# Amazon Aurora 的自定义端点的 AWS CLI 示例
<a name="Aurora.Endpoint.Tutorial"></a>

以下教程使用带 Unix Shell 语法的 AWS CLI 示例，来说明您如何可以定义一个具有多个“小型”数据库实例和几个“大型”数据库实例的集群，并创建自定义端点来连接到每组数据库实例。要在您自己的系统上运行类似的命令，您应该充分熟悉使用 Aurora 集群和 AWS CLI 的基础知识，以便为区域、子网组和 VPC 安全组等参数提供您自己的值。

此示例演示初始设置步骤：创建一个 Aurora 集群并向其添加数据库实例。这是一个异构集群，意味着并非所有数据库实例都具有相同的容量。大多数实例使用 AWS 实例类 `db.r4.4xlarge`，但最后两个数据库实例使用 `db.r4.16xlarge`。这些示例 `create-db-instance` 命令中的每个命令都将其输出打印到屏幕，并将 JSON 的副本保存在文件中以供以后检查。

```
aws rds create-db-cluster --db-cluster-identifier custom-endpoint-demo --engine aurora-mysql \
     --engine-version 8.0.mysql_aurora.3.04.0 --master-username $MASTER_USER --manage-master-user-password \
     --db-subnet-group-name $SUBNET_GROUP  --vpc-security-group-ids $VPC_SECURITY_GROUP \
     --region $REGION

for i in 01 02 03 04 05 06 07 08
do
  aws rds create-db-instance --db-instance-identifier custom-endpoint-demo-${i} \
     --engine aurora --db-cluster-identifier custom-endpoint-demo --db-instance-class db.r4.4xlarge \
     --region $REGION \
     | tee custom-endpoint-demo-${i}.json
done

for i in 09 10
do
  aws rds create-db-instance --db-instance-identifier custom-endpoint-demo-${i} \
     --engine aurora --db-cluster-identifier custom-endpoint-demo --db-instance-class db.r4.16xlarge \
     --region $REGION \
     | tee custom-endpoint-demo-${i}.json
done
```

较大的实例将保留以用于特殊类型的报告查询。为了使它们不太可能被提升为主实例，以下示例将其提升层更改为最低优先级。此示例指定了生成主用户密码并在 Secrets Manager 中对其进行管理的 `--manage-master-user-password` 选项。有关更多信息，请参阅 [使用 Amazon Aurora 和 AWS Secrets Manager 管理密码](rds-secrets-manager.md)。或者，您可以使用 `--master-password` 选项自行指定和管理密码。

```
for i in 09 10
do
  aws rds modify-db-instance --db-instance-identifier custom-endpoint-demo-${i} \
    --region $REGION --promotion-tier 15
done
```

假设您只想为资源最密集的查询使用两个“较大”实例。为此，您可以首先创建一个自定义的只读终端节点。然后，您可以添加静态成员列表，以便该终端节点仅连接到这些数据库实例。这些实例已处于最低的提升层，因此它们都不太可能被提升到主实例。如果其中一个被提升到主实例，它将无法通过该终端节点访问，因为我们指定了 `READER` 类型，而不是 `ANY` 类型。

以下示例演示了创建和修改终端节点命令，并演示了示例 JSON 输出，其中显示了自定义终端节点的初始状态和已修改状态。

```
$ aws rds create-db-cluster-endpoint --region $REGION \
    --db-cluster-identifier custom-endpoint-demo \
    --db-cluster-endpoint-identifier big-instances --endpoint-type reader
{
    "EndpointType": "CUSTOM",
    "Endpoint": "big-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com",
    "DBClusterEndpointIdentifier": "big-instances",
    "DBClusterIdentifier": "custom-endpoint-demo",
    "StaticMembers": [],
    "DBClusterEndpointResourceIdentifier": "cluster-endpoint-W7PE3TLLFNSHXQKFU6J6NV5FHU",
    "ExcludedMembers": [],
    "CustomEndpointType": "READER",
    "Status": "creating",
    "DBClusterEndpointArn": "arn:aws:rds:ca-central-1:111122223333:cluster-endpoint:big-instances"
}

$ aws rds modify-db-cluster-endpoint --db-cluster-endpoint-identifier big-instances \
    --static-members custom-endpoint-demo-09 custom-endpoint-demo-10 --region $REGION
{
    "EndpointType": "CUSTOM",
    "ExcludedMembers": [],
    "DBClusterEndpointIdentifier": "big-instances",
    "DBClusterEndpointResourceIdentifier": "cluster-endpoint-W7PE3TLLFNSHXQKFU6J6NV5FHU",
    "CustomEndpointType": "READER",
    "DBClusterEndpointArn": "arn:aws:rds:ca-central-1:111122223333:cluster-endpoint:big-instances",
    "StaticMembers": [
        "custom-endpoint-demo-10",
        "custom-endpoint-demo-09"
    ],
    "Status": "modifying",
    "Endpoint": "big-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com",
    "DBClusterIdentifier": "custom-endpoint-demo"
}
```

集群的默认 `READER` 终端节点可以连接到“小型”或“大型”数据库实例，这使得在集群繁忙时预测查询性能和可扩展性变得不切实际。为了在数据库实例集之间清晰地划分工作负载，您可以忽略默认的 `READER` 终端节点，并创建第二个自定义终端节点，该终端节点连接到所有其他数据库实例。以下示例通过创建自定义终端节点，然后添加排除列表来实现这一点。稍后添加到集群的任何其他数据库实例将自动添加到此终端节点。`ANY` 类型表示此终端节点总共与 8 个实例相关联：主实例和另外 7 个 Aurora 副本。如果示例使用的是 `READER` 类型，则自定义终端节点仅与 7 个 Aurora 副本相关联。

```
$ aws rds create-db-cluster-endpoint --region $REGION --db-cluster-identifier custom-endpoint-demo \
    --db-cluster-endpoint-identifier small-instances --endpoint-type any
{
    "Status": "creating",
    "DBClusterEndpointIdentifier": "small-instances",
    "CustomEndpointType": "ANY",
    "EndpointType": "CUSTOM",
    "Endpoint": "small-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com",
    "StaticMembers": [],
    "ExcludedMembers": [],
    "DBClusterIdentifier": "custom-endpoint-demo",
    "DBClusterEndpointArn": "arn:aws:rds:ca-central-1:111122223333:cluster-endpoint:small-instances",
    "DBClusterEndpointResourceIdentifier": "cluster-endpoint-6RDDXQOC3AKKZT2PRD7ST37BMY"
}

$ aws rds modify-db-cluster-endpoint --db-cluster-endpoint-identifier small-instances \
    --excluded-members custom-endpoint-demo-09 custom-endpoint-demo-10 --region $REGION
{
    "DBClusterEndpointIdentifier": "small-instances",
    "DBClusterEndpointArn": "arn:aws:rds:ca-central-1:c7tj4example:cluster-endpoint:small-instances",
    "DBClusterEndpointResourceIdentifier": "cluster-endpoint-6RDDXQOC3AKKZT2PRD7ST37BMY",
    "CustomEndpointType": "ANY",
    "Endpoint": "small-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com",
    "EndpointType": "CUSTOM",
    "ExcludedMembers": [
        "custom-endpoint-demo-09",
        "custom-endpoint-demo-10"
    ],
    "StaticMembers": [],
    "DBClusterIdentifier": "custom-endpoint-demo",
    "Status": "modifying"
}
```

以下示例检查此集群的终端节点的状态。集群仍具有其原始集群终端节点（`EndPointType` 为 `WRITER`），您仍将它用于管理、ETL 和其他写入操作。它仍具有其原始 `READER` 终端节点，您不会使用此终端节点，因为它的每个连接都可能被定向到“小型”或“大型”数据库实例。自定义终端节点使得此行为是可预测的，连接保证使用基于您指定的终端节点的“小型”或“大型”数据库实例之一。

```
$ aws rds describe-db-cluster-endpoints --region $REGION
{
    "DBClusterEndpoints": [
        {
            "EndpointType": "WRITER",
            "Endpoint": "custom-endpoint-demo.cluster-c7tj4example.ca-central-1.rds.amazonaws.com",
            "Status": "available",
            "DBClusterIdentifier": "custom-endpoint-demo"
        },
        {
            "EndpointType": "READER",
            "Endpoint": "custom-endpoint-demo.cluster-ro-c7tj4example.ca-central-1.rds.amazonaws.com",
            "Status": "available",
            "DBClusterIdentifier": "custom-endpoint-demo"
        },
        {
            "Endpoint": "small-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com",
            "CustomEndpointType": "ANY",
            "DBClusterEndpointArn": "arn:aws:rds:ca-central-1:111122223333:cluster-endpoint:small-instances",
            "ExcludedMembers": [
                "custom-endpoint-demo-09",
                "custom-endpoint-demo-10"
            ],
            "DBClusterEndpointResourceIdentifier": "cluster-endpoint-6RDDXQOC3AKKZT2PRD7ST37BMY",
            "DBClusterIdentifier": "custom-endpoint-demo",
            "StaticMembers": [],
            "EndpointType": "CUSTOM",
            "DBClusterEndpointIdentifier": "small-instances",
            "Status": "modifying"
        },
        {
            "Endpoint": "big-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com",
            "CustomEndpointType": "READER",
            "DBClusterEndpointArn": "arn:aws:rds:ca-central-1:111122223333:cluster-endpoint:big-instances",
            "ExcludedMembers": [],
            "DBClusterEndpointResourceIdentifier": "cluster-endpoint-W7PE3TLLFNSHXQKFU6J6NV5FHU",
            "DBClusterIdentifier": "custom-endpoint-demo",
            "StaticMembers": [
                "custom-endpoint-demo-10",
                "custom-endpoint-demo-09"
            ],
            "EndpointType": "CUSTOM",
            "DBClusterEndpointIdentifier": "big-instances",
            "Status": "available"
        }
    ]
}
```

最后的示例演示了与自定义终端节点的连续数据库连接如何连接到 Aurora 集群中的各种数据库实例。`small-instances` 终端节点始终连接到 `db.r4.4xlarge` 数据库实例，这些实例是此集群中编号较低的主机。

```
$ mysql -h small-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com -u $MYUSER -p
mysql> select @@aurora_server_id;
+-------------------------+
| @@aurora_server_id      |
+-------------------------+
| custom-endpoint-demo-02 |
+-------------------------+

$ mysql -h small-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com -u $MYUSER -p
mysql> select @@aurora_server_id;
+-------------------------+
| @@aurora_server_id      |
+-------------------------+
| custom-endpoint-demo-07 |
+-------------------------+

$ mysql -h small-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com -u $MYUSER -p
mysql> select @@aurora_server_id;
+-------------------------+
| @@aurora_server_id      |
+-------------------------+
| custom-endpoint-demo-01 |
+-------------------------+
```

`big-instances` 终端节点始终连接到 `db.r4.16xlarge` 数据库实例，这些实例是此集群中编号最高的两个主机。

```
$ mysql -h big-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com -u $MYUSER -p
mysql> select @@aurora_server_id;
+-------------------------+
| @@aurora_server_id      |
+-------------------------+
| custom-endpoint-demo-10 |
+-------------------------+

$ mysql -h big-instances.cluster-custom-c7tj4example.ca-central-1.rds.amazonaws.com -u $MYUSER -p
mysql> select @@aurora_server_id;
+-------------------------+
| @@aurora_server_id      |
+-------------------------+
| custom-endpoint-demo-09 |
+-------------------------+
```