保留PyYaml转储

Question

我正在尝试编辑一个yaml文件，但当我编写新文件时，整个文件结构都乱七八糟。

换行符是错误的，一些缩进也是错误的，它甚至因为某些原因删除了我的一些参数。下面是一个例子：

在此之前

AWSTemplateFormatVersion: "2010-09-09"
Metadata:
    Generator: "user"
Description: "CloudFormation blah blah"

Parameters:
  VPCEndpointServiceServiceName:
    Description: VPCEndpointServiceServiceName
    Type: String

Mappings:
  PrivateLink:
    EndPoint:
      EndPointName: test
      EndPointVpcId: vpc-123
      SecurityGroupIds: sg-123
      SubnetId1: subnet-123
      SubnetId2: subnet-123

Resources:
    EC2VPCEndpoint:
        Type: "AWS::EC2::VPCEndpoint"
        Properties:
            VpcEndpointType: "Interface"
            VpcId: !FindInMap [PrivateLink, EndPoint, EndPointVpcId]
            ServiceName: !Ref VPCEndpointServiceServiceName
            SubnetIds:
              - !FindInMap [PrivateLink, EndPoint, SubnetId1]
              - !FindInMap [PrivateLink, EndPoint, SubnetId2]
            PrivateDnsEnabled: false
            SecurityGroupIds:
              - !FindInMap [PrivateLink, EndPoint, SecurityGroupIds]

之后

AWSTemplateFormatVersion: '2010-09-09'
Metadata:
  Generator: user
Description: CloudFormation blah blah
Parameters:
  VPCEndpointServiceServiceName:
    Description: VPCEndpointServiceServiceName
    Type: String
Mappings:
  PrivateLink:
    EndPoint:
      EndPointName: test
      EndPointVpcId: vpc-123
      SecurityGroupIds: sg-123
      SubnetId1: subnet-123
      SubnetId2: subnet-123
Resources:
  EC2VPCEndpoint:
    Type: AWS::EC2::VPCEndpoint
    Properties:
      VpcEndpointType: Interface
      VpcId:
      - PrivateLink
      - EndPoint
      - EndPointVpcId
      ServiceName: VPCEndpointServiceServiceName
      SubnetIds:
      - - PrivateLink
        - EndPoint
        - SubnetId1
      - - PrivateLink
        - EndPoint
        - SubnetId2
      PrivateDnsEnabled: 'false'
      SecurityGroupIds:
      - - PrivateLink
        - EndPoint
        - SecurityGroupIds

真正奇怪的是，它还删除了像!FindInMap和!Ref这样的参数。

下面是我的函数：

def editEndpointTemplate(endpoint_tempplate_path):
    #read yaml file
    with open(endpoint_tempplate_path) as file:
        data = yaml.load(file, Loader=yaml.BaseLoader)

    data['Mappings']['PrivateLink']['EndPoint']['EndPointName'] = "New Name"

    #write yaml file and overwrite old one.
    with open(endpoint_tempplate_path, 'w') as file:
        yaml.dump(data, file, sort_keys=False)

我想完全保留文件的原样，因为我所做的只是更新一些密钥。

我对按字母排序的文件也有问题，但一个简单的sort_keys=False解决了这个问题。我认为PyYaml的任何其他属性都可以解决这个问题，但我搞不清楚。

任何帮助都将不胜感激。

Answer 1

已找到解决方法。我没有使用PyYaml或cfn-tools，而是使用了ruamel.yaml。

import sys
from ruamel.yaml import YAML

def editEndpointTemplate(endpoint_template_path):
    yaml = YAML()
    yaml.indent(mapping=3)

    #Load yaml file
    with open(endpoint_template_path) as fp:
        data = yaml.load(fp)

    #Change data
    data['Mappings']['PrivateLink']['EndPoint']['EndPointName'] = service_name

    #Dump it back to the same file
    # yaml.dump(data, sys.stdout)
    with open(endpoint_template_path, 'w') as fp:
        yaml.dump(data, fp)

即使在编辑之后，新的YAML文件也会像我的模板一样被保留。