使用os.getenv在golang中声明常量。结果“在os.Getenv（“ MY_SECRET”）不是常量的常量初始化程序”中

Question

If I declare constants as the following I get the error 'const initializer in os.Getenv("MY_SECRET") is not a constant'. Why is this?

New to Go and I see the return type of Getenv is a string, but I don't understand why this wouldn't work as a constant.

const (
    secret     = os.Getenv("MY_SECRET")
    key        = os.Getenv("MY_KEY")
)

Answer 1

Just like the error says, a constant must have a constant value. You cannot set it to the return of a function. It must be evaluated at compile time (e.g. a string literal). If you want to store the values of environment variables looked up at run time, you'll have to store them in variables, not constants.