# 将策略附加到 DynamoDB 现有表
您可以使用 DynamoDB 控制台、[PutResourcePolicy](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_PutResourcePolicy.html) API、AWS CLI、AWS SDK 或 [CloudFormation 模板](rbac-create-table.md#rbac-create-table-cfn)将基于资源的策略附加到现有表或修改现有策略。
## 附加新策略的 AWS CLI 示例
以下 IAM 策略示例使用 `put-resource-policy` AWS CLI 命令将基于资源的策略附加到现有表。此示例允许用户 {{John}} 对名为 {{MusicCollection}} 的现有表执行 [GetItem](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html)、[PutItem](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_PutItem.html)、[UpdateItem](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html) 和 [UpdateTable](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateTable.html) API 操作。
切记用特定资源信息替换{{斜体}}文本。
```
aws dynamodb put-resource-policy \
--resource-arn arn:aws:dynamodb:us-west-2:{{123456789012}}:table/{{MusicCollection}} \
--policy \
"{
\"Version\": \"2012-10-17\",
\"Statement\": [
{
\"Effect\": \"Allow\",
\"Principal\": {
\"AWS\": \"arn:aws:iam::{{111122223333}}:user/{{John}}\"
},
\"Action\": [
\"dynamodb:GetItem\",
\"dynamodb:PutItem\",
\"dynamodb:UpdateItem\",
\"dynamodb:UpdateTable\"
],
\"Resource\": \"arn:aws:dynamodb:us-west-2:{{123456789012}}:table/{{MusicCollection}}\"
}
]
}"
```
## 有条件地更新现有策略的 AWS CLI 示例
要有条件地更新表现有的基于资源的策略，可以使用可选 `expected-revision-id` 参数。以下示例仅当策略存在于 DynamoDB 中且其当前修订版 ID 与提供的 `expected-revision-id` 参数相匹配时，才会更新该策略。
```
aws dynamodb put-resource-policy \
--resource-arn arn:aws:dynamodb:us-west-2:123456789012:table/{{MusicCollection}} \
--expected-revision-id 1709841168699 \
--policy \
"{
\"Version\": \"2012-10-17\",
\"Statement\": [
{
\"Effect\": \"Allow\",
\"Principal\": {
\"AWS\": \"arn:aws:iam::111122223333:user/{{John}}\"
},
\"Action\": [
\"dynamodb:GetItem\",
\"dynamodb:UpdateItem\",
\"dynamodb:UpdateTable\"
],
\"Resource\": \"arn:aws:dynamodb:us-west-2:123456789012:table/{{MusicCollection}}\"
}
]
}"
```
## AWS 管理控制台
1. 登录 AWS 管理控制台，并打开 DynamoDB 控制台：[https://console.aws.amazon.com/dynamodb/](https://console.aws.amazon.com/dynamodb/)。
1. 在控制面板中，选择现有表。
1. 导航到**权限**选项卡，然后选择**创建表策略**。
1. 在基于资源的策略编辑器中，添加要附加的策略，然后选择**创建策略**。
以下 IAM 策略示例允许用户 {{John}} 对名为 {{MusicCollection}} 的现有表执行 [GetItem](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html)、[PutItem](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_PutItem.html)、[UpdateItem](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html) 和 [UpdateTable](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateTable.html) API 操作。
切记用特定资源信息替换{{斜体}}文本。
------
#### [ JSON ]
****
```
{
"Version":"2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"AWS": "arn:aws:iam::{{111122223333}}:user/{{username}}"
},
"Action": [
"dynamodb:GetItem",
"dynamodb:PutItem",
"dynamodb:UpdateItem",
"dynamodb:UpdateTable"
],
"Resource": "arn:aws:dynamodb:{{us-east-1}}:{{123456789012}}:table/{{MusicCollection}}"
}
]
}
```
------
## AWS SDK for Java 2.x
以下 IAM 策略示例使用 `putResourcePolicy` 方法将基于资源的策略附加到现有表。此策略允许用户对现有表执行 [GetItem](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html) API 操作。
```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.PutResourcePolicyRequest;
/**
* Before running this Java V2 code example, set up your development
* environment, including your credentials.
*
* For more information, see the following documentation topic:
*
* [Get started with the AWS SDK for Java 2.x](https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/get-started.html)
*/
public class PutResourcePolicy {
public static void main(String[] args) {
final String usage = """
Usage:
Where:
tableArn - The Amazon DynamoDB table ARN to attach the policy to. For example, arn:aws:dynamodb:us-west-2:{{123456789012}}:table/{{MusicCollection}}.
allowedAWSPrincipal - Allowed AWS principal ARN that the example policy will give access to. For example, arn:aws:iam::{{123456789012}}:user/{{John}}.
""";
if (args.length != 2) {
System.out.println(usage);
System.exit(1);
}
String tableArn = args[0];
String allowedAWSPrincipal = args[1];
System.out.println("Attaching a resource-based policy to the Amazon DynamoDB table with ARN " +
tableArn);
Region region = Region.US_WEST_2;
DynamoDbClient ddb = DynamoDbClient.builder()
.region(region)
.build();
String result = putResourcePolicy(ddb, tableArn, allowedAWSPrincipal);
System.out.println("Revision ID for the attached policy is " + result);
ddb.close();
}
public static String putResourcePolicy(DynamoDbClient ddb, String tableArn, String allowedAWSPrincipal) {
String policy = generatePolicy(tableArn, allowedAWSPrincipal);
PutResourcePolicyRequest request = PutResourcePolicyRequest.builder()
.policy(policy)
.resourceArn(tableArn)
.build();
try {
return ddb.putResourcePolicy(request).revisionId();
} catch (DynamoDbException e) {
System.err.println(e.getMessage());
System.exit(1);
}
return "";
}
private static String generatePolicy(String tableArn, String allowedAWSPrincipal) {
return "{\n" +
" \"Version\": \"2012-10-17\",\n" +,
" \"Statement\": [\n" +
" {\n" +
" \"Effect\": \"Allow\",\n" +
" \"Principal\": {\"AWS\":\"" + allowedAWSPrincipal + "\"},\n" +
" \"Action\": [\n" +
" \"dynamodb:GetItem\"\n" +
" ],\n" +
" \"Resource\": \"" + tableArn + "\"\n" +
" }\n" +
" ]\n" +
"}";
}
}
```