS Serverless dotnet tool installed), deployment is ridiculously easy
  • This includes every single thing that the app requires
  • You can essentially set up a single config file, run a command, and have the whole app working
• It will cost about $0.01 a month to run with a medium-low trafficked site
  • Only S3 will cost something, since it has a minimum of 1 cent when hosting things
    • This only applies if you leave the deployment artefacts in S3 (these can be removed after deployment)
  • Both Lambda and DynamoDB (the only main dependencies of the app) have permanent free tiers

Setup

To deploy this app, follow these steps:

AWS CLI

Ensure you have the AWS CLI set up and working properly. You can test your config with aws sts get-caller-identity.

AWS Lambda dotnet Tool

You will need to have the AWS Lambda tool installed (and by extension, the .NET Core 2.1 sdk), which can be done by dotnet tool install -g Amazon.Lambda.Tools.

Config

You will need to define a config file at scripts/.env.local. This will contain all of the config you need to deploy the app. It looks something like this:

SERVERLESS_NAME=MyUrlShortener
S3_BUCKET=my-url-shortener-build
AUTH_KEY=secure-auth-key
CURRENT_ORIGIN=https://myshortener.com

• SERVERLESS_NAME
  • This is the name of the app used by AWS CloudFormation
  • In order to ensure that you don't redeploy the app multiple times, set this once and never change it
• S3_BUCKET
  • This is the bucket the build result is set to for use by CloudFormation when deploying
  • It has to exist already, but the default config works fine
• AUTH_KEY
  • This is the authentication key that will be used to log into the admin console
  • To make this secure, make it a long & complex enough
  • If you think someone has gained access to it, you will have to edit the lambda directly and change the key
    • CloudFormation doesn't yet support updating environment variables
  • If empty, then the admin console won't let anyone sign in at all
    • You can use this behaviour to disable logging in completely
• CURRENT_ORIGIN
  • This is the origin to use when displaying the short URLs in the admin console
  • Purely a graphical option, doesn't change behaviour

Deployment

If you have set up all the other parts correctly, you can just call scripts/build.sh deploy and CloudFormation will deploy the app to AWS, along with all its dependencies.

Custom URL

You can set up a custom URL like normal in the AWS API Gateway console.