Lambda: Function URL vs Alias Function URL

Question

Trying to get to grips with some CloudFormation scripts and my limited experience of Lambda, but what is the difference between a Function URL and an Alias Function URL?

From the documentation it appears to be that the Lambda Function URL will always use the *$LATEST* version of a function, while an Alias Function URL can be associated with a particular version which could differ from *$LATEST*. Given my understanding, is there any value in creating an Alias named *latest* which points to version *$LATEST*?

In addition, if creating, and assuming it is possible, Lambda and Alias Function URLs would these have the same values or would the URL ID differ, i.e. *https://.lambda-url..on.aws*?

Riku_Kobayashi · Answer

Hello.

If you create a function URL for each alias, the ID included in the URL will be different.  
For example, you can create an alias for each production environment or development environment, edit the "$LATEST" version, and then deploy to the development or production environment alias after testing.  
Therefore, I think the best way to use "$LATEST" is to use it for testing, and then deploy it to another alias once the testing is complete.  
https://dev.classmethod.jp/articles/expose-your-lambda-with-function-urls/#Developer%2520%252F%2520Solutions%2520Architect%2520POV  
https://docs.aws.amazon.com/lambda/latest/dg/configuration-aliases.html

Lambda: Function URL vs Alias Function URL

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