Convert byte slice to io.Reader
Solution 1:
To get a type that implements io.Reader from a []byte slice, you can use bytes.NewReader in the bytes package:
r := bytes.NewReader(byteData)
This will return a value of type bytes.Reader which implements the io.Reader (and io.ReadSeeker) interface.
Don't worry about them not being the same "type". io.Reader is an interface and can be implemented by many different types. To learn a little bit more about interfaces in Go, read Effective Go: Interfaces and Types.