# CloudFormation 模板代码段
**Topics**
+ [嵌套堆栈](#w2aac11c41c23b5)
+ [等待条件](#w2aac11c41c23b7)
## 嵌套堆栈
### 在模板中嵌套堆栈
此示例模板包含一个称为 `myStack` 的嵌套堆栈资源。在 CloudFormation 通过模板创建堆栈时，它创建 `myStack`，其模板是在 `TemplateURL` 属性中指定的。输出值 `StackRef` 返回 `myStack` 的堆栈 ID，值 `OutputFromNestedStack` 从 `myStack` 资源中返回输出值 `BucketName`。`Outputs.nestedstackoutputname` 是预留格式，用于指定嵌套堆栈的输出值，可以在包含模板的任意位置中使用该格式。
有关更多信息，请参阅 [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-cloudformation-stack.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-cloudformation-stack.html)。
#### JSON
```
1. {
2. "AWSTemplateFormatVersion" : "2010-09-09",
3. "Resources" : {
4. "myStack" : {
5. "Type" : "AWS::CloudFormation::Stack",
6. "Properties" : {
7. "TemplateURL" : "https://s3.amazonaws.com/cloudformation-templates-us-east-1/S3_Bucket.template",
8. "TimeoutInMinutes" : "60"
9. }
10. }
11. },
12. "Outputs": {
13. "StackRef": {"Value": { "Ref" : "myStack"}},
14. "OutputFromNestedStack" : {
15. "Value" : { "Fn::GetAtt" : [ "myStack", "Outputs.BucketName" ] }
16. }
17. }
18. }
```
#### YAML
```
1. AWSTemplateFormatVersion: '2010-09-09'
2. Resources:
3. myStack:
4. Type: AWS::CloudFormation::Stack
5. Properties:
6. TemplateURL: https://s3.amazonaws.com/cloudformation-templates-us-east-1/S3_Bucket.template
7. TimeoutInMinutes: '60'
8. Outputs:
9. StackRef:
10. Value: !Ref myStack
11. OutputFromNestedStack:
12. Value: !GetAtt myStack.Outputs.BucketName
```
### 使用输入参数在模板中嵌套堆栈
此示例模板包含指定输入参数的堆栈资源。CloudFormation 通过该模板创建堆栈时，会将 `Parameters` 属性中声明的值对作为输入参数，供创建 `myStackWithParams` 堆栈的模板使用。在此示例中，已指定 `InstanceType` 和 `KeyName` 参数。
有关更多信息，请参阅 [https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-cloudformation-stack.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-cloudformation-stack.html)。
#### JSON
```
1. {
2. "AWSTemplateFormatVersion" : "2010-09-09",
3. "Resources" : {
4. "myStackWithParams" : {
5. "Type" : "AWS::CloudFormation::Stack",
6. "Properties" : {
7. "TemplateURL" : "https://s3.amazonaws.com/cloudformation-templates-us-east-1/EC2ChooseAMI.template",
8. "Parameters" : {
9. "InstanceType" : "t2.micro",
10. "KeyName" : "mykey"
11. }
12. }
13. }
14. }
15. }
```
#### YAML
```
1. AWSTemplateFormatVersion: '2010-09-09'
2. Resources:
3. myStackWithParams:
4. Type: AWS::CloudFormation::Stack
5. Properties:
6. TemplateURL: https://s3.amazonaws.com/cloudformation-templates-us-east-1/EC2ChooseAMI.template
7. Parameters:
8. InstanceType: t2.micro
9. KeyName: mykey
```
## 等待条件
### 将等待条件用于 Amazon EC2 实例
**重要**
对于 Amazon EC2 和 Auto Scaling 资源，我们建议您使用 CreationPolicy 属性而非等待条件。当实例创建过程成功完成后，将“CreationPolicy”属性添加到这些资源，并使用 cfn-signal 帮助程序脚本发送信号。
如果您无法使用创建策略，请查看以下示例模板，该模板声明了带等待条件的 Amazon EC2 实例。`myWaitCondition` 等待条件使用 `myWaitConditionHandle` 发出信号，使用 `DependsOn` 属性指定等待条件将在创建 Amazon EC2 实例资源后触发，并使用 `Timeout` 属性将等待条件的持续时间指定为 4500 秒。此外，向等待条件发出信号的预签名 URL 将通过 `Ec2Instance` 资源的 `UserData` 属性传输至 Amazon EC2 实例，以使运行在该 Amazon EC2 实例上的应用程序或脚本可以检索预签名 URL，并使用该 URL 向等待条件发出成功或失败信号。您需要使用 `cfn-signal`，或创建向等待条件发出信号的应用程序或脚本。输出值 `ApplicationData` 包含从等待条件信号中传回的数据。
有关更多信息，请参阅 [在 CloudFormation 模板中创建等待条件](using-cfn-waitcondition.md)。
#### JSON
```
1. {
2. "AWSTemplateFormatVersion" : "2010-09-09",
3. "Mappings" : {
4. "RegionMap" : {
5. "us-east-1" : {
6. "AMI" : "ami-0123456789abcdef0"
7. },
8. "us-west-1" : {
9. "AMI" : "ami-0987654321fedcba0"
10. },
11. "eu-west-1" : {
12. "AMI" : "ami-0abcdef123456789a"
13. },
14. "ap-northeast-1" : {
15. "AMI" : "ami-0fedcba987654321b"
16. },
17. "ap-southeast-1" : {
18. "AMI" : "ami-0c1d2e3f4a5b6c7d8"
19. }
20. }
21. },
22. "Resources" : {
23. "Ec2Instance" : {
24. "Type" : "AWS::EC2::Instance",
25. "Properties" : {
26. "UserData" : { "Fn::Base64" : {"Ref" : "myWaitHandle"}},
27. "ImageId" : { "Fn::FindInMap" : [ "RegionMap", { "Ref" : "AWS::Region" }, "AMI" ]}
28. }
29. },
30. "myWaitHandle" : {
31. "Type" : "AWS::CloudFormation::WaitConditionHandle",
32. "Properties" : {
33. }
34. },
35. "myWaitCondition" : {
36. "Type" : "AWS::CloudFormation::WaitCondition",
37. "DependsOn" : "Ec2Instance",
38. "Properties" : {
39. "Handle" : { "Ref" : "myWaitHandle" },
40. "Timeout" : "4500"
41. }
42. }
43. },
44. "Outputs" : {
45. "ApplicationData" : {
46. "Value" : { "Fn::GetAtt" : [ "myWaitCondition", "Data" ]},
47. "Description" : "The data passed back as part of signalling the WaitCondition."
48. }
49. }
50. }
```
#### YAML
```
1. AWSTemplateFormatVersion: '2010-09-09'
2. Mappings:
3. RegionMap:
4. us-east-1:
5. AMI: ami-0123456789abcdef0
6. us-west-1:
7. AMI: ami-0987654321fedcba0
8. eu-west-1:
9. AMI: ami-0abcdef123456789a
10. ap-northeast-1:
11. AMI: ami-0fedcba987654321b
12. ap-southeast-1:
13. AMI: ami-0c1d2e3f4a5b6c7d8
14. Resources:
15. Ec2Instance:
16. Type: AWS::EC2::Instance
17. Properties:
18. UserData:
19. Fn::Base64: !Ref myWaitHandle
20. ImageId:
21. Fn::FindInMap:
22. - RegionMap
23. - Ref: AWS::Region
24. - AMI
25. myWaitHandle:
26. Type: AWS::CloudFormation::WaitConditionHandle
27. Properties: {}
28. myWaitCondition:
29. Type: AWS::CloudFormation::WaitCondition
30. DependsOn: Ec2Instance
31. Properties:
32. Handle: !Ref myWaitHandle
33. Timeout: '4500'
34. Outputs:
35. ApplicationData:
36. Value: !GetAtt myWaitCondition.Data
37. Description: The data passed back as part of signalling the WaitCondition.
```
### 使用 cfn-signal 帮助程序脚本向等待条件发出信号
此示例演示将成功信号发送到等待条件的 `cfn-signal` 命令行。您需要在 EC2 实例的 `UserData` 属性中定义命令行。
#### JSON
```
"UserData": {
"Fn::Base64": {
"Fn::Join": [
"",
[
"#!/bin/bash -xe\n",
"/opt/aws/bin/cfn-signal --exit-code 0 '",
{
"Ref": "myWaitHandle"
},
"'\n"
]
]
}
}
```
#### YAML
```
UserData:
Fn::Base64: !Sub |
#!/bin/bash -xe
/opt/aws/bin/cfn-signal --exit-code 0 '${myWaitHandle}'
```
### 使用 Curl 向等待条件发出信号
此示例显示将成功信号发送到等待条件的 Curl 命令行。
```
1. curl -T /tmp/a "https://cloudformation-waitcondition-test.s3.amazonaws.com/arn%3Aaws%3Acloudformation%3Aus-east-1%3A034017226601%3Astack%2Fstack-gosar-20110427004224-test-stack-with-WaitCondition--VEYW%2Fe498ce60-70a1-11e0-81a7-5081d0136786%2FmyWaitConditionHandle?Expires=1303976584&AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE&Signature=ik1twT6hpS4cgNAw7wyOoRejVoo%3D"
```
其中文件 /tmp/a 包含以下 JSON 结构：
```
1. {
2. "Status" : "SUCCESS",
3. "Reason" : "Configuration Complete",
4. "UniqueId" : "ID1234",
5. "Data" : "Application has completed configuration."
6. }
```
此示例显示发送同一成功信号的 Curl 命令行，将 JSON 发送为命令行参数的情况除外。
```
1. curl -X PUT -H 'Content-Type:' --data-binary '{"Status" : "SUCCESS","Reason" : "Configuration Complete","UniqueId" : "ID1234","Data" : "Application has completed configuration."}' "https://cloudformation-waitcondition-test.s3.amazonaws.com/arn%3Aaws%3Acloudformation%3Aus-east-1%3A034017226601%3Astack%2Fstack-gosar-20110427004224-test-stack-with-WaitCondition--VEYW%2Fe498ce60-70a1-11e0-81a7-5081d0136786%2FmyWaitConditionHandle?Expires=1303976584&AWSAccessKeyId=AKIAIOSFODNN7EXAMPLE&Signature=ik1twT6hpS4cgNAw7wyOoRejVoo%3D"
```