AWS Grant Access After Files are in the Bucket

Introduction

Amazon Web Services (AWS) provides a secure and scalable cloud computing platform for businesses of all sizes. One of its most popular services is Amazon S3, which is a highly durable and infinitely scalable object storage service that allows you to store and retrieve files in the cloud. However, by default, the files stored in an S3 bucket are not publicly accessible.

In this tutorial, we will show you how to grant access to files in an S3 bucket after they are uploaded. We will use AWS Identity and Access Management (IAM) policies to define the permissions that are granted to specific users or roles.

Prerequisites

Before we begin, you will need the following:

• An AWS account
• An S3 bucket
• A user or role in IAM with permission to upload files

Steps

Step 1: Create IAM Policy

To grant access to files in an S3 bucket, you need to define an IAM policy that grants permissions to specific users or roles. Here's how you can create a new policy:

1. Open the IAM console in your AWS account.
2. Click on "Policies" in the left navigation bar.
3. Click on "Create policy" button.
4. Under "Create your own policy", select "JSON" tab.
5. Copy and paste the following code into the policy editor:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AllowListObjects",
            "Effect": "Allow",
            "Action": [
                "s3:ListBucket",
                "s3:GetObject",
                "s3:GetObjectAcl"
            ],
            "Resource": [
                "arn:aws:s3:::YOUR_BUCKET_NAME",
                "arn:aws:s3:::YOUR_BUCKET_NAME/*"
            ]
        }
    ]
}

6. Replace "YOUR_BUCKET_NAME" with the name of your S3 bucket.
7. Click on "Review policy" button.
8. Enter a name and description for the policy.
9. Click on "Create policy" button.

Step 2: Attach policy to user or role

After creating the IAM policy, you need to attach it to the user or role that needs access to the S3 bucket. Here's how you can do it:

1. Open the IAM console in your AWS account.
2. Click on "Users" or "Roles" in the left navigation bar, depending on whether you want to grant access to a user or role.
3. Select the user or role to which you want to attach the policy.
4. Click on "Add permissions" or "Attach policies" button.
5. Search for the name of the policy you just created.
6. Select the policy from the search results.
7. Click on "Add permissions" or "Attach policy" button.

Step 3: Test access to S3 bucket

After completing the above steps, you can now test if the user or role has access to the S3 bucket. Here's how you can test it:

1. Open the AWS S3 console in your AWS account.
2. Select the S3 bucket that you want to grant access to.
3. Upload a file to the S3 bucket.
4. Right-click on the file, and select "Make public".
5. Note the URL of the file.
6. Log out of your AWS account.
7. Open a new browser tab and paste the URL of the file into the address bar.
8. If you can access the file, then the policy is working correctly.

Conclusion

In this tutorial, we showed you how to grant access to files in an S3 bucket after they are uploaded. By using IAM policies, you can define the permissions that are granted to specific users or roles. This allows you to control access to your files in a granular way, ensuring that your data is secure and your users have the access they need.