Скачать или смотреть How to Attach IAM Policy to Lambda Function for SNS Publish Access

Learn how to properly configure IAM policies to enable your AWS Lambda function to publish messages to SNS. This guide outlines the necessary steps and considerations to avoid common errors.
---
This video is based on the question https://stackoverflow.com/q/74634527/ asked by the user 'Stretch0' ( https://stackoverflow.com/u/3528590/ ) and on the answer https://stackoverflow.com/a/74634577/ provided by the user 'Marcin' ( https://stackoverflow.com/u/248823/ ) 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: How to attach iam policy to Lambda function for SNS publish access?

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.
---
How to Attach IAM Policy to Lambda Function for SNS Publish Access

When working with AWS services, it's not uncommon to encounter the need for specific permissions. One such requirement is allowing your AWS Lambda function to publish messages to Amazon SNS (Simple Notification Service). Many users in the AWS community have faced similar challenges, especially when using Infrastructure as Code (IaC) tools like Terraform.

In this guide, we'll explore how to correctly attach an IAM policy to your Lambda function to grant it the necessary SNS publish access.

The Problem: IAM Policy Configuration

You may find yourself in a situation where you’ve created a Lambda function in Terraform and want to allow it to publish messages to an SNS topic. You might set up an IAM role and assume that this role correctly defines permissions for your Lambda function. However, when running terraform apply, you may encounter an error similar to:

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

This error often arises due to incorrect configurations in your IAM policies. Let's walk through the solution to ensure your Lambda function has the right permissions.

Understanding IAM Policies and Role Assumptions

The Role of Assume Role Policy

An assume role policy is crucial because it specifies who or what can assume the IAM role. In the case of AWS Lambda, only the Lambda service should be able to assume the role. However, the actual permissions that the role grants are defined in a separate policy.

Correctly Setting Up IAM Role for Lambda

Here’s how to configure the IAM role correctly in your Terraform setup:

Define the IAM Role: Make sure your assume role policy only indicates that the Lambda service can assume this role.

Define Inline Policy: Use an inline policy attached to the IAM role to grant the necessary permissions (e.g., sns:Publish).

Sample Terraform Configuration

Here’s an example of how to set up the IAM role correctly in Terraform:

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

Defining the IAM Policy Document

Make sure your IAM policy document permits the necessary actions. Here’s how to structure your SNS publish permission policy document:

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

Final Steps

Once you’ve updated your Terraform configuration with the correct IAM role definition and the inline policy, proceed with the following steps:

Run terraform plan to ensure there are no issues before applying changes.

Use terraform apply to implement the changes.

Conclusion

By carefully setting up your IAM role and defining the permissions correctly, you can successfully enable your AWS Lambda function to publish messages to SNS. Pay close attention to the structure of your assume role policy versus your permissions policy, and make use of inline policies when necessary.

Following these guidelines will help you avoid common pitfalls and ensure your Lambda function has the access it needs to operate correctly.

If you encounter any further issues or have questions, don’t hesitate to reach out to the AWS community or consult the official AWS documentation!