[英]How to obtain pseudo-parameters user data with AWS CDK?
I would like to convert this working CloudFormation Code into a proper Python AWS CDK version.我想将此工作 CloudFormation 代码转换为合适的 Python AWS CDK 版本。 The EC2 shall be launched within a VPC. EC2 应在 VPC 内启动。 The user data are used to install apps.用户数据用于安装应用程序。 After completion, I need a call back to Cloudformation.完成后,我需要回调 Cloudformation。
UserData:
Fn::Base64: !Sub |
<script>
cfn-signal.exe --exit-code 0 --stack ${AWS::StackId} --resource EC2Instance --region ${AWS::Region}
</script>
I tried to use the direct way with aws_cdk.core.Fn.base64
which is not working with regard to pseudo-parameters declaration within the EC2 the user data.我尝试对aws_cdk.core.Fn.base64
使用直接方式,该方式aws_cdk.core.Fn.base64
用于 EC2 用户数据中的伪参数声明。
This is my current state:这是我目前的状态:
EC2InstanceUserData = aws_ec2.UserData.for_windows()
EC2InstanceUserData.add_commands(
"cfn-signal.exe --exit-code 0 ",
"--stack ",
VpcStack.stack_id(XXX, e.g. self?), # not working
" --resource ",
VpcStack.get_logical_id(XXX, e.g. self?), # not working
" --region ",
VpcStack.region(XXX, e.g. self?) # not working
)
Pros:优点:
core.Aws
object such as Region or Account ID.可以接受任意数量的变量,例如上下文中定义的变量,而不仅仅是core.Aws
对象中的变量,例如区域或账户 ID。Cons:缺点:
user_data.sh
script with $!{
rather than just ${
.您将需要使用$!{
而不仅仅是${
为user_data.sh
脚本中的所有常规变量的引用添加前缀。Use a mappings dict and parse it into the Fn.sub function.使用映射字典并将其解析为Fn.sub函数。 Personally I like these declared at the top of my user_data.sh
script rather than substituted throughout so use a double underscore as a prefix and as a suffix.我个人喜欢在我的user_data.sh
脚本顶部声明的这些,而不是整个替换,因此使用双下划线作为前缀和后缀。 Note that you still need to consider the mappings as variables rather than strings.请注意,您仍然需要将映射视为变量而不是字符串。
ie IE
$cat user_data.sh
ACCOUNT_ID="${__ACCOUNT_ID__}"
REGION="${__REGION__}"
## Updates
yum update -y
## Fix time
ln -sf /usr/share/zoneinfo/Australia/Melbourne /etc/localtime
## ECR Repo
ECR_REPO="${!ACCOUNT_ID}.dkr.ecr.${!REGION}.amazonaws.com/"
...
In my stack declaration I then place the following dict:在我的堆栈声明中,我然后放置以下字典:
mappings = {"__ACCOUNT_ID__": self.account,
"__REGION__": self.region}
And read the user_data.sh
into the sub function, with the mappings dict as the second parameter并将user_data.sh
读入子函数,映射dict作为第二个参数
with open("user_data/user_data.sh", 'r') as user_data_h:
# Use a substitution
user_data_sub = core.Fn.sub(user_data_h.read(), mappings)
Then use the custom attribute from the UserData module.然后使用 UserData 模块中的自定义属性。
# Import substitution object into user_data set
user_data = ec2.UserData.custom(user_data_sub)
Pros:优点:
Cons:缺点:
core.Aws
object.令牌变量难以阅读,并且仅限于core.Aws
对象的属性。 Such as AccountID and Region.例如 AccountID 和 Region。You can run print statements inside the cdk workflow to assist you in determining what the variables such as core.Aws.ACCOUNT_ID
and core.Aws.REGION
are evaluated to and use these inside the user_data script.您可以在 cdk 工作流中运行打印语句,以帮助您确定诸如core.Aws.ACCOUNT_ID
和core.Aws.REGION
类的变量的评估结果,并在 user_data 脚本中使用这些变量。 (I'm writing my deployment in python and have based it from the ec2 on an existing VPC from the aws official examples repo . (我正在用 python 编写我的部署,并将它从 ec2 基于来自aws 官方示例 repo的现有 VPC。
ie: IE:
host = ec2.Instance(...)
print(core.aws.ACCOUNT_ID)
print(core.Aws.REGION)
I then run cdk synth
which yields:然后我运行cdk synth
产生:
${Token[AWS::AccountId.0]}
${Token[AWS::Region.4]}
Resources:...
From here I can use these in my user_data script: ie从这里我可以在我的 user_data 脚本中使用这些:即
#!/bin/bash
ACCOUNT_ID="${Token[AWS::AccountId.0]}"
REGION="${Token[AWS::Region.4]}"
## Updates
yum update -y
## Fix time
ln -sf /usr/share/zoneinfo/Australia/Melbourne /etc/localtime
Note now when re-running cdk synth
these are recognised as special by the yaml constructor (The yaml double spacing is a known cdk bug):现在请注意,当重新运行cdk synth
,yaml 构造函数会将它们识别为特殊的(yaml 双间距是已知的 cdk 错误):
...
UserData:
Fn::Base64:
Fn::Join:
- ""
- - >-
#!/bin/bash
# AWS vars:
ACCOUNT_ID="
- Ref: AWS::AccountId
- >-
"
REGION="
- Ref: AWS::Region
- >-
"
## Updates
yum update -y
## Fix time
ln -sf /usr/share/zoneinfo/Australia/Melbourne /etc/localtime
## ECR Repo
EC2_REPO="${ACCOUNT_ID}.dkr.ecr.${REGION}.amazonaws.com/"
...
I found the following to work with python我发现以下内容可以与 python 一起使用
from aws_cdk import (
aws_ec2,
core
)
host = aws_ec2.Instance(...)
host.add_user_data('', join([
'yum install -y aws-cfn-bootstrap\n',
f'/opt/aws/bin/cfn-init -v -s {core.Aws.STACK_NAME} -r {host.node.default_child.logical_id}\n'
])
meta_data = {
'config': {
'packages': {...},
'files': {...},
...
}
}
# for adding the meta data in a way that gets synth
host.node.default_child.add_overide('Metadata.AWS::CloudFormation::Init', meta_data)
This is using the CfnInstance
object you get from host.node.default_child
这是使用您从host.node.default_child
获得的CfnInstance
对象
You can access those pseudo-params by using the core module:您可以使用核心模块访问这些伪参数:
from aws_cdk import core
# other code...
EC2InstanceUserData = aws_ec2.UserData.for_windows()
EC2InstanceUserData.add_commands(
"cfn-signal.exe --exit-code 0 ",
f"--stack {core.Aws.STACK_ID}",
f" --resource {EC2Instance}", # Without more context, I'm not sure if this is exactly what you're wanting
f" --region {core.Aws.REGION}",
)
# other code ...
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