### [Read this on the main serverless docs site](https://www.serverless.com/framework/docs/providers/tencent/guide/variables/) # Tencent-SCF Variables Variables allow users to dynamically replace config values in `serverless.yml` config. They are especially useful when providing secrets for your service to use and when you are working with multiple stages. The Serverless framework provides a powerful variable system which allows you to add dynamic data into your `serverless.yml`. With Serverless Variables, you'll be able to do the following: - Reference & load variables from environment variables **Note:** You can only use variables in `serverless.yml` property **values**, not property keys. So you can't use variables to generate dynamic logical IDs in the custom resources section for example. ## Reference variables from environment variables To reference variables from environment variables, use the `${env:someProperty}` syntax in your `serverless.yml`. ```yml service: new-service provider: name: tencent runtime: Nodejs8.9 credentials: ~/.tencent/credentials environment: variables: ENV_FIRST: ${env:TENCENTCLOUD_APPID} ```