How to Efficiently Add Policies to Roles in AWS CDK Using TypeScript

Learn how to dynamically attach managed policies to AWS Lambda roles using AWS CDK in TypeScript. This guide will help you streamline your IAM role management process.
---
This video is based on the question https://stackoverflow.com/q/73935559/ asked by the user 'Nelson' ( https://stackoverflow.com/u/17151083/ ) and on the answer https://stackoverflow.com/a/73944912/ provided by the user 'mchlfchr' ( https://stackoverflow.com/u/1654284/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: CDK - Add policies to role with For each

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Streamlining IAM Role Management with AWS CDK

In the fast-paced world of cloud computing, managing AWS resources efficiently can significantly impact your application's performance and security. One common challenge developers face is configuring IAM roles with the right policies for AWS Lambda functions. If you've ever wanted to create Lambda roles dynamically with various attached policies, then this guide is tailored for you. We’ll explore how to efficiently add policies to roles with a focus on using AWS CDK in TypeScript.

The Problem: Dynamic Role Creation

Imagine you have multiple Lambda functions, each requiring different permissions. Instead of manually creating IAM roles and policies for each function, you want to automate this process. Your initial approach might look like this:

[[See Video to Reveal this Text or Code Snippet]]

However, when you try to associate these policies using your role creation logic, you may encounter the following error:

[[See Video to Reveal this Text or Code Snippet]]

This error indicates a fundamental issue: you are trying to pass a string (the policy name) to a method that expects an IManagedPolicy object. Let’s dive into the solution to overcome this hurdle.

The Solution: Correct Role and Policy Attachments

Step 1: Creating Your Lambda Role

Start by defining a method that creates your Lambda role, sets its description, and specifies the services that can assume it. Here’s a snippet of this logic:

[[See Video to Reveal this Text or Code Snippet]]

Here, a new role is created, but we haven't yet added any managed policies.

Step 2: Defining Managed Policies

Next, create instances of your managed policies. Each policy should be defined clearly with the necessary permissions. For example:

[[See Video to Reveal this Text or Code Snippet]]

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Importing Policies and Adding Them

The key to solving the earlier error lies in correctly importing the policies based on their names and adding them to your role:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

ManagedPolicy.fromManagedPolicyName: This method enables you to refer to existing managed policies by their names. This approach ensures that you are passing the correct type required by the addManagedPolicy method.

Adding the Policies: Make sure to reference your imported policy in the addManagedPolicy function, which builds the necessary associations.

Conclusion

By following these steps, you can easily create roles that dynamically attach various policies required by your Lambda functions. This automation not only streamlines the management process but also enhances security by ensuring each function has tailored access.

If you have any further questions or additional use cases, feel free to reach out. Happy coding with AWS CDK and TypeScript!