Enforcing object prefix permission constraints for a MinIO IAM user

Question

Pulumi · Accepted Answer

MinIO is a High Performance Object Storage that is API compatible with Amazon S3 cloud storage service. To enforce object prefix permission constraints for a MinIO IAM user, we will use IAM policies that allow us to define these permissions.

The IAM policies can be attached to a user, defining what actions are allowed or denied for which S3 buckets and prefixes. The `aws.iam.User` resource allows us to create a new IAM user in AWS, and the `aws.iam.Policy` and `aws.iam.UserPolicyAttachment` resources enable us to create an IAM policy and attach it to a user, respectively.

Let's understand the Pulumi program that enforces object prefix permission constraints for a MinIO IAM user. We'll go through it step by step:

1. Define an IAM policy with permissions constraints on a specific object prefix.
2. Create an IAM user.
3. Attach the IAM policy to the user.

Below is the TypeScript program that performs these steps.

```typescript
import * as aws from "@pulumi/aws";

const userName = "minio-user";

// Create the IAM user
const minioUser = new aws.iam.User(userName, {
    name: userName,
});

// Define the IAM policy with object prefix permissions.
const bucketName = "your-bucket-name"; // The name of the S3 bucket
const objectPrefix = "user-prefix/"; // The prefix for which the user will have permissions

const minioPolicyDocument = aws.iam.getPolicyDocument({
    statements: [{
        actions: [
            "s3:GetObject",
            "s3:PutObject",
            "s3:ListBucket",
        ],
        resources: [
            `arn:aws:s3:::${bucketName}/${objectPrefix}*`, // The resources within the bucket with the specified prefix
        ],
    }],
});

const minioPolicy = new aws.iam.Policy("minioPolicy", {
    name: "minioPolicy",
    policy: minioPolicyDocument.json, // Attach the IAM policy document as JSON.
});

// Attach the IAM policy to the user
const minioUserPolicyAttachment = new aws.iam.UserPolicyAttachment("minioUserPolicyAttachment", {
    user: minioUser.name,
    policyArn: minioPolicy.arn, // The Amazon Resource Name (ARN) of the policy.
});

// Export the necessary attributes
export const minioUserName = minioUser.name;
export const minioUserArn = minioUser.arn;
```

This program accomplishes the following:

- It creates a new IAM user called `minio-user` which we could use in the context of MinIO or any AWS-S3 compatible service that supports IAM-style authentication and authorization.
- It generates an IAM policy document that includes permission statements for actions like `GetObject`, `PutObject`, and `ListBucket`. These permissions are restricted to resources with a specified prefix in the bucket `your-bucket-name`. You must replace `your-bucket-name` with the actual bucket name and `user-prefix/` with the actual prefix you want to restrict the user to.
- Next, it creates an IAM policy resource named `minioPolicy` with the defined policy document.
- The policy is then attached to the user via the `UserPolicyAttachment` resource, which binds the permissions defined in the policy to the user created.

At the end, the program exports the IAM user's name and ARN, which can be used to further interact with or reference the IAM user in other parts of your infrastructure as code or the AWS console.

You will need to replace the placeholders in the `bucketName` and `objectPrefix` variables to reflect your actual S3 bucket name and the object prefix you are securing access to. Also, ensure that your AWS provider is configured correctly to allow Pulumi to interact with your AWS account.

If you plan to use this with MinIO specifically, please ensure your MinIO installation is set up to integrate with AWS IAM policies, and adjust the resource ARNs if necessary, as they can differ from AWS S3 depending on your MinIO configuration.