At Instacart, we run our infrastructure on AWS, so our systems often deal with AWS ARNs. We often run into cluttered code, and needed to develop a solution for simpler, safer code. That’s why today, we’re releasing arn, a Python library that simplifies parsing, validating, and working with AWS ARNs in a type-safe way.

Here’s an example of what arncan do, in this case parsing a Target Group ARN:

arn also checks that its input is indeed a valid ARN:

If you’re using type annotations, arn can help you enforce that function parameters are valid ARNs:

If you have multiple resources in your AWS infrastructure that have some attributes in common, arn can also be used to generate an ARN from another:

What resources are supported?

arn is still quite new, so it only supports the AWS resource types that we use here at Instacart, plus a few more popular ones:

• Capacity provider
• Container Instance
• Cluster
• Service
• Task definition
• TaskSet

ELBv2

• Load Balancers (Application and Network)
• ALB/NLB Listeners
• ALB/NLB Listener Rules
• Target Group

• STS Assumed role

• Access point
• Bucket
• Object

How do I get it?

arn supports Python 3.6 and up and has no runtime dependencies (except for a dataclasses backport if you’re on Python 3.6). To install it, simply run:

pip install arn

or add arn to your setup.pyor requirements.txt.

The docs are available at https://arn.readthedocs.io/en/latest/

I want to contribute

If you’re interested in contributing, or just want to take a look at the source, come visit us at https://github.com/instacart/arn.