go-azure-uniquestring

This was created as a bit of fun/curiosity to reverse engineer the uniqueString function used in the Azure ARM template language. The function is used to generate a deterministic hash string based on the inputs provided. This is commonly used to generate unique resource names in Azure.

Usage

To use this project you can follow the below steps:

1. Clone the repository
2. Run the following command to build the project:

go build

1. Then Run the following to execute it:

> go-azure-uniquestring hello world
a7wkljktk6wne

How it works

The uniqueString function takes a number of arguments and does the following:

1. Concatenates all the arguments together with a hyphen separator
2. Uses a seemingly custom implementation of Murmurhash64B to generate a hash of the concatenated string
3. Encodes the resulting hash as a base32 string

So for example the values "hello" and "world" would go through the following steps:

1. Concatenated: "hello-world"
2. Hashed: 571013382255652050
3. Encoded: "a7wkljktk6wne"

Sources

• Azure.Deployments.Expression - Holds a C# reference/implementation to the uniqueString function
• Austin Appleby - The original author of the MurmurHash algorithm