Python random size and element

I have to create an array in Python with random elements, random numbers of elements. The only important thing is that: the size should be equal to the sum of all elements.

Examples: range of elements min=1, max=1024, sum=1024.

1. case: [1000, 13, 11], 3 elements, their sum is 1024.
2. case: [500, 200, 100, 2, 22, 150, 50], 7 elements, their sum is 1024.

It doesn't matter if there are identical number [512, 512]. Can someone explain me how to do that?