# GetBucketPolicy

GetBucketPolicy returns the policy document attached to a bucket. On STRG buckets do not
carry policies, so there is never a document to return: the operation checks that the bucket
exists and answers `404 NoSuchBucketPolicy` - the same answer Amazon S3 gives for a bucket that
has never had a policy. Tools that read the policy while describing a bucket already treat
`NoSuchBucketPolicy` as "no policy", so they work unchanged.

Who can reach a bucket is decided by the permissions and bucket scope of each
[access key](https://docs.strg.com/access-keys), together with the bucket's *Bucket Protection* setting in the
dashboard. That keeps everything about access in two places you can see at a glance, rather than
in a JSON document.

**Info: Good to know on STRG**

- Buckets have no policies, so the answer is always `404 NoSuchBucketPolicy`, never a policy
  document.
- PutBucketPolicy, DeleteBucketPolicy and GetBucketPolicyStatus are answered with
  `501 NotImplemented`, so a client knows straight away.
- `x-amz-expected-bucket-owner` is welcome and has nothing to check: a key only ever reaches
  buckets of its own account.

## When you'd use it

- **Tools that describe a bucket.** Infrastructure-as-code tools, backup utilities and inventory
  scripts written for Amazon S3 read a bucket's policy along with its other settings. On
  STRG they get the familiar "no policy" answer and carry on describing the bucket.
- **Security and compliance checks.** A script that audits buckets for policies granting public
  access finds none here. Whether a bucket is readable without credentials is its *Bucket
  Protection* setting, which [Anonymous reads](https://docs.strg.com/s3-api/overview#anonymous-reads) describes.

## Request

```http
GET /?policy HTTP/1.1
Host: my-bucket.s3.eu-central-1.strg.com
Authorization: AWS4-HMAC-SHA256 Credential=...
x-amz-date: 20260926T120000Z
x-amz-content-sha256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
```

The path-style form is `GET /my-bucket?policy` on `s3.eu-central-1.strg.com` -
[Addressing](https://docs.strg.com/s3-api/overview#addressing) explains both.

### Permissions

The access key needs **Read bucket settings** (`buckets:read-config`). Every access key holds
it, whether it covers all buckets or only some - a key scoped to specific buckets reads only
those. [Access keys](https://docs.strg.com/access-keys) has the details.

### URI parameters

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `Bucket` | String | Yes | The bucket whose policy to read. |
| `policy` | Flag | Yes | Selects this operation. Sent with no value. |

Any other query parameter is answered with `501 NotImplemented`, so a client knows straight away
that it has no effect here.

### Request headers

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `x-amz-expected-bucket-owner` | String | No | Welcome, with nothing to check: an access key only ever reaches its own account's buckets. |

### Request body

None.

## Response

For a bucket that exists, the answer is always the `404 NoSuchBucketPolicy` error below. A
`200 OK` with a policy document is never sent.

### Response headers

| Name | Description |
| --- | --- |
| `Content-Type` | `application/xml` - the error document. |
| `x-amz-request-id` | The request ID, handy for a support request. |

### Response body

| Element | Type | Description |
| --- | --- | --- |
| `Policy` | String (JSON) | Never sent. On Amazon S3, a successful answer's body is the bucket policy as a JSON document. |

This is what STRG sends instead, for a path-style request - `Resource` is the request path:

```xml
<?xml version="1.0" encoding="UTF-8"?>
<Error>
  <Code>NoSuchBucketPolicy</Code>
  <Message>The bucket policy does not exist</Message>
  <Resource>/my-bucket</Resource>
  <BucketName>my-bucket</BucketName>
  <RequestId>...</RequestId>
</Error>
```

## Errors

These are the errors this request can return, and the situation behind each one.

| Code | HTTP status | When |
| --- | --- | --- |
| `NoSuchBucketPolicy` | 404 | Always, for a bucket that exists and that the access key can reach. |
| `NoSuchBucket` | 404 | The bucket does not exist, belongs to another account, is in a region other than the endpoint's, or the account stores nothing in the endpoint's region yet. |
| `AccessDenied` | 403 | The access key is scoped to buckets that do not include this one, the account is not active, or the request is unsigned. |
| `InvalidAccessKeyId` | 403 | The access key does not exist, has expired or been revoked - or it was created moments ago and is not usable yet in a region where the account already stores data, in which case the same request works shortly afterwards. |
| `SignatureDoesNotMatch` | 403 | The request signature does not match. |
| `RequestTimeTooSkewed` | 403 | The request time is more than 15 minutes from the server's. |
| `AuthorizationHeaderMalformed` | 400 | The signature's credential scope names a region other than the endpoint's. |
| `NotImplemented` | 501 | The request carries a query parameter this operation does not accept. |
| `SlowDown` | 503 | Too many requests. The `Retry-After` header says when a retry is welcome; the AWS SDKs retry on their own. |
| `ServiceUnavailable` | 503 | A temporary failure; the same request can be retried. |
| `InternalError` | 500 | An unexpected failure while checking the bucket; the same request can be retried. |

## Differences from Amazon S3

The table lists each place where STRG behaves differently, and what that means for a client.

| Aspect | Amazon S3 | STRG |
| --- | --- | --- |
| Bucket policies | A JSON policy document per bucket | Buckets have no policies. The answer is always `404 NoSuchBucketPolicy` |
| Controlling access | Bucket policies, IAM and ACLs | Access key permissions and bucket scope, plus *Bucket Protection* in the dashboard. [Access keys](https://docs.strg.com/access-keys) has the details |
| Setting or removing a policy | PutBucketPolicy, DeleteBucketPolicy | Answered with `501 NotImplemented` |
| Bucket in another region | `301` redirect with `x-amz-bucket-region` | `404 NoSuchBucket`. A bucket is reached through its own regional endpoint. |
| `x-amz-expected-bucket-owner` | Checked against the bucket owner | Welcome, with nothing to check |

## Examples

Every client reports `NoSuchBucketPolicy` as an error, and each example below treats it as
"this bucket has no policy".

**AWS CLI**

```bash
aws s3api get-bucket-policy \
  --bucket my-bucket \
  --endpoint-url https://s3.eu-central-1.strg.com \
  --region eu-central-1
```

The command ends with `An error occurred (NoSuchBucketPolicy) when calling the GetBucketPolicy
operation: The bucket policy does not exist` and a non-zero exit status.

**Python (boto3)**

```python
import boto3
from botocore.exceptions import ClientError

s3 = boto3.client(
    "s3",
    endpoint_url="https://s3.eu-central-1.strg.com",
    region_name="eu-central-1",
)

try:
    response = s3.get_bucket_policy(Bucket="my-bucket")
    print(response["Policy"])
except ClientError as error:
    if error.response["Error"]["Code"] == "NoSuchBucketPolicy":
        print("no bucket policy")
    else:
        raise
```

**JavaScript (AWS SDK v3)**

```javascript
import { GetBucketPolicyCommand, S3Client } from "@aws-sdk/client-s3";

const client = new S3Client({
  endpoint: "https://s3.eu-central-1.strg.com",
  region: "eu-central-1",
});

try {
  const response = await client.send(new GetBucketPolicyCommand({ Bucket: "my-bucket" }));
  console.log(response.Policy);
} catch (error) {
  if (error.name === "NoSuchBucketPolicy") {
    console.log("no bucket policy");
  } else {
    throw error;
  }
}
```

## Related

- [GetBucketAcl](https://docs.strg.com/s3-api/GetBucketAcl)
- [PutBucketAcl](https://docs.strg.com/s3-api/PutBucketAcl)
- [GetPublicAccessBlock](https://docs.strg.com/s3-api/GetPublicAccessBlock)
- [Access keys](https://docs.strg.com/access-keys)
- [S3 API overview](https://docs.strg.com/s3-api/overview#supported-operations) - including the [other S3 operations](https://docs.strg.com/s3-api/overview#other-s3-operations)