👀 Views: 100 💬 Answers: 1 📅 Created: 2025-06-10

aws lambda s3 permissions iam JavaScript

I've searched everywhere and can't find a clear answer. I'm working with a `403 Forbidden` behavior when my AWS Lambda function attempts to access an S3 bucket. The Lambda function is supposed to read objects from the bucket, but it fails with the behavior message: `Access Denied: User: arn:aws:sts::123456789012:assumed-role/MyLambdaRole/... is not authorized to perform: s3:GetObject on resource: arn:aws:s3:::my-bucket-name/*`. My Lambda function is running in the `us-east-1` region and has an IAM role attached that I configured with a custom policy. Here's the policy I attached to the Lambda execution role: ```json { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": "s3:GetObject", "Resource": "arn:aws:s3:::my-bucket-name/*" } ] } ``` I've also ensured that the S3 bucket has a bucket policy that allows access from the Lambda role: ```json { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Principal": { "AWS": "arn:aws:iam::123456789012:role/MyLambdaRole" }, "Action": "s3:GetObject", "Resource": "arn:aws:s3:::my-bucket-name/*" } ] } ``` I have double-checked the bucket name and IAM role ARN, and they're correct. Furthermore, I am running this Lambda function with a test event that provides the object key correctly, using `my-file.txt` which exists in the S3 bucket. Despite all these configurations, I'm still getting the permission denied behavior. I've tried redeploying the Lambda function and clearing the cache, but nothing seems to resolve the scenario. Is there something I'm missing or a specific condition I need to consider when setting permissions for Lambda to access S3? This is part of a larger API I'm building. Am I missing something obvious?