Consider the question. "Lullaby" is a song by American rock singer Shawn Mullins, from the album Soul's Core. It was released in 1998. The song has been Mullins' most successful song to date, reaching number-one on the Adult Top 40, number 7 on the Billboard Hot 100, and number 9 on the Modern Rock Tracks in the United States. It also had success abroad, reaching number 9 on the UK Singles Chart, number 5 in Australia and number 2 in Canada.

Who sings everything's going to be alright rockabye?
 If the answer is 'Shawn Mullins'; explain the reasoning:
To answer this question, we should know that: "Lullaby" is a song by American rock singer Shawn Mullins, from the album Soul's Core.