在AWS CloudFormation中，可以使用cfn-init命令来执行一些自定义的初始化操作。有时候，使用cfn-init命令中的变量时可能会遇到未插值的问题。以下是解决该问题的一种方法：

在cfn-init命令中，可以使用--configsets参数来指定要执行的配置集。可以在配置集中定义要加载的配置文件和执行的命令。为了确保变量被正确插值，可以将要使用的变量定义在一个单独的配置文件中，然后将其加载到配置集中。

下面是一个示例：

1. 在CloudFormation模板中定义一个资源，该资源使用AWS::CloudFormation::Init来执行初始化操作。在此示例中，我们将创建一个EC2实例，并使用cfn-init命令执行初始化操作。

"Resources": {
  "MyEC2Instance": {
    "Type": "AWS::EC2::Instance",
    "Properties": {
      "ImageId": "ami-xxxxxxxx",
      "InstanceType": "t2.micro",
      "UserData": {
        "Fn::Base64": {
          "Fn::Join": [
            "",
            [
              "#!/bin/bash\n",
              "yum update -y aws-cfn-bootstrap\n",
              "# Install cfn-init\n",
              "/opt/aws/bin/cfn-init -v ",
              "         --stack ",
              {
                "Ref": "AWS::StackName"
              },
              "         --resource MyEC2Instance ",
              "         --configsets InstallAndRun ",
              "         --region ",
              {
                "Ref": "AWS::Region"
              },
              "\n"
            ]
          ]
        }
      }
    },
    "Metadata": {
      "AWS::CloudFormation::Init": {
        "configSets": {
          "InstallAndRun": [
            "InstallConfig",
            "RunConfig"
          ]
        },
        "InstallConfig": {
          "packages": {
            "yum": {
              "python3": []
            }
          },
          "files": {
            "/etc/cfn/cfn-hup.conf": {
              "content": {
                "Fn::Join": [
                  "",
                  [
                    "[main]\n",
                    "stack=",
                    {
                      "Ref": "AWS::StackId"
                    },
                    "\n",
                    "region=",
                    {
                      "Ref": "AWS::Region"
                    },
                    "\n",
                    "interval=5\n"
                  ]
                ]
              },
              "mode": "000400",
              "owner": "root",
              "group": "root"
            },
            "/etc/cfn/hooks.d/cfn-auto-reloader.conf": {
              "content": {
                "Fn::Join": [
                  "",
                  [
                    "[cfn-auto-reloader-hook]\n",
                    "triggers=post.update\n",
                    "path=Resources.MyEC2Instance.Metadata.AWS::CloudFormation::Init\n",
                    "action=/opt/aws/bin/cfn-init -v ",
                    "         --stack ",
                    {
                      "Ref": "AWS::StackName"
                    },
                    "         --resource MyEC2Instance ",
                    "         --configsets InstallAndRun ",
                    "         --region ",
                    {
                      "Ref": "AWS::Region"
                    },
                    "\n"
                  ]
                ]
              },
              "mode": "000400",
              "owner": "root",
              "group": "root"
            }
          },
          "commands": {
            "01_register_with_elb": {
              "command": {
                "Fn::Join": [
                  "",
                  [
                    "/usr/bin/python3 ",
                    "/opt/aws/bin/cfn-signal ",
                    "-e $? ",
                    "         --stack ",
                    {
                      "Ref": "AWS::StackName"
                    },
                    "         --resource MyEC2Instance ",
                    "         --region ",
                    {
                      "Ref": "AWS::Region"
                    },
                    "\n"
                  ]
                ]
              },
              "env": {
                "AWS_DEFAULT_REGION": {
                  "Ref": "AWS::Region"
                }
              }
            }
          }
        },
        "RunConfig": {
          "commands": {
            "01_run_script": {
              "command": "python3 /path/to/script.py"
            }
          }
        }
      }
    }
  }
}

在上面的示例中，我们使用了两个配置集：InstallConfig和RunConfig。在InstallConfig中，我们安装了python3，并定义了两个文件：cfn-hup.conf和cfn