How Do I Debug This Error: 'Duplicate Resource URN'

Introduction

When working with Pulumi, you might encounter the error “Duplicate resource URN.” This error occurs when two or more resources in your Pulumi program are assigned the same Uniform Resource Name (URN). In this guide, we’ll explain how to identify and resolve this common issue.

What’s Actually Happening?

When Pulumi creates and tracks resources, it assigns each one a unique URN. This URN is how Pulumi knows which resource is which in your state file. The “Duplicate resource URN” error happens when you accidentally try to create two resources with the same identity.

This commonly occurs in two scenarios:

1. Name Collision: You’ve created multiple resources of the same type with identical names
2. Loop Issues: You’re creating resources in a loop but not giving each one a unique identifier

Explanation

Step 1: Understand the Error

The “Duplicate resource URN” error occurs when:

1. Multiple resources in your program are created with the same name and type
2. Resources are created in a loop without unique names

Step 2: Identify the Duplicate Resources

1. Check the error message for the specific URN that’s causing the problem
2. Search your code for resources that might share the same name and type
3. Pay special attention to any loops or programmatic resource creation

Step 3: Resolve the Issue

Update the Pulumi program to ensure that each resource has a unique name and type, paying special attention to any loops or programmatic resource creation.

Wrapping Up

The “Duplicate resource URN” error is one of those issues that seems confusing at first but becomes trivial once you understand what’s happening. Remember that Pulumi needs each resource to have its own unique identity, and you’ll be well on your way to smooth deployments.