How to Call Lambda Function Versions from a .NET Program

Answer - C.

The AWS Documentation mentions the following.

You can create one or more aliases for your Lambda function.

An AWS Lambda alias is like a pointer to a specific Lambda function version.

By using aliases, you can access the Lambda function.

An alias is pointing to (for example, to invoke the function) without the caller having to know the specific version the alias is pointing to.

Option A is invalid since environment variables in AWS Lambda are used to dynamically pass settings to your function code and libraries without making changes to the Lambda code.

Option B is invalid since this is used to publish one or more versions of your Lambda function.

Option D is invalid since this is used to define serverless applications.

For more information on ALIAS, please refer to the below URL-

https://docs.aws.amazon.com/lambda/latest/dg/aliases-intro.html

The easiest way to call different versions of a Lambda function with the least amount of changes to the .Net program would be to create one or more aliases for the Lambda function. The correct answer is C.

An alias is a pointer to a specific version of a Lambda function. By creating an alias, you can direct traffic to different versions of the function without having to change the function's ARN (Amazon Resource Name) in your code. This means that you can easily test different versions of the function without having to modify your .Net program every time.

Here's how you can create an alias for a Lambda function:

1. Open the AWS Lambda console.
2. Choose the function for which you want to create an alias.
3. In the Function overview section, choose the Aliases tab.
4. Choose Create Alias.
5. Enter a name for the alias and choose the version of the function that you want to point the alias to.
6. Choose Create.

You can create multiple aliases for a function and direct traffic to different versions of the function using each alias.

Once you have created the alias, you can reference it in your .Net program instead of the actual function ARN. This way, when you want to test a different version of the function, you just need to change the version that the alias points to, and your .Net program will automatically start calling the new version.

Creating different environment variables for the Lambda function (option A) wouldn't be the best solution in this case because it would require modifying the .Net program every time you want to test a different version of the function.

Creating different versions for the Lambda function (option B) would work, but it would still require modifying the .Net program to point to the new version every time you want to test a different version.

Using the SAM (Serverless Application Model) for deployment of the functions (option D) is a good practice, but it wouldn't help in this specific case of testing different versions of the function with the least amount of changes to the .Net program.