CDK Unique Value Resource

This module provides a CloudFormation resource type that produces guaranteed-unique values. You may !GetAtt to fetch and use the unique values in your templates. We created this project to help manage dynamic ECS services behind a shared Application Load Balancer.

This project provides AWS CDK Constructs to increase ease of use in your CDK projects. You may install a shared version of the resource provider in a region by using the included CDK app. Or, you may embed and use the provider in your app without any sharing.

Features:

• Create groups of unique values
• Generate unique integers in a given range
• Generate UUID1 and UUID4 values
• Generate unique word combinations (think rustic-albatross or amazed-wallabies)

Getting Started

To install a shared version of the resource provider, install and bootstrap AWS CDK, then type the following command:

cdk --app 'npx @wheatstalk/cdk-unique-value-resource' deploy UniqueValueResource

Once this stack has deployed, you may add the dependency to your CDK app:

# Install with yarn
yarn add @wheatstalk/cdk-unique-value-resource
# Install with npm
npm install @wheatstalk/cdk-unique-value-resource

After which, you may start to use it immediately:

import {
  UniqueValueProvider,
  UniqueIntegerResource,
} from '@wheatstalk/cdk-unique-value-resource';

// Use the shared resource provider.
const provider = UniqueValueProvider.fromRegionalStack(this, 'UniqueValueProvider');

// Create a unique value
const uniqueInteger = new UniqueIntegerResource(this, 'UniqueInteger', {
  provider,
  // Guaranteed uniqueness in the group named 'testing'. You may use a fixed
  // string value as like shown. You may also reference another resource,
  // such as a load balancer listener rule's arn.
  group: 'testing',
  // Start at 10000, inclusive
  start: 10000,
  // Stop at 40000, exclusive
  stop: 40000,
  // Allocate unique numbers
  step: 1,
});

// Display the unique value
new CfnOutput(this, 'UniqueIntegerValue', {
  value: uniqueInteger.uniqueValue,
});

To remove the shared version of the resource provider, type the following:

cdk --app 'npx @wheatstalk/cdk-unique-value-resource' destroy UniqueValueResource

Note: By design, CloudFormation will prevent the deletion of the resource provider stack unless you remove all references to the provider's custom resource type.

Architecture Notes

• CDK-based project
• Lambda-backed custom resource provider
• Lambda code written in Python
• Allocated values are tracked in a DynamoDB table

Development Notice

This project is still in development. We do not recommend using it in production until it is stable version 1.0.0. We do not have any estimates on when this may be.

Contributing

We're open to feedback on this project.